Round correctly when converting colors to integers.

4 files changed, 35 insertions, 24 deletions

diff --git a/libdimension/canvas_pigment.c b/libdimension/canvas_pigment.c
index 3ab9de4..8a7e7d3 100644
--- a/libdimension/canvas_pigment.c
+++ b/libdimension/canvas_pigment.c
@@ -1,5 +1,5 @@
 /*************************************************************************
- * Copyright (C) 2010 Tavian Barnes <tavianator@tavianator.com>          *
+ * Copyright (C) 2010-2011 Tavian Barnes <tavianator@tavianator.com>     *
  *                                                                       *
  * This file is part of The Dimension Library.                           *
  *                                                                       *
@@ -31,8 +31,8 @@ dmnsn_canvas_pigment_fn(const dmnsn_pigment *pigment, dmnsn_vector v)
 {
   dmnsn_canvas *canvas = pigment->ptr;
 
-  int x = (fmod(v.x, 1.0) + 1.0)*(canvas->width  - 1) + 0.5;
-  int y = (fmod(v.y, 1.0) + 1.0)*(canvas->height - 1) + 0.5;
+  size_t x = llround((fmod(v.x, 1.0) + 1.0)*(canvas->width  - 1));
+  size_t y = llround((fmod(v.y, 1.0) + 1.0)*(canvas->height - 1));
   dmnsn_color c = dmnsn_get_pixel(canvas, x%canvas->width, y%canvas->height);
   return c;
 }
diff --git a/libdimension/dimension/color.h b/libdimension/dimension/color.h
index ecf7005..9664d22 100644
--- a/libdimension/dimension/color.h
+++ b/libdimension/dimension/color.h
@@ -81,6 +81,18 @@ dmnsn_color_is_black(dmnsn_color color)
          && fabs(color.trans) < dmnsn_epsilon;
 }
 
+/** Saturate the color components to [0.0, 1.0]. */
+DMNSN_INLINE dmnsn_color
+dmnsn_color_saturate(dmnsn_color color)
+{
+  color.R      = dmnsn_min(dmnsn_max(color.R,      0.0), 1.0);
+  color.G      = dmnsn_min(dmnsn_max(color.G,      0.0), 1.0);
+  color.B      = dmnsn_min(dmnsn_max(color.B,      0.0), 1.0);
+  color.trans  = dmnsn_min(dmnsn_max(color.trans,  0.0), 1.0);
+  color.filter = dmnsