Add a C89 compliance test for the headers.

Technically we still require a couple things from C99 like "bool",
but it works with -std=c89 under gcc.

26 files changed, 396 insertions, 325 deletions

diff --git a/libdimension/Doxyfile.in b/libdimension/Doxyfile.in
index 0193155..d52fe97 100644
--- a/libdimension/Doxyfile.in
+++ b/libdimension/Doxyfile.in
@@ -40,4 +40,4 @@ HTML_FILE_EXTENSION    = .html
 GENERATE_LATEX         = YES
 LATEX_OUTPUT           = latex
 
-PREDEFINED             = "__STDC_VERSION__=199901L" "__GNUC__"
+PREDEFINED             = "__STDC_VERSION__=201112L" "__GNUC__"
diff --git a/libdimension/dimension.h b/libdimension/dimension.h
index 57458c1..19b43bc 100644
--- a/libdimension/dimension.h
+++ b/libdimension/dimension.h
@@ -40,26 +40,11 @@
 #define DIMENSION_H
 
 #ifdef __cplusplus
-// We've been included from a C++ file; mark everything here as extern "C"
+/* We've been included from a C++ file; mark everything here as extern "C" */
 extern "C" {
 #endif
 
-// Common macros
-
-/**
- * @internal
- * @def DMNSN_FUNC
- * @brief Expands to the name of the current function
- */
-#ifdef __GNUC__
-  #define DMNSN_FUNC __PRETTY_FUNCTION__
-#elif __STDC_VERSION__ >= 199901L
-  #define DMNSN_FUNC __func__
-#else
-  #define DMNSN_FUNC "<unknown function>"
-#endif
-
-// Common types
+/* Common types */
 
 /**
  * Generic callback type.
@@ -73,7 +58,7 @@ typedef void dmnsn_callback_fn(void *ptr);
  */
 typedef void dmnsn_free_fn(void *ptr);
 
-// Include all the libdimension headers
+/* Include all the libdimension headers */
 #include <dimension/compiler.h>
 #include <dimension/error.h>
 #include <dimension/malloc.h>
@@ -112,4 +97,4 @@ typedef void dmnsn_free_fn(void *ptr);
 }
 #endif
 
-#endif // DIMENSION_H
+#endif /* DIMENSION_H */
diff --git a/libdimension/dimension/array.h b/libdimension/dimension/array.h
index 9b38e29..9261a0e 100644
--- a/libdimension/dimension/array.h
+++ b/libdimension/dimension/array.h
@@ -23,16 +23,16 @@
  * Simple dynamic arrays.
  */
 
-#include <stddef.h> // For size_t
-#include <stdlib.h> // For qsort()
-#include <string.h> // For memcpy()
+#include <stddef.h> /* For size_t */
+#include <stdlib.h> /* For qsort() */
+#include <string.h> /* For memcpy() */
 
-/// Dynamic array type.
+/** Dynamic array type. */
 typedef struct dmnsn_array {
-  void *ptr;       ///< @internal The actual memory.
-  size_t obj_size; ///< @internal The size of each object.
-  size_t length;   ///< @internal The current size of the array.
-  size_t capacity; ///< @internal The size of the allocated space.
+  void *ptr;       /**< @internal The actual memory. */
+  size_t obj_size; /**< @internal The size of each object. */
+  size_t length;   /**< @internal The current size of the array. */
+  size_t capacity; /**< @internal The size of the allocated space. */
 } dmnsn_array;
 
 /**
@@ -46,9 +46,9 @@ dmnsn_init_array(dmnsn_array *array, size_t obj_size)
 {
   array->obj_size = obj_size;
   array->length   = 0;
-  array->capacity = 2; // Start with capacity of 2
+  array->capacity = 2; /* Start with capacity of 2 */
 
-  // Allocate the memory
+  /* Allocate the memory */
   array->ptr = dmnsn_malloc(array->capacity*array->obj_size);
 }
 
@@ -134,8 +134,8 @@ DMNSN_INLINE void
 dmnsn_array_resize(dmnsn_array *array, size_t length)
 {
   if (length > array->capacity) {
-    // Resize if we don't have enough capacity
-    array->capacity = length*2; // We are greedy
+    /* Resize if we don't have enough capacity */
+    array->capacity = length*2; /* We are greedy */
     array->ptr = dmnsn_realloc(array->ptr, array->obj_size*array->capacity);
   }
 
@@ -197,7 +197,7 @@ DMNSN_INLINE void
 dmnsn_array_set(dmnsn_array *array, size_t i, const void *obj)
 {
   if (i >= dmnsn_array_size(array)) {
-    // Resize if i is out of range
+    /* Resize if i is out of range */
     dmnsn_array_resize(array, i + 1);
   }
   memcpy((char *)array->ptr + array->obj_size*i, obj, array->obj_size);
@@ -259,8 +259,8 @@ dmnsn_array_pop(dmnsn_array *array, void *obj)
 {
   size_t size = dmnsn_array_size(array);
   dmnsn_assert(size > 0, "Array is empty.");
-  dmnsn_array_get(array, size - 1, obj); // Copy the object
-  dmnsn_array_resize(array, size - 1);   // Shrink the array
+  dmnsn_array_get(array, size - 1, obj); /* Copy the object */
+  dmnsn_array_resize(array, size - 1);   /* Shrink the array */
 }
 
 /**
@@ -277,11 +277,11 @@ dmnsn_array_insert(dmnsn_array *array, size_t i, const void *obj)
     size = i + 1;
   dmnsn_array_resize(array, size);
 
-  // Move the elements at and after `i' 1 to the right
+  /* Move the elements at and after `i' 1 to the right */
   memmove((char *)array->ptr + array->obj_size*(i + 1),
           (char *)array->ptr + array->obj_size*i,
           array->obj_size*(size - i - 1));
-  // Insert `obj' at `i'
+  /* Insert `obj' at `i' */
   memcpy((char *)array->ptr + array->obj_size*i, obj, array->obj_size);
 }
 
@@ -295,11 +295,11 @@ dmnsn_array_remove(dmnsn_array *array, size_t i)
 {
   size_t size = dmnsn_array_size(array);
   dmnsn_assert(i < size, "Array index out of bounds.");
-  // Move the array elements after `i' 1 to the left
+  /* Move the array elements after `i' 1 to the left */
   memmove((char *)array->ptr + array->obj_size*i,
           (char *)array->ptr + array->obj_size*(i + 1),
           array->obj_size*(size - i - 1));
-  // Decrease the size by 1
+  /* Decrease the size by 1 */
   dmnsn_array_resize(array, size - 1);
 }
 
@@ -337,7 +337,7 @@ dmnsn_array_sort(dmnsn_array *array, dmnsn_array_comparator_fn *comparator)
   qsort(array->ptr, dmnsn_array_size(array), array->obj_size, comparator);
 }
 
-// Macros to shorten array iteration
+/* Macros to shorten array iteration */
 
 /**
  * Iterate over an array.  For example,
diff --git a/libdimension/dimension/camera.h b/libdimension/dimension/camera.h
index 30a01cc..3c6494c 100644
--- a/libdimension/dimension/camera.h
+++ b/libdimension/dimension/camera.h
@@ -23,7 +23,7 @@
  * Cameras.
  */
 
-// Forward-declare dmnsn_camera
+/* Forward-declare dmnsn_camera */
 typedef struct dmnsn_camera dmnsn_camera;
 
 /**
@@ -36,12 +36,12 @@ typedef struct dmnsn_camera dmnsn_camera;
 typedef dmnsn_line dmnsn_camera_ray_fn(const dmnsn_camera *camera,
                                        double x, double y);
 
-/// A camera.
+/** A camera. */
 struct dmnsn_camera {
-  // Callback functions
-  dmnsn_camera_ray_fn *ray_fn; ///< Camera ray callback.
+  /* Callback functions */
+  dmnsn_camera_ray_fn *ray_fn; /**< Camera ray callback. */
 
-  dmnsn_matrix trans; ///< Transformation matrix.
+  dmnsn_matrix trans; /**< Transformation matrix. */
 };
 
 /**
diff --git a/libdimension/dimension/canvas.h b/libdimension/dimension/canvas.h
index 765260d..d03a37e 100644
--- a/libdimension/dimension/canvas.h
+++ b/libdimension/dimension/canvas.h
@@ -25,12 +25,12 @@
 
 #include <stddef.h>
 
-/// A canvas, or image.
+/** A canvas, or image. */
 typedef struct dmnsn_canvas {
-  size_t width;  ///< Canvas width.
-  size_t height; ///< Canvas height.
+  size_t width;  /**< Canvas width. */
+  size_t height; /**< Canvas height. */
 
-  /// An array of <tt>dmnsn_canvas_optimizer</tt>s.
+  /** An array of <tt>dmnsn_canvas_optimizer</tt>s. */
   dmnsn_array *optimizers;
 
   /**
@@ -51,12 +51,12 @@ typedef struct dmnsn_canvas {
 typedef void dmnsn_canvas_optimizer_fn(const dmnsn_canvas *canvas, void *ptr,
                                        size_t x, size_t y);
 
-/// Canvas optimizer.
+/** Canvas optimizer. */
 typedef struct dmnsn_canvas_optimizer {
-  dmnsn_canvas_optimizer_fn *optimizer_fn; ///< Optimizer callback.
-  dmnsn_free_fn             *free_fn;      ///< Destructor callback.
+  dmnsn_canvas_optimizer_fn *optimizer_fn; /**< Optimizer callback. */
+  dmnsn_free_fn             *free_fn;      /**< Destructor callback. */
 
-  void *ptr; ///< Generic pointer.
+  void *ptr; /**< Generic pointer. */
 } dmnsn_canvas_optimizer;
 
 /**
@@ -87,7 +87,7 @@ dmnsn_canvas_optimizer *
 dmnsn_canvas_find_optimizer(const dmnsn_canvas *canvas,
                             dmnsn_canvas_optimizer_fn *optimizer_fn);
 
-// Pixel accessors
+/* Pixel accessors */
 
 /**
  * Get the color of a pixel.
diff --git a/libdimension/dimension/color.h b/libdimension/dimension/color.h
index 3eacbfe..afc4a5c 100644
--- a/libdimension/dimension/color.h
+++ b/libdimension/dimension/color.h
@@ -25,19 +25,19 @@
 
 #include <stdbool.h>
 
-/// A color value.
+/** A color value. */
 typedef struct {
-  double R; ///< Red component.
-  double G; ///< Green component.
-  double B; ///< Blue component.
+  double R; /**< Red component. */
+  double G; /**< Green component. */
+  double B; /**< Blue component. */
 } dmnsn_color;
 
-/// A standard format string for colors.
+/** A standard format string for colors. */
 #define DMNSN_COLOR_FORMAT "Color<%g, %g, %g>"
-/// The appropriate arguements to printf() a color.
+/** The appropriate arguements to printf() a color. */
 #define DMNSN_COLOR_PRINTF(c) (c).R, (c).G, (c).B
 
-/// Construct a new color.
+/** Construct a new color. */
 DMNSN_INLINE dmnsn_color
 dmnsn_new_color(double R, double G, double B)
 {
@@ -45,17 +45,19 @@ dmnsn_new_color(double R, double G, double B)
   return ret;
 }
 
-/// Apply sRGB gamma
+/** Apply sRGB gamma */
 DMNSN_INLINE double
 dmnsn_sRGB_gamma(double Clinear)
 {
-  // If C represents R, G, and B, then the sRGB values are now found as follows:
-  //
-  //         { 12.92*Clinear,                Clinear <= 0.0031308
-  // Csrgb = {                1/2.4
-  //         { (1.055)*Clinear      - 0.055, Clinear >  0.0031308
+  /*
+   * If C represents R, G, and B, then the sRGB values are now found as follows:
+   *
+   *         { 12.92*Clinear,                Clinear <= 0.0031308
+   * Csrgb = {                1/2.4
+   *         { (1.055)*Clinear      - 0.055, Clinear >  0.0031308
+   */
   if (Clinear == 1.0) {
-    return 1.0; // Map 1.0 to 1.0 instead of 0.9999999999999999
+    return 1.0; /* Map 1.0 to 1.0 instead of 0.9999999999999999 */
   } else if (Clinear > 0.0031308) {
     return 1.055*pow(Clinear, 1.0/2.4) - 0.055;
   } else {
@@ -63,7 +65,7 @@ dmnsn_sRGB_gamma(double Clinear)
   }
 }
 
-/// Convert to sRGB space.
+/** Convert to sRGB space. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_to_sRGB(dmnsn_color color)
 {
@@ -74,18 +76,20 @@ dmnsn_color_to_sRGB(dmnsn_color color)
   );
 }
 
-/// Remove sRGB gamma
+/** Remove sRGB gamma */
 DMNSN_INLINE double
 dmnsn_sRGB_inverse_gamma(double CsRGB)
 {
-  // If C represents R, G, and B, then the Clinear values are now found as
-  // follows:
-  //
-  //           { Csrgb/12.92,                Csrgb <= 0.04045
-  // Clinear = {                        2.4
-  //           { ((Csrgb + 0.055)/1.055)   , Csrgb >  0.04045
+  /*
+   * If C represents R, G, and B, then the Clinear values are now found as
+   * follows:
+   *
+   *           { Csrgb/12.92,                Csrgb <= 0.04045
+   * Clinear = {                        2.4
+   *           { ((Csrgb + 0.055)/1.055)   , Csrgb >  0.04045
+   */
   if (CsRGB == 1.0) {
-    return 1.0; // Map 1.0 to 1.0 instead of 0.9999999999999999
+    return 1.0; /* Map 1.0 to 1.0 instead of 0.9999999999999999 */
   } else if (CsRGB <= 0.040449936) {
     return CsRGB/12.92;
   } else {
@@ -93,7 +97,7 @@ dmnsn_sRGB_inverse_gamma(double CsRGB)
   }
 }
 
-/// Convert from sRGB space.
+/** Convert from sRGB space. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_from_sRGB(dmnsn_color color)
 {
@@ -104,35 +108,35 @@ dmnsn_color_from_sRGB(dmnsn_color color)
   );
 }
 
-/// Greyscale color intensity.
+/** Greyscale color intensity. */
 DMNSN_INLINE double
 dmnsn_color_intensity(dmnsn_color color)
 {
   return 0.2126*color.R + 0.7152*color.G + 0.0722*color.B;
 }
 
-/// Add two colors together.
+/** Add two colors together. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_add(dmnsn_color lhs, dmnsn_color rhs)
 {
   return dmnsn_new_color(lhs.R + rhs.R, lhs.G + rhs.G, lhs.B + rhs.B);
 }
 
-/// Subtract two colors.
+/** Subtract two colors. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_sub(dmnsn_color lhs, dmnsn_color rhs)
 {
   return dmnsn_new_color(lhs.R - rhs.R, lhs.G - rhs.G, lhs.B - rhs.B);
 }
 
-/// Scale a color's intensity.
+/** Scale a color's intensity. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_mul(double n, dmnsn_color color)
 {
   return dmnsn_new_color(n*color.R, n*color.G, n*color.B);
 }
 
-/// Return the color at \p n on a gradient from \p c1 at 0 to \p c2 at 1.
+/** Return the color at \p n on a gradient from \p c1 at 0 to \p c2 at 1. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n)
 {
@@ -143,14 +147,14 @@ dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n)
   );
 }
 
-/// Illuminate \p color with \p light.
+/** Illuminate \p color with \p light. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_illuminate(dmnsn_color light, dmnsn_color color)
 {
   return dmnsn_new_color(light.R*color.R, light.G*color.G, light.B*color.B);
 }
 
-/// Saturate the color components to [0.0, 1.0].
+/** Saturate the color components to [0.0, 1.0]. */
 DMNSN_INLINE dmnsn_color
 dmnsn_color_saturate(dmnsn_color color)
 {
@@ -160,30 +164,30 @@ dmnsn_color_saturate(dmnsn_color color)
   return color;
 }
 
-/// Return whether a color contains any NaN components.
+/** Return whether a color contains any NaN components. */
 DMNSN_INLINE bool
 dmnsn_color_isnan(dmnsn_color color)
 {
-  return isnan(color.R) || isnan(color.G) || isnan(color.B);
+  return dmnsn_isnan(color.R) || dmnsn_isnan(color.G) || dmnsn_isnan(color.B);
 }
 
-// Standard colors
+/* Standard colors */
 
-/// Black.
+/** Black. */
 #define dmnsn_black   dmnsn_new_color(0.0, 0.0, 0.0)
-/// White.
+/** White. */
 #define dmnsn_white   dmnsn_new_color(1.0, 1.0, 1.0)
-/// Red.
+/** Red. */
 #define dmnsn_red     dmnsn_new_color(1.0, 0.0, 0.0)
-/// Green.
+/** Green. */
 #define dmnsn_green   dmnsn_new_color(0.0, 1.0, 0.0)
-/// Blue.
+/** Blue. */
 #define dmnsn_blue    dmnsn_new_color(0.0, 0.0, 1.0)
-/// Magenta.
+/** Magenta. */
 #define dmnsn_magenta dmnsn_new_color(1.0, 0.0, 1.0)
-/// Orange.
+/** Orange. */
 #define dmnsn_orange  dmnsn_new_color(1.0, 0.21404114048223255, 0.0)
-/// Yellow.
+/** Yellow. */
 #define dmnsn_yellow  dmnsn_new_color(1.0, 1.0, 0.0)
-/// Cyan.
+/** Cyan. */
 #define dmnsn_cyan    dmnsn_new_color(0.0, 1.0, 1.0)
diff --git a/libdimension/dimension/compiler.h b/libdimension/dimension/compiler.h
index 952200b..3d392b5 100644
--- a/libdimension/dimension/compiler.h
+++ b/libdimension/dimension/compiler.h
@@ -30,23 +30,46 @@
  */
 #ifndef DMNSN_INLINE
   #ifdef __cplusplus
-    // C++ inline semantics
+    /* C++ inline semantics */
     #define DMNSN_INLINE inline
   #elif __STDC_VERSION__ >= 199901L
-    // C99 inline semantics
+    /* C99 inline semantics */
     #define DMNSN_INLINE inline
   #elif defined(__GNUC__)
-    // GCC inline semantics
+    /* GCC inline semantics */
     #define DMNSN_INLINE __extension__ extern __inline__
   #else
-    // Unknown C - mark functions static and hope the compiler is smart enough
-    // to inline them
+    /* Unknown C - mark functions static and hope the compiler is smart enough
+       to inline them */
     #define DMNSN_INLINE static
   #endif
 #endif
 
+/**
+ * @internal
+ * @def DMNSN_FUNC
+ * @brief Expands to the name of the current function
+ */
+#ifdef __GNUC__
+  #define DMNSN_FUNC __PRETTY_FUNCTION__
+#elif __STDC_VERSION__ >= 199901L
+  #define DMNSN_FUNC __func__
+#else
+  #define DMNSN_FUNC "<unknown function>"
+#endif
+
+/**
+ * @internal
+ * An unreachable statement.
+ */
 #ifdef __GNUC__
   #define DMNSN_UNREACHABLE() __builtin_unreachable()
 #else
   #define DMNSN_UNREACHABLE() ((void)0)
 #endif
+
+/**
+ * @internal
+ * Whether C99 features are supported.
+ */
+#define DMNSN_C99 (__STDC_VERSION__ >= 199901L || __cplusplus >= 201103L)
diff --git a/libdimension/dimension/dictionary.h b/libdimension/dimension/dictionary.h
index 15661de..887b171 100644
--- a/libdimension/dimension/dictionary.h
+++ b/libdimension/dimension/dictionary.h
@@ -23,7 +23,7 @@
  * Simple associative arrays.
  */
 
-/// A string-object associative array.
+/** A string-object associative array. */
 typedef struct dmnsn_dictionary dmnsn_dictionary;
 
 /**
diff --git a/libdimension/dimension/finish.h b/libdimension/dimension/finish.h
index 5471897..d975877 100644
--- a/libdimension/dimension/finish.h
+++ b/libdimension/dimension/finish.h
@@ -23,17 +23,17 @@
  * Object finishes.
  */
 
-// Ambient component
+/* Ambient component */
 
-/// Ambient finish component.
+/** Ambient finish component. */
 typedef struct dmnsn_ambient {
-  dmnsn_color ambient; ///< Ambient light.
+  dmnsn_color ambient; /**< Ambient light. */
 } dmnsn_ambient;
 
-/// Allocate an ambient component.
+/** Allocate an ambient component. */
 dmnsn_ambient *dmnsn_new_ambient(dmnsn_pool *pool, dmnsn_color ambient);
 
-// Diffuse component
+/* Diffuse component */
 
 typedef struct dmnsn_diffuse dmnsn_diffuse;
 
@@ -50,17 +50,17 @@ typedef dmnsn_color dmnsn_diffuse_fn(const dmnsn_diffuse *diffuse,
                                      dmnsn_color light, dmnsn_color color,
                                      dmnsn_vector ray, dmnsn_vector normal);
 
-/// Diffuse finish component.
+/** Diffuse finish component. */
 struct dmnsn_diffuse {
-  dmnsn_diffuse_fn *diffuse_fn; ///< Diffuse callback.
+  dmnsn_diffuse_fn *diffuse_fn; /**< Diffuse callback. */
 };
 
-/// Allocate a dummy diffuse component.
+/** Allocate a dummy diffuse component. */
 dmnsn_diffuse *dmnsn_new_diffuse(dmnsn_pool *pool);
-/// Initialize a dmnsn_diffuse field.
+/** Initialize a dmnsn_diffuse field. */
 void dmnsn_init_diffuse(dmnsn_diffuse *diffuse);
 
-// Specular component
+/* Specular component */
 
 typedef struct dmnsn_specular dmnsn_specular;
 
@@ -79,17 +79,17 @@ typedef dmnsn_color dmnsn_specular_fn(const dmnsn_specular *specular,
                                       dmnsn_vector ray, dmnsn_vector normal,
                                       dmnsn_vector viewer);
 
-/// Specular finish component.
+/** Specular finish component. */
 struct dmnsn_specular {
-  dmnsn_specular_fn *specular_fn; ///< Specular callback.
+  dmnsn_specular_fn *specular_fn; /**< Specular callback. */
 };
 
-/// Allocate a dummy specular component.
+/** Allocate a dummy specular component. */
 dmnsn_specular *dmnsn_new_specular(dmnsn_pool *pool);
-/// Initialize a dmnsn_specular field.
+/** Initialize a dmnsn_specular field. */
 void dmnsn_init_specular(dmnsn_specular *specular);
 
-// Reflection component
+/* Reflection component */
 
 typedef struct dmnsn_reflection dmnsn_reflection;
 
@@ -106,24 +106,24 @@ typedef dmnsn_color dmnsn_reflection_fn(const dmnsn_reflection *reflection,
                                         dmnsn_color reflect, dmnsn_color color,
                                         dmnsn_vector ray, dmnsn_vector normal);
 
-/// The reflection component.
+/** The reflection component. */
 struct dmnsn_reflection {
-  dmnsn_reflection_fn *reflection_fn; ///< Reflection callback.
+  dmnsn_reflection_fn *reflection_fn; /**< Reflection callback. */
 };
 
-/// Allocate a dummy reflection component.
+/** Allocate a dummy reflection component. */
 dmnsn_reflection *dmnsn_new_reflection(dmnsn_pool *pool);
-/// Initialize a dmnsn_reflection field.
+/** Initialize a dmnsn_reflection field. */
 void dmnsn_init_reflection(dmnsn_reflection *reflection);
 
-// Entire finishes
+/* Entire finishes */
 
-/// A finish.
+/** A finish. */
 typedef struct dmnsn_finish {
-  dmnsn_ambient *ambient; ///< Ambient component.
-  dmnsn_diffuse *diffuse; ///< Diffuse component.
-  dmnsn_specular *specular; ///< Specular component.
-  dmnsn_reflection *reflection; ///< Reflection component.
+  dmnsn_ambient *ambient; /**< Ambient component. */
+  dmnsn_diffuse *diffuse; /**< Diffuse component. */
+  dmnsn_specular *specular; /**< Specular component. */
+  dmnsn_reflection *reflection; /**< Reflection component. */
 } dmnsn_finish;
 
 /**
diff --git a/libdimension/dimension/future.h b/libdimension/dimension/future.h
index 263c647..9ba28b1 100644
--- a/libdimension/dimension/future.h
+++ b/libdimension/dimension/future.h
@@ -26,7 +26,7 @@
  * is returned as an int from dmnsn_finish_progress().
  */
 
-/// A future object.
+/** A future object. */
 typedef struct dmnsn_future dmnsn_future;
 
 /**
diff --git a/libdimension/dimension/geometry.h b/libdimension/dimension/geometry.h
index fd4a781..7b52a98 100644
--- a/libdimension/dimension/geometry.h
+++ b/libdimension/dimension/geometry.h
@@ -26,105 +26,115 @@
 #include <math.h>
 #include <stdbool.h>
 
-/// A vector in 3 dimensions.
+/** A vector in 3 dimensions. */
 typedef struct dmnsn_vector {
-  double x; ///< The x component.
-  double y; ///< The y component.
-  double z; ///< The z component.
+  double x; /**< The x component. */
+  double y; /**< The y component. */
+  double z; /**< The z component. */
 } dmnsn_vector;
 
-/// A standard format string for vectors.
+/** A standard format string for vectors. */
 #define DMNSN_VECTOR_FORMAT "<%g, %g, %g>"
-/// The appropriate arguements to printf() a vector.
+/** The appropriate arguements to printf() a vector. */
 #define DMNSN_VECTOR_PRINTF(v) (v).x, (v).y, (v).z
 
-/// A 4x4 affine transformation matrix, with implied [0 0 0 1] bottom row.
+/** A 4x4 affine transformation matrix, with implied [0 0 0 1] bottom row. */
 typedef struct dmnsn_matrix {
-  double n[3][4]; ///< The matrix elements in row-major order.
+  double n[3][4]; /**< The matrix elements in row-major order. */
 } dmnsn_matrix;
 
-/// A standard format string for matricies.
+/** A standard format string for matricies. */
 #define DMNSN_MATRIX_FORMAT                     \
   "[%g\t%g\t%g\t%g]\n"                          \
   "[%g\t%g\t%g\t%g]\n"                          \
   "[%g\t%g\t%g\t%g]\n"                          \
   "[%g\t%g\t%g\t%g]"
-/// The appropriate arguements to printf() a matrix.
+/** The appropriate arguements to printf() a matrix. */
 #define DMNSN_MATRIX_PRINTF(m)                          \
   (m).n[0][0], (m).n[0][1], (m).n[0][2], (m).n[0][3],   \
   (m).n[1][0], (m).n[1][1], (m).n[1][2], (m).n[1][3],   \
   (m).n[2][0], (m).n[2][1], (m).n[2][2], (m).n[2][3],   \
   0.0, 0.0, 0.0, 1.0
 
-/// A line, or ray.
+/** A line, or ray. */
 typedef struct dmnsn_line {
-  dmnsn_vector x0; ///< A point on the line.
-  dmnsn_vector n;  ///< A normal vector; the direction of the line.
+  dmnsn_vector x0; /**< A point on the line. */
+  dmnsn_vector n;  /**< A normal vector; the direction of the line. */
 } dmnsn_line;
 
-/// A standard format string for lines.
+/** A standard format string for lines. */
 #define DMNSN_LINE_FORMAT "(<%g, %g, %g> + t*<%g, %g, %g>)"
-/// The appropriate arguements to printf() a line.
+/** The appropriate arguements to printf() a line. */
 #define DMNSN_LINE_PRINTF(l)                                    \
   DMNSN_VECTOR_PRINTF((l).x0), DMNSN_VECTOR_PRINTF((l).n)
 
-/// An axis-aligned bounding box (AABB).
+/** An axis-aligned bounding box (AABB). */
 typedef struct dmnsn_bounding_box {
-  dmnsn_vector min; ///< The coordinate-wise minimum extent of the box.
-  dmnsn_vector max; ///< The coordinate-wise maximum extent of the box.
+  dmnsn_vector min; /**< The coordinate-wise minimum extent of the box. */
+  dmnsn_vector max; /**< The coordinate-wise maximum extent of the box. */
 } dmnsn_bounding_box;
 
-/// A standard format string for bounding boxes.
+/** A standard format string for bounding boxes. */
 #define DMNSN_BOUNDING_BOX_FORMAT "(<%g, %g, %g> ==> <%g, %g, %g>)"
-/// The appropriate arguements to printf() a bounding box.
+/** The appropriate arguements to printf() a bounding box. */
 #define DMNSN_BOUNDING_BOX_PRINTF(box)                                  \
   DMNSN_VECTOR_PRINTF((box).min), DMNSN_VECTOR_PRINTF((box).max)
 
-// Constants
+/* Constants */
 
-/// The smallest value considered non-zero by some numerical algorithms.
+/** The smallest value considered non-zero by some numerical algorithms. */
 #define dmnsn_epsilon 1.0e-10
 
-/// The zero vector.
+/** The zero vector. */
 static const dmnsn_vector dmnsn_zero = { 0.0, 0.0, 0.0 };
-/// The x vector.
+/** The x vector. */
 static const dmnsn_vector dmnsn_x = { 1.0, 0.0, 0.0 };
-/// The y vector.
+/** The y vector. */
 static const dmnsn_vector dmnsn_y = { 0.0, 1.0, 0.0 };
-/// The z vector.
+/** The z vector. */
 static const dmnsn_vector dmnsn_z = { 0.0, 0.0, 1.0 };
 
-// Scalar functions
+/**
+ * @def DMNSN_INFINITY
+ * Expands to floating-point infinity.
+ */
+#if defined(INFINITY) || DMNSN_C99
+  #define DMNSN_INFINITY INFINITY
+#else
+  #define DMNSN_INFINITY HUGE_VAL
+#endif
 
-/// Find the minimum of two scalars.
+/* Scalar functions */
+
+/** Find the minimum of two scalars. */
 DMNSN_INLINE double
 dmnsn_min(double a, double b)
 {
   return a < b ? a : b;
 }
 
-/// Find the maximum of two scalars.
+/** Find the maximum of two scalars. */
 DMNSN_INLINE double
 dmnsn_max(double a, double b)
 {
   return a > b ? a : b;
 }
 
-/// Convert degrees to radians.
+/** Convert degrees to radians. */
 DMNSN_INLINE double
 dmnsn_radians(double degrees)
 {
   return degrees*atan(1.0)/45.0;
 }
 
-/// Convert radians to degrees.
+/** Convert radians to degrees. */
 DMNSN_INLINE double
 dmnsn_degrees(double radians)
 {
   return radians*45.0/atan(1.0);
 }
 
-/// Return the sign of a scalar.
+/** Return the sign of a scalar. */
 DMNSN_INLINE int
 dmnsn_sign(double n)
 {
@@ -137,9 +147,9 @@ dmnsn_sign(double n)
   }
 }
 
-// Shorthand for vector/matrix construction
+/* Shorthand for vector/matrix construction */
 
-/// Construct a new vector.
+/** Construct a new vector. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_new_vector(double x, double y, double z)
 {
@@ -147,7 +157,7 @@ dmnsn_new_vector(double x, double y, double z)
   return v;
 }
 
-/// Construct a new transformation matrix.
+/** Construct a new transformation matrix. */
 DMNSN_INLINE dmnsn_matrix
 dmnsn_new_matrix(double a0, double a1, double a2, double a3,
                  double b0, double b1, double b2, double b3,
@@ -159,7 +169,7 @@ dmnsn_new_matrix(double a0, double a1, double a2, double a3,
   return m;
 }
 
-/// Construct a new transformation matrix from column vectors.
+/** Construct a new transformation matrix from column vectors. */
 DMNSN_INLINE dmnsn_matrix
 dmnsn_new_matrix4(dmnsn_vector a, dmnsn_vector b, dmnsn_vector c,
                   dmnsn_vector d)
@@ -170,14 +180,14 @@ dmnsn_new_matrix4(dmnsn_vector a, dmnsn_vector b, dmnsn_vector c,
   return m;
 }
 
-/// Extract column vectors from a matrix.
+/** Extract column vectors from a matrix. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_matrix_column(dmnsn_matrix M, unsigned int i)
 {
   return dmnsn_new_vector(M.n[0][i], M.n[1][i], M.n[2][i]);
 }
 
-/// Return the identity matrix.
+/** Return the identity matrix. */
 dmnsn_matrix dmnsn_identity_matrix(void);
 
 /**
@@ -238,119 +248,119 @@ dmnsn_new_bounding_box(dmnsn_vector min, dmnsn_vector max)
   return box;
 }
 
-/// Return the bounding box which contains nothing.
+/** Return the bounding box which contains nothing. */
 DMNSN_INLINE dmnsn_bounding_box
 dmnsn_zero_bounding_box(void)
 {
   dmnsn_bounding_box box = {
-    {  INFINITY,  INFINITY,  INFINITY },
-    { -INFINITY, -INFINITY, -INFINITY }
+    {  DMNSN_INFINITY,  DMNSN_INFINITY,  DMNSN_INFINITY },
+    { -DMNSN_INFINITY, -DMNSN_INFINITY, -DMNSN_INFINITY }
   };
   return box;
 }
 
-/// Return the bounding box which contains everything.
+/** Return the bounding box which contains everything. */
 DMNSN_INLINE dmnsn_bounding_box
 dmnsn_infinite_bounding_box(void)
 {
   dmnsn_bounding_box box = {
-    { -INFINITY, -INFINITY, -INFINITY },
-    {  INFINITY,  INFINITY,  INFINITY }
+    { -DMNSN_INFINITY, -DMNSN_INFINITY, -DMNSN_INFINITY },
+    {  DMNSN_INFINITY,  DMNSN_INFINITY,  DMNSN_INFINITY }
   };
   return box;
 }
 
-// Vector and matrix arithmetic
+/* Vector and matrix arithmetic */
 
-/// Negate a vector.
+/** Negate a vector. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_negate(dmnsn_vector rhs)
 {
-  // 3 negations
+  /* 3 negations */
   dmnsn_vector v = { -rhs.x, -rhs.y, -rhs.z };
   return v;
 }
 
-/// Add two vectors.
+/** Add two vectors. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_add(dmnsn_vector lhs, dmnsn_vector rhs)
 {
-  // 3 additions
+  /* 3 additions */
   dmnsn_vector v = { lhs.x + rhs.x, lhs.y + rhs.y, lhs.z + rhs.z };
   return v;
 }
 
-/// Subtract two vectors.
+/** Subtract two vectors. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_sub(dmnsn_vector lhs, dmnsn_vector rhs)
 {
-  // 3 additions
+  /* 3 additions */
   dmnsn_vector v = { lhs.x - rhs.x, lhs.y - rhs.y, lhs.z - rhs.z };
   return v;
 }
 
-/// Multiply a vector by a scalar.
+/** Multiply a vector by a scalar. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_mul(double lhs, dmnsn_vector rhs)
 {
-  // 3 multiplications
+  /* 3 multiplications */
   dmnsn_vector v = { lhs*rhs.x, lhs*rhs.y, lhs*rhs.z };
   return v;
 }
 
-/// Divide a vector by a scalar.
+/** Divide a vector by a scalar. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_div(dmnsn_vector lhs, double rhs)
 {
-  // 3 divisions
+  /* 3 divisions */
   dmnsn_vector v = { lhs.x/rhs, lhs.y/rhs, lhs.z/rhs };
   return v;
 }
 
-/// Return the dot product of two vectors.
+/** Return the dot product of two vectors. */
 DMNSN_INLINE double
 dmnsn_vector_dot(dmnsn_vector lhs, dmnsn_vector rhs)
 {
-  // 3 multiplications, 2 additions
+  /* 3 multiplications, 2 additions */
   return lhs.x*rhs.x + lhs.y*rhs.y + lhs.z*rhs.z;
 }
 
-/// Return the cross product of two vectors.
+/** Return the cross product of two vectors. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_cross(dmnsn_vector lhs, dmnsn_vector rhs)
 {
-  // 6 multiplications, 3 additions
+  /* 6 multiplications, 3 additions */
   dmnsn_vector v = { lhs.y*rhs.z - lhs.z*rhs.y,
                      lhs.z*rhs.x - lhs.x*rhs.z,
                      lhs.x*rhs.y - lhs.y*rhs.x };
   return v;
 }
 
-/// Return the projection of \p u onto \p d.
+/** Return the projection of \p u onto \p d. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_proj(dmnsn_vector u, dmnsn_vector d)
 {
-  // 1 division, 9 multiplications, 4 additions
+  /* 1 division, 9 multiplications, 4 additions */
   return dmnsn_vector_mul(dmnsn_vector_dot(u, d)/dmnsn_vector_dot(d, d), d);
 }
 
-/// Return the magnitude of a vector.
+/** Return the magnitude of a vector. */
 DMNSN_INLINE double
 dmnsn_vector_norm(dmnsn_vector n)
 {
-  // 1 sqrt, 3 multiplications, 2 additions
+  /* 1 sqrt, 3 multiplications, 2 additions */
   return sqrt(dmnsn_vector_dot(n, n));
 }
 
-/// Return the direction of a vector.
+/** Return the direction of a vector. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_normalized(dmnsn_vector n)
 {
-  // 1 sqrt, 3 divisions, 3 multiplications, 2 additions
+  /* 1 sqrt, 3 divisions, 3 multiplications, 2 additions */
   return dmnsn_vector_div(n, dmnsn_vector_norm(n));
 }
 
-/// Return the component-wise minimum of two vectors.
+/** Return the component-wise minimum of two vectors. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_min(dmnsn_vector a, dmnsn_vector b)
 {
@@ -361,7 +371,7 @@ dmnsn_vector_min(dmnsn_vector a, dmnsn_vector b)
   );
 }
 
-/// Return the component-wise maximum of two vectors.
+/** Return the component-wise maximum of two vectors. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_vector_max(dmnsn_vector a, dmnsn_vector b)
 {
@@ -372,17 +382,17 @@ dmnsn_vector_max(dmnsn_vector a, dmnsn_vector b)
   );
 }
 
-/// Invert a matrix.
+/** Invert a matrix. */
 dmnsn_matrix dmnsn_matrix_inverse(dmnsn_matrix A);
 
-/// Multiply two matricies.
+/** Multiply two matricies. */
 dmnsn_matrix dmnsn_matrix_mul(dmnsn_matrix lhs, dmnsn_matrix rhs);
 
-/// Transform a point by a matrix.
+/** Transform a point by a matrix. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_transform_point(dmnsn_matrix T, dmnsn_vector v)
 {
-  // 9 multiplications, 9 additions
+  /* 9 multiplications, 9 additions */
   dmnsn_vector r;
   r.x = T.n[0][0]*v.x + T.n[0][1]*v.y + T.n[0][2]*v.z + T.n[0][3];
   r.y = T.n[1][0]*v.x + T.n[1][1]*v.y + T.n[1][2]*v.z + T.n[1][3];
@@ -390,11 +400,11 @@ dmnsn_transform_point(dmnsn_matrix T, dmnsn_vector v)
   return r;
 }
 
-/// Transform a direction by a matrix.
+/** Transform a direction by a matrix. */
 DMNSN_INLINE dmnsn_vector
 dmnsn_transform_direction(dmnsn_matrix T, dmnsn_vector v)
 {
-  // 9 multiplications, 6 additions
+  /* 9 multiplications, 6 additions */
   dmnsn_vector r;
   r.x = T.n[0][0]*v.x + T.n[0][1]*v.y + T.n[0][2]*v.z;
   r.y = T.n[1][0]*v.x + T.n[1][1]*v.y + T.n[1][2]*v.z;
@@ -411,7 +421,8 @@ dmnsn_transform_direction(dmnsn_matrix T, dmnsn_vector v)
 DMNSN_INLINE dmnsn_vector
 dmnsn_transform_normal(dmnsn_matrix Tinv, dmnsn_vector v)
 {
-  // Multiply by the transpose of the inverse (9 multiplications, 6 additions)
+  /* Multiply by the transpose of the inverse
+     (9 multiplications, 6 additions) */
   dmnsn_vector r;
   r.x = Tinv.n[0][0]*v.x + Tinv.n[1][0]*v.y + Tinv.n[2][0]*v.z;
   r.y = Tinv.n[0][1]*v.x + Tinv.n[1][1]*v.y + Tinv.n[2][1]*v.z;
@@ -419,7 +430,7 @@ dmnsn_transform_normal(dmnsn_matrix Tinv, dmnsn_vector v)
   return r;
 }
 
-/// Transform a bounding box by a matrix.
+/** Transform a bounding box by a matrix. */
 dmnsn_bounding_box dmnsn_transform_bounding_box(dmnsn_matrix T,
                                                 dmnsn_bounding_box box);
 
@@ -431,7 +442,7 @@ dmnsn_bounding_box dmnsn_transform_bounding_box(dmnsn_matrix T,
 DMNSN_INLINE dmnsn_line
 dmnsn_transform_line(dmnsn_matrix T, dmnsn_line l)
 {
-  // 18 multiplications, 24 additions
+  /* 18 multiplications, 24 additions */
   dmnsn_line ret;
   ret.x0 = dmnsn_transform_point(T, l.x0);
   ret.n  = dmnsn_transform_direction(T, l.n);
@@ -448,7 +459,7 @@ dmnsn_line_point(dmnsn_line l, double t)
   return dmnsn_vector_add(l.x0, dmnsn_vector_mul(t, l.n));
 }
 
-/// Add epsilon*l.n to l.x0, to avoid self-intersections.
+/** Add epsilon*l.n to l.x0, to avoid self-intersections. */
 DMNSN_INLINE dmnsn_line
 dmnsn_line_add_epsilon(dmnsn_line l)
 {
@@ -477,7 +488,7 @@ dmnsn_symmetric_bounding_box(dmnsn_vector r)
   return box;
 }
 
-/// Return whether \p p is within the axis-aligned bounding box.
+/** Return whether \p p is within the axis-aligned bounding box. */
 DMNSN_INLINE bool
 dmnsn_bounding_box_contains(dmnsn_bounding_box box, dmnsn_vector p)
 {
@@ -485,11 +496,11 @@ dmnsn_bounding_box_contains(dmnsn_bounding_box box, dmnsn_vector p)
       && (p.x <= box.max.x && p.y <= box.max.y && p.z <= box.max.z);
 }
 
-/// Return whether a bounding box is infinite.
+/** Return whether a bounding box is infinite. */
 DMNSN_INLINE bool
 dmnsn_bounding_box_is_infinite(dmnsn_bounding_box box)
 {
-  return box.min.x == -INFINITY;
+  return box.min.x == -DMNSN_INFINITY;
 }
 
 /**
@@ -508,21 +519,32 @@ dmnsn_bounding_box_swallow(dmnsn_bounding_box box, dmnsn_vector point)
   return ret;
 }
 
-/// Return whether a vector contains any NaN components.
+/** Return whether a scalar is NaN. */
+DMNSN_INLINE bool
+dmnsn_isnan(double n)
+{
+#if DMNSN_C99
+  return isnan(n);
+#else
+  return n != n;
+#endif
+}
+
+/** Return whether a vector contains any NaN components. */
 DMNSN_INLINE bool
 dmnsn_vector_isnan(dmnsn_vector v)
 {
-  return isnan(v.x) || isnan(v.y) || isnan(v.z);
+  return dmnsn_isnan(v.x) || dmnsn_isnan(v.y) || dmnsn_isnan(v.z);
 }
 
-/// Return whether a matrix contains any NaN components.
+/** Return whether a matrix contains any NaN components. */
 DMNSN_INLINE bool
 dmnsn_matrix_isnan(dmnsn_matrix m)
 {
   size_t i, j;
   for (i = 0; i < 3; ++i) {
     for (j = 0; j < 4; ++j) {
-      if (isnan(m.n[i][j])) {
+      if (dmnsn_isnan(m.n[i][j])) {
         return true;
       }
     }
@@ -530,14 +552,14 @@ dmnsn_matrix_isnan(dmnsn_matrix m)
   return false;
 }
 
-/// Return whether a line contains any NaN entries.
+/** Return whether a line contains any NaN entries. */
 DMNSN_INLINE bool
 dmnsn_line_isnan(dmnsn_line l)
 {
   return dmnsn_vector_isnan(l.x0) || dmnsn_vector_isnan(l.n);
 }
 
-/// Return whether a bounding box has any NaN components.
+/** Return whether a bounding box has any NaN components. */
 DMNSN_INLINE bool
 dmnsn_bounding_box_isnan(dmnsn_bounding_box box)
 {
diff --git a/libdimension/dimension/interior.h b/libdimension/dimension/interior.h
index 006e88d..0ff697d 100644
--- a/libdimension/dimension/interior.h
+++ b/libdimension/dimension/interior.h
@@ -23,9 +23,9 @@
  * Object interiors.
  */
 
-/// An interior.
+/** An interior. */
 typedef struct dmnsn_interior {
-  double ior; ///< Refractive index.
+  double ior; /**< Refractive index. */
 } dmnsn_interior;
 
 /**
diff --git a/libdimension/dimension/light.h b/libdimension/dimension/light.h
index 82b72b4..218611d 100644
--- a/libdimension/dimension/light.h
+++ b/libdimension/dimension/light.h
@@ -25,7 +25,7 @@
 
 #include <stdbool.h>
 
-// Forward-declar dmnsn_light
+/* Forward-declar dmnsn_light */
 typedef struct dmnsn_light dmnsn_light;
 
 /**
@@ -54,12 +54,12 @@ typedef dmnsn_color dmnsn_light_illumination_fn(const dmnsn_light *light,
  */
 typedef bool dmnsn_light_shadow_fn(const dmnsn_light *light, double t);
 
-/// A light.
+/** A light. */
 struct dmnsn_light {
-  // Callbacks
-  dmnsn_light_direction_fn *direction_fn; ///< Direction callback.
-  dmnsn_light_illumination_fn *illumination_fn; ///< Illumination callback.
-  dmnsn_light_shadow_fn *shadow_fn; ///< Shadow callback.
+  /* Callbacks */
+  dmnsn_light_direction_fn *direction_fn; /**< Direction callback. */
+  dmnsn_light_illumination_fn *illumination_fn; /**< Illumination callback. */
+  dmnsn_light_shadow_fn *shadow_fn; /**< Shadow callback. */
 };
 
 /**
diff --git a/libdimension/dimension/malloc.h b/libdimension/dimension/malloc.h
index e7dcd4a..742e3a2 100644
--- a/libdimension/dimension/malloc.h
+++ b/libdimension/dimension/malloc.h
@@ -25,7 +25,7 @@
  * fails, they instead call dmnsn_error().
  */
 
-#include <stddef.h> // For size_t
+#include <stddef.h> /* For size_t */
 
 /**
  * Allocate some memory.  Always use dmnsn_free() to free this memory, never
diff --git a/libdimension/dimension/map.h b/libdimension/dimension/map.h
index f5642b5..7229a24 100644
--- a/libdimension/dimension/map.h
+++ b/libdimension/dimension/map.h
@@ -23,7 +23,7 @@
  * Generic maps (backend for pigment_maps, etc.).
  */
 
-/// A map.
+/** A map. */
 typedef struct dmnsn_map dmnsn_map;
 
 /**
diff --git a/libdimension/dimension/object.h b/libdimension/dimension/object.h
index 1887119..c8e9d86 100644
--- a/libdimension/dimension/object.h
+++ b/libdimension/dimension/object.h
@@ -25,18 +25,18 @@
 
 #include <stdbool.h>
 
-// Forward-declare dmnsn_object
+/* Forward-declare dmnsn_object */
 typedef struct dmnsn_object dmnsn_object;
 
-/// A type to represent a ray-object intersection.
+/** A type to represent a ray-object intersection. */
 typedef struct dmnsn_intersection {
-  dmnsn_line ray; ///< The ray that intersected.
-  double t;       ///< The line index that intersected.
+  dmnsn_line ray; /**< The ray that intersected. */
+  double t;       /**< The line index that intersected. */
 
-  /// The surface normal at the intersection point.
+  /** The surface normal at the intersection point. */
   dmnsn_vector normal;
 
-  /// The object of intersection.
+  /** The object of intersection. */
   const dmnsn_object *object;
 } dmnsn_intersection;
 
@@ -71,32 +71,32 @@ typedef dmnsn_bounding_box dmnsn_object_bounding_fn(const dmnsn_object *object,
  */
 typedef void dmnsn_object_precompute_fn(dmnsn_object *object);
 
-/// Object callbacks.
+/** Object callbacks. */
 typedef struct dmnsn_object_vtable {
-  dmnsn_object_intersection_fn *intersection_fn; ///< Intersection callback.
-  dmnsn_object_inside_fn *inside_fn; ///< Inside callback.
-  dmnsn_object_bounding_fn *bounding_fn; ///< Bounding callback.
-  dmnsn_object_precompute_fn *precompute_fn; ///< Precomputation callback.
+  dmnsn_object_intersection_fn *intersection_fn; /**< Intersection callback. */
+  dmnsn_object_inside_fn *inside_fn; /**< Inside callback. */
+  dmnsn_object_bounding_fn *bounding_fn; /**< Bounding callback. */
+  dmnsn_object_precompute_fn *precompute_fn; /**< Precomputation callback. */
 } dmnsn_object_vtable;
 
-/// An object.
+/** An object. */
 struct dmnsn_object {
-  const dmnsn_object_vtable *vtable; ///< Callbacks.
+  const dmnsn_object_vtable *vtable; /**< Callbacks. */
 
-  dmnsn_texture *texture;  ///< Surface properties.
-  dmnsn_interior *interior; ///< Interior properties.
+  dmnsn_texture *texture;  /**< Surface properties. */
+  dmnsn_interior *interior; /**< Interior properties. */
 
-  dmnsn_matrix trans; ///< Transformation matrix.
-  dmnsn_matrix intrinsic_trans; ///< Transformations intrinsic to the object.
+  dmnsn_matrix trans; /**< Transformation matrix. */
+  dmnsn_matrix intrinsic_trans; /**< Transformations intrinsic to the object. */
 
-  dmnsn_array *children; ///< Child objects.
-  bool split_children;   ///< Whether the child objects can be split.
+  dmnsn_array *children; /**< Child objects. */
+  bool split_children;   /**< Whether the child objects can be split. */
 
-  // Precomputed values
-  bool precomputed; ///< @internal Whether the object is precomputed yet.
-  dmnsn_matrix trans_inv; ///< Inverse of the transformation matrix.
-  dmnsn_matrix pigment_trans; ///< Inverse transformation for the texture.
-  dmnsn_bounding_box bounding_box; ///< Bounding box in world coordinates.
+  /* Precomputed values */
+  bool precomputed; /**< @internal Whether the object is precomputed yet. */
+  dmnsn_matrix trans_inv; /**< Inverse of the transformation matrix. */
+  dmnsn_matrix pigment_trans; /**< Inverse transformation for the texture. */
+  dmnsn_bounding_box bounding_box; /**< Bounding box in world coordinates. */
 };
 
 /**
@@ -132,7 +132,7 @@ dmnsn_object_intersection(const dmnsn_object *object, dmnsn_line line,
   dmnsn_line line_trans = dmnsn_transform_line(object->trans_inv, line);
   intersection->object = NULL;
   if (object->vtable->intersection_fn(object, line_trans, intersection)) {
-    // Get us back into world coordinates
+    /* Get us back into world coordinates */
     intersection->ray = line;
     intersection->normal = dmnsn_vector_normalized(
       dmnsn_transform_normal(object->trans_inv, intersection->normal)
@@ -141,9 +141,8 @@ dmnsn_object_intersection(const dmnsn_object *object, dmnsn_line line,
       intersection->object = object;
     }
 
-    dmnsn_assert(!isnan(intersection->t), "Intersection point is NaN.");
-    dmnsn_assert(!dmnsn_vector_isnan(intersection->normal),
-                 "Intersection normal is NaN.");
+    dmnsn_assert(!dmnsn_isnan(intersection->t), "Intersection point is NaN.");
+    dmnsn_assert(!dmnsn_vector_isnan(intersection->normal), "Intersection normal is NaN.");
 
     return true;
   } else {
diff --git a/libdimension/dimension/pattern.h b/libdimension/dimension/pattern.h
index f1276ec..2caed07 100644
--- a/libdimension/dimension/pattern.h
+++ b/libdimension/dimension/pattern.h
@@ -24,7 +24,7 @@
  * used for pigments and normals.
  */
 
-// Forward-declare dmnsn_pattern
+/* Forward-declare dmnsn_pattern */
 typedef struct dmnsn_pattern dmnsn_pattern;
 
 /**
@@ -35,9 +35,9 @@ typedef struct dmnsn_pattern dmnsn_pattern;
  */
 typedef double dmnsn_pattern_fn(const dmnsn_pattern *pattern, dmnsn_vector v);
 
-/// A pattern.
+/** A pattern. */
 struct dmnsn_pattern {
-  dmnsn_pattern_fn *pattern_fn; ///< The pattern callback.
+  dmnsn_pattern_fn *pattern_fn; /**< The pattern callback. */
 };
 
 /**
diff --git a/libdimension/dimension/pigment.h b/libdimension/dimension/pigment.h
index 05bc6f6..14d8bae 100644
--- a/libdimension/dimension/pigment.h
+++ b/libdimension/dimension/pigment.h
@@ -23,7 +23,7 @@
  * Object pigments.
  */
 
-// Forward-declare dmnsn_pigment
+/* Forward-declare dmnsn_pigment */
 typedef struct dmnsn_pigment dmnsn_pigment;
 
 /**
@@ -41,18 +41,18 @@ typedef dmnsn_tcolor dmnsn_pigment_fn(const dmnsn_pigment *pigment,
  */
 typedef void dmnsn_pigment_initialize_fn(dmnsn_pigment *pigment);
 
-/// A pigment.
+/** A pigment. */
 struct dmnsn_pigment {
-  dmnsn_pigment_fn *pigment_fn; ///< The pigment callback.
-  dmnsn_pigment_initialize_fn *initialize_fn; ///< The initializer callback.
+  dmnsn_pigment_fn *pigment_fn; /**< The pigment callback. */
+  dmnsn_pigment_initialize_fn *initialize_fn; /**< The initializer callback. */
 
-  dmnsn_matrix trans; ///< Transformation matrix.
-  dmnsn_matrix trans_inv; ///< The inverse of the transformation matrix.
+  dmnsn_matrix trans; /**< Transformation matrix. */
+  dmnsn_matrix trans_inv; /**< The inverse of the transformation matrix. */
 
-  /// Quick color -- used for low-quality renders.
+  /** Quick color -- used for low-quality renders. */
   dmnsn_tcolor quick_color;
 
-  bool initialized; /// @internal Whether the pigment is initialized.
+  bool initialized; /** @internal Whether the pigment is initialized. */
 };
 
 /**
diff --git a/libdimension/dimension/pigments.h b/libdimension/dimension/pigments.h
index edaf2b4..100016d 100644
--- a/libdimension/dimension/pigments.h
+++ b/libdimension/dimension/pigments.h
@@ -44,8 +44,8 @@ dmnsn_pigment *dmnsn_new_canvas_pigment(dmnsn_pool *pool, dmnsn_canvas *canvas);
  * Pigment map flags.
  */
 typedef enum dmnsn_pigment_map_flags {
-  DMNSN_PIGMENT_MAP_REGULAR, ///< Calculate linear color gradients.
-  DMNSN_PIGMENT_MAP_SRGB ///< Calculate sRGB color gradients.
+  DMNSN_PIGMENT_MAP_REGULAR, /**< Calculate linear color gradients. */
+  DMNSN_PIGMENT_MAP_SRGB /**< Calculate sRGB color gradients. */
 } dmnsn_pigment_map_flags;
 
 /**
diff --git a/libdimension/dimension/pool.h b/libdimension/dimension/pool.h
index a744398..164bbbc 100644
--- a/libdimension/dimension/pool.h
+++ b/libdimension/dimension/pool.h
@@ -25,9 +25,9 @@
  * once once a scene is rendered (for example).
  */
 
-#include <stddef.h> // For size_t
+#include <stddef.h> /* For size_t */
 
-// Forward-declare dmnsn_pool.
+/* Forward-declare dmnsn_pool. */
 typedef struct dmnsn_pool dmnsn_pool;
 
 /**
diff --git a/libdimension/dimension/scene.h b/libdimension/dimension/scene.h
index b9f8c36..dd0c1ba 100644
--- a/libdimension/dimension/scene.h
+++ b/libdimension/dimension/scene.h
@@ -23,62 +23,62 @@
  * Entire scenes.
  */
 
-/// Render quality flags.
+/** Render quality flags. */
 enum {
-  DMNSN_RENDER_NONE         = 0,      ///< Render nothing.
-  DMNSN_RENDER_PIGMENT      = 1 << 0, ///< Render pigments.
-  DMNSN_RENDER_LIGHTS       = 1 << 1, ///< Render lights and shadows.
-  DMNSN_RENDER_FINISH       = 1 << 2, ///< Render object finishes.
-  DMNSN_RENDER_TRANSPARENCY = 1 << 3, ///< Render transparency/refraction.
-  DMNSN_RENDER_REFLECTION   = 1 << 4, ///< Render specular reflection.
-  DMNSN_RENDER_FULL         = ~DMNSN_RENDER_NONE ///< Render everything.
+  DMNSN_RENDER_NONE         = 0,      /**< Render nothing. */
+  DMNSN_RENDER_PIGMENT      = 1 << 0, /**< Render pigments. */
+  DMNSN_RENDER_LIGHTS       = 1 << 1, /**< Render lights and shadows. */
+  DMNSN_RENDER_FINISH       = 1 << 2, /**< Render object finishes. */
+  DMNSN_RENDER_TRANSPARENCY = 1 << 3, /**< Render transparency/refraction. */
+  DMNSN_RENDER_REFLECTION   = 1 << 4, /**< Render specular reflection. */
+  DMNSN_RENDER_FULL         = ~DMNSN_RENDER_NONE /**< Render everything. */
 };
 
-/// Render quality.
+/** Render quality. */
 typedef unsigned int dmnsn_quality;
 
-/// An entire scene.
+/** An entire scene. */
 typedef struct dmnsn_scene {
-  // World attributes
-  dmnsn_pigment *background;        ///< Background pigment.
-  dmnsn_texture *default_texture;   ///< Default object texture.
-  dmnsn_interior *default_interior; ///< Default object interior.
+  /* World attributes */
+  dmnsn_pigment *background;        /**< Background pigment. */
+  dmnsn_texture *default_texture;   /**< Default object texture. */
+  dmnsn_interior *default_interior; /**< Default object interior. */
 
-  /// Canvas.
+  /** Canvas. */
   dmnsn_canvas *canvas;
 
-  // Support for rendering image subregions.
-  size_t region_x; ///< The x position of the canvas in the broader image.
-  size_t region_y; ///< The y position of the canvas in the broader image.
-  size_t outer_width; ///< Width of the broader image.
-  size_t outer_height; ///< Height of the broader image.
+  /* Support for rendering image subregions. */
+  size_t region_x; /**< The x position of the canvas in the broader image. */
+  size_t region_y; /**< The y position of the canvas in the broader image. */
+  size_t outer_width; /**< Width of the broader image. */
+  size_t outer_height; /**< Height of the broader image. */
 
-  /// Objects.
+  /** Objects. */
   dmnsn_array *objects;
 
-  /// Lights.
+  /** Lights. */
   dmnsn_array *lights;
 
-  /// Camera.
+  /** Camera. */
   dmnsn_camera *camera;
 
-  /// Render quality.
+  /** Render quality. */
   dmnsn_quality quality;
 
-  /// Recursion limit.
+  /** Recursion limit. */
   unsigned int reclimit;
 
-  /// Adaptive depth control bailout.
+  /** Adaptive depth control bailout. */
   double adc_bailout;
 
-  /// Number of parallel threads.
+  /** Number of parallel threads. */
   unsigned int nthreads;
 
-  /// Timers.
+  /** Timers. */
   dmnsn_timer bounding_timer;
   dmnsn_timer render_timer;
 
-  bool initialized; ///< @internal Whether the scene is initialized.
+  bool initialized; /**< @internal Whether the scene is initialized. */
 } dmnsn_scene;
 
 /**
diff --git a/libdimension/dimension/tcolor.h b/libdimension/dimension/tcolor.h
index b50178d..4432dd1 100644
--- a/libdimension/dimension/tcolor.h
+++ b/libdimension/dimension/tcolor.h
@@ -23,19 +23,19 @@
  * Colors with transparency information.
  */
 
-/// A transparent color.
+/** A transparent color. */
 typedef struct dmnsn_tcolor {
-  dmnsn_color c; ///< Color.
-  double T;      ///< Transparency.
-  double F;      ///< Proportion of filtered transparency.
+  dmnsn_color c; /**< Color. */
+  double T;      /**< Transparency. */
+  double F;      /**< Proportion of filtered transparency. */
 } dmnsn_tcolor;
 
-/// A standard format string for colors.
+/** A standard format string for colors. */
 #define DMNSN_TCOLOR_FORMAT "TColor<%g, %g, %g, %g, %g>"
-/// The appropriate arguements to printf() a color.
+/** The appropriate arguements to printf() a color. */
 #define DMNSN_TCOLOR_PRINTF(tc) (tc).c.R, (tc).c.G, (tc).c.B, (tc).T, (tc).F
 
-/// Create a tcolor.
+/** Create a tcolor. */
 DMNSN_INLINE dmnsn_tcolor
 dmnsn_new_tcolor(dmnsn_color c, double T, double F)
 {
@@ -43,10 +43,10 @@ dmnsn_new_tcolor(dmnsn_color c, double T, double F)
   return ret;
 }
 
-/// Convert a dmnsn_color into a dmnsn_tcolor.
+/** Convert a dmnsn_color into a dmnsn_tcolor. */
 #define DMNSN_TCOLOR(c) dmnsn_new_tcolor(c, 0.0, 0.0)
 
-/// Create a tcolor with individually-specified components.
+/** Create a tcolor with individually-specified components. */
 DMNSN_INLINE dmnsn_tcolor
 dmnsn_new_tcolor5(double R, double G, double B, double T, double F)
 {
@@ -54,7 +54,7 @@ dmnsn_new_tcolor5(double R, double G, double B, double T, double F)
   return ret;
 }
 
-/// Return the color at \p n on a gradient from \p c1 at 0 to \p c2 at 1.
+/** Return the color at \p n on a gradient from \p c1 at 0 to \p c2 at 1. */
 DMNSN_INLINE dmnsn_tcolor
 dmnsn_tcolor_gradient(dmnsn_tcolor c1, dmnsn_tcolor c2, double n)
 {
@@ -65,7 +65,7 @@ dmnsn_tcolor_gradient(dmnsn_tcolor c1, dmnsn_tcolor c2, double n)
   );
 }
 
-/// Filter \p light through \p filter.
+/** Filter \p light through \p filter. */
 DMNSN_INLINE dmnsn_color
 dmnsn_tcolor_filter(dmnsn_color light, dmnsn_tcolor filter)
 {
@@ -75,7 +75,7 @@ dmnsn_tcolor_filter(dmnsn_color light, dmnsn_tcolor filter)
   return dmnsn_color_add(filtered, transmitted);
 }
 
-/// Remove the filtered component of a tcolor.
+/** Remove the filtered component of a tcolor. */
 DMNSN_INLINE dmnsn_tcolor
 dmnsn_tcolor_remove_filter(dmnsn_tcolor tcolor)
 {
@@ -89,7 +89,7 @@ dmnsn_tcolor_remove_filter(dmnsn_tcolor tcolor)
   return tcolor;
 }
 
-/// Saturate the tcolor components to [0.0, 1.0].
+/** Saturate the tcolor components to [0.0, 1.0]. */
 DMNSN_INLINE dmnsn_tcolor
 dmnsn_tcolor_saturate(dmnsn_tcolor tcolor)
 {
@@ -99,14 +99,14 @@ dmnsn_tcolor_saturate(dmnsn_tcolor tcolor)
   return tcolor;
 }
 
-/// Return whether a tcolor contains any NaN components.
+/** Return whether a tcolor contains any NaN components. */
 DMNSN_INLINE bool
 dmnsn_tcolor_isnan(dmnsn_tcolor tcolor)
 {
-  return dmnsn_color_isnan(tcolor.c) || isnan(tcolor.T) || isnan(tcolor.F);
+  return dmnsn_color_isnan(tcolor.c) || dmnsn_isnan(tcolor.T) || dmnsn_isnan(tcolor.F);
 }
 
-// Standard tcolors
+/* Standard tcolors */
 
-/// Clear.
+/** Clear. */
 #define dmnsn_clear dmnsn_new_tcolor5(0.0, 0.0, 0.0, 1.0, 0.0)
diff --git a/libdimension/dimension/texture.h b/libdimension/dimension/texture.h
index 58f5a80..df08a4a 100644
--- a/libdimension/dimension/texture.h
+++ b/libdimension/dimension/texture.h
@@ -23,15 +23,15 @@
  * Object textures.
  */
 
-/// A complete texture.
+/** A complete texture. */
 typedef struct {
-  dmnsn_pigment *pigment; ///< Pigment.
-  dmnsn_finish finish;    ///< Finish.
+  dmnsn_pigment *pigment; /**< Pigment. */
+  dmnsn_finish finish;    /**< Finish. */
 
-  dmnsn_matrix trans;     ///< Transformation matrix.
-  dmnsn_matrix trans_inv; ///< The inverse of the transformation matrix.
+  dmnsn_matrix trans;     /**< Transformation matrix. */
+  dmnsn_matrix trans_inv; /**< The inverse of the transformation matrix. */
 
-  bool initialized; ///< @internal Whether the texture is initialized yet.
+  bool initialized; /**< @internal Whether the texture is initialized yet. */
 } dmnsn_texture;
 
 /**
diff --git a/libdimension/dimension/timer.h b/libdimension/dimension/timer.h
index be1f3c0..55d66ff 100644
--- a/libdimension/dimension/timer.h
+++ b/libdimension/dimension/timer.h
@@ -23,14 +23,14 @@
  * A platform-agnostic timer abstraction.
  */
 
-/// A platform-agnotic timer.
+/** A platform-agnotic timer. */
 typedef struct dmnsn_timer {
-  double real;   ///< Wall-clock time.
-  double user;   ///< Time spent executing.
-  double system; ///< Time spent waiting for the system.
+  double real;   /**< Wall-clock time. */
+  double user;   /**< Time spent executing. */
+  double system; /**< Time spent waiting for the system. */
 } dmnsn_timer;
 
-/// A standard format string for timers.
+/** A standard format string for timers. */
 #define DMNSN_TIMER_FORMAT "%.2fs (user: %.2fs; system: %.2fs)"
 /**
  * The appropriate arguments to printf() a timer.  For example:
diff --git a/libdimension/tests/Makefile.am b/libdimension/tests/Makefile.am
index a2d78ba..0349850 100644
--- a/libdimension/tests/Makefile.am
+++ b/libdimension/tests/Makefile.am
@@ -33,6 +33,7 @@ check_PROGRAMS    = warning.test                                               \
                     png.test                                                   \
                     gl.test                                                    \
                     render.test                                                \
+                    c89.test                                                   \
                     c99.test                                                   \
                     cxx.test
 TESTS             = $(check_PROGRAMS)
@@ -96,6 +97,11 @@ gl_test_LDADD   = libdimension-tests.la
 render_test_SOURCES = render.c
 render_test_LDADD   = libdimension-tests.la
 
+c89_test_SOURCES = c89.c
+c89_test_LDADD   = libdimension-tests.la
+
+c89.o: CFLAGS += -std=c89 -Wpedantic
+
 c99_test_SOURCES = c99.c
 c99_test_LDADD   = libdimension-tests.la
 
diff --git a/libdimension/tests/c89.c b/libdimension/tests/c89.c
new file mode 100644
index 0000000..9393184
--- /dev/null
+++ b/libdimension/tests/c89.c
@@ -0,0 +1,32 @@
+/*************************************************************************
+ * Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com>          *
+ *                                                                       *
+ * This file is part of The Dimension Test Suite.                        *
+ *                                                                       *
+ * The Dimension Test Suite is free software; you can redistribute it    *
+ * and/or modify it under the terms of the GNU General Public License as *
+ * published by the Free Software Foundation; either version 3 of the    *
+ * License, or (at your option) any later version.                       *
+ *                                                                       *
+ * The Dimension Test Suite is distributed in the hope that it will be   *
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty   *
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
+ * General Public License for more details.                              *
+ *                                                                       *
+ * You should have received a copy of the GNU General Public License     *
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+/**
+ * @file
+ * Check C89 compliance of headers.
+ */
+
+#include "dimension.h"
+#include <stddef.h>
+
+int
+main(void)
+{
+  return EXIT_SUCCESS;
+}