Rudimentary light/shadow handling.

5 files changed, 109 insertions, 22 deletions

diff --git a/libdimension/color.c b/libdimension/color.c
index 7fb73ed..374a0a0 100644
--- a/libdimension/color.c
+++ b/libdimension/color.c
@@ -263,17 +263,14 @@ dmnsn_sRGB_from_color(dmnsn_color color)
 dmnsn_color
 dmnsn_color_add(dmnsn_color color1, dmnsn_color color2)
 {
-  dmnsn_CIE_Lab Lab, Lab1, Lab2;
-  dmnsn_color ret;
-
-  Lab1 = dmnsn_Lab_from_color(color1, dmnsn_whitepoint);
-  Lab2 = dmnsn_Lab_from_color(color2, dmnsn_whitepoint);
+  dmnsn_CIE_Lab Lab1 = dmnsn_Lab_from_color(color1, dmnsn_whitepoint);
+  dmnsn_CIE_Lab Lab2 = dmnsn_Lab_from_color(color2, dmnsn_whitepoint);
 
-  Lab.L = Lab1.L + Lab2.L;
-  Lab.a = Lab1.a + Lab2.a;
-  Lab.b = Lab1.b + Lab2.b;
+  dmnsn_CIE_Lab Lab = { .L = Lab1.L + Lab2.L,
+                        .a = Lab1.a + Lab2.a,
+                        .b = Lab1.b + Lab2.b };
 
-  ret = dmnsn_color_from_Lab(Lab, dmnsn_whitepoint);
+  dmnsn_color ret = dmnsn_color_from_Lab(Lab, dmnsn_whitepoint);
   /* Weighted average of transparencies by intensity */
   ret.filter = (Lab1.L*color1.filter + Lab2.L*color2.filter)/Lab.L;
   ret.trans  = (Lab1.L*color1.trans  + Lab2.L*color2.trans)/Lab.L;
@@ -281,6 +278,47 @@ dmnsn_color_add(dmnsn_color color1, dmnsn_color color2)
   return ret;
 }
 
+/* Multiply a color by a scalar */
+dmnsn_color
+dmnsn_color_mul(double n, dmnsn_color color)
+{
+  dmnsn_CIE_Lab Lab = dmnsn_Lab_from_color(color, dmnsn_whitepoint);
+  double LabL = Lab.L;
+  Lab.L *= n;
+  Lab.a *= n;
+  Lab.b *= n;
+
+  dmnsn_color ret = dmnsn_color_from_Lab(Lab, dmnsn_whitepoint);
+  ret.filter = color.filter;
+  ret.trans  = color.trans;
+
+  return ret;
+}
+
+/* Illuminates `color' with `light' */
+dmnsn_color
+dmnsn_color_illuminate(dmnsn_color light, dmnsn_color color)
+{
+  dmnsn_CIE_Lab Lab1 = dmnsn_Lab_from_color(light, dmnsn_whitepoint);
+  dmnsn_CIE_Lab Lab2 = dmnsn_Lab_from_color(color, dmnsn_whitepoint);
+
+  double dot  = Lab1.L*Lab2.L + Lab1.a*Lab2.a + Lab1.b*Lab2.b;
+  double norm = sqrt(Lab2.L*Lab2.L + Lab2.a*Lab2.a + Lab2.b*Lab2.b);
+
+  if (norm == 0.0)
+    return dmnsn_black;
+
+  dmnsn_CIE_Lab Lab = { .L = dot*Lab2.L/norm/100.0,
+                        .a = dot*Lab2.a/norm,
+                        .b = dot*Lab2.b/norm };
+
+  dmnsn_color ret = dmnsn_color_from_Lab(Lab, dmnsn_whitepoint);
+  ret.filter = color.filter;
+  ret.trans  = color.trans;
+
+  return ret;
+}
+
 /* Find the perceptual difference between two colors, using CIE L*a*b*. */
 double
 dmnsn_color_difference(dmnsn_color color1, dmnsn_color color2)
diff --git a/libdimension/dimension/color.h b/libdimension/dimension/color.h
index ab2ea04..a72de98 100644
--- a/libdimension/dimension/color.h
+++ b/libdimension/dimension/color.h
@@ -80,10 +80,10 @@ dmnsn_CIE_Lab dmnsn_Lab_from_color(dmnsn_color color, dmnsn_CIE_XYZ white);
 dmnsn_CIE_Luv dmnsn_Luv_from_color(dmnsn_color color, dmnsn_CIE_XYZ white);
 dmnsn_sRGB    dmnsn_sRGB_from_color(dmnsn_color color);
 
-/* Perceptually correct color combination */
+/* Perceptual color manipulation */
 dmnsn_color dmnsn_color_add(dmnsn_color color1, dmnsn_color color2);
-
-/* Perceptual color difference */
+dmnsn_color dmnsn_color_mul(double n, dmnsn_color color);
+dmnsn_color dmnsn_color_illuminate(dmnsn_color light, dmnsn_color color);
 double dmnsn_color_difference(dmnsn_color color1, dmnsn_color color2);
 
 #endif /* DIMENSION_COLOR_H */
diff --git a/libdimension/dimension/scene.h b/libdimension/dimension/scene.h
index 8c9c705..e3f9662 100644
--- a/libdimension/dimension/scene.h
+++ b/libdimension/dimension/scene.h
@@ -29,6 +29,7 @@ typedef enum {
   DMNSN_RENDER_NONE,
   DMNSN_RENDER_OBJECTS,
   DMNSN_RENDER_PIGMENT,
+  DMNSN_RENDER_LIGHTS,
   DMNSN_RENDER_FULL
 } dmnsn_quality;
 
diff --git a/libdimension/raytrace.c b/libdimension/raytrace.c
index 6cb6d8b..da78411 100644
--- a/libdimension/raytrace.c
+++ b/libdimension/raytrace.c
@@ -259,11 +259,7 @@ static dmnsn_color
 dmnsn_raytrace_shoot(dmnsn_line ray, dmnsn_scene *scene,
                      dmnsn_kD_splay_tree *kD_splay_tree, dmnsn_color color)
 {
-  dmnsn_intersection *intersection;
-  const dmnsn_texture *texture;
-  const dmnsn_pigment *pigment;
-
-  intersection = dmnsn_kD_splay_search(kD_splay_tree, ray);
+  dmnsn_intersection *intersection = dmnsn_kD_splay_search(kD_splay_tree, ray);
 
   if (intersection) {
     /* Default to black if we have no texture/pigment */
@@ -271,13 +267,15 @@ dmnsn_raytrace_shoot(dmnsn_line ray, dmnsn_scene *scene,
 
     if (scene->quality >= DMNSN_RENDER_PIGMENT) {
       /* Use the default texture if given a NULL texture */
-      texture = intersection->texture ? intersection->texture
-                                      : scene->default_texture;
+      const dmnsn_texture *texture
+        = intersection->texture ? intersection->texture
+                                : scene->default_texture;
 
       if (texture) {
         /* Use the default pigment if given a NULL pigment */
-        pigment = texture->pigment ? texture->pigment
-                                   : scene->default_texture->pigment;
+        const dmnsn_pigment *pigment
+          = texture->pigment ? texture->pigment
+                             : scene->default_texture->pigment;
 
         if (pigment) {
           color = (*pigment->pigment_fn)(
@@ -288,6 +286,56 @@ dmnsn_raytrace_shoot(dmnsn_line ray, dmnsn_scene *scene,
       }
     }
 
+    if (scene->quality >= DMNSN_RENDER_LIGHTS) {
+      dmnsn_color illum = dmnsn_color_mul(0.3, color);
+
+      const dmnsn_light *light;
+      unsigned int i;
+
+      for (i = 0; i < dmnsn_array_size(scene->lights); ++i) {
+        dmnsn_array_get(scene->lights, i, &light);
+        dmnsn_vector x0 = dmnsn_line_point(ray, intersection->t);
+        dmnsn_line shadow_ray = dmnsn_line_construct(
+          dmnsn_vector_add(
+            x0,
+            dmnsn_vector_mul(1.0e-6, dmnsn_vector_sub(light->x0, x0))
+          ),
+          dmnsn_vector_sub(light->x0, x0)
+        );
+
+        dmnsn_intersection *shadow_caster
+          = dmnsn_kD_splay_search(kD_splay_tree, shadow_ray);
+
+        if (!shadow_caster || shadow_caster->t > 1.0) {
+          dmnsn_vector object_normal = x0;
+          dmnsn_vector normal = dmnsn_vector_normalize(
+            dmnsn_vector_add(
+              dmnsn_vector_normalize(dmnsn_vector_sub(ray.x0, x0)),
+              dmnsn_vector_normalize(dmnsn_vector_sub(light->x0, x0))
+            )
+          );
+
+          illum = dmnsn_color_add(
+            dmnsn_color_mul(
+              dmnsn_vector_dot(normal, object_normal),
+              dmnsn_color_illuminate((*light->light_fn)(light, x0), color)
+            ),
+            illum
+          );
+          illum = dmnsn_color_add(
+            dmnsn_color_mul(
+              0.1*dmnsn_vector_dot(normal, object_normal),
+              dmnsn_color_illuminate((*light->light_fn)(light, x0), dmnsn_white)
+            ),
+            illum
+          );
+        }
+
+        dmnsn_delete_intersection(shadow_caster);
+        color = illum;
+      }
+    }
+
     /* Delete the intersection */
     dmnsn_delete_intersection(intersection);
   }
diff --git a/tests/libdimension/tests.c b/tests/libdimension/tests.c
index 5a0b4cf..1257219 100644
--- a/tests/libdimension/tests.c
+++ b/tests/libdimension/tests.c
@@ -116,7 +116,7 @@ dmnsn_new_default_scene()
   /* Now make a light */
 
   dmnsn_light *light = dmnsn_new_point_light(
-    dmnsn_vector_construct(0.0, 3.0, 0.0),
+    dmnsn_vector_construct(-5.0, 20.0, -5.0),
     dmnsn_white
   );
   if (!light) {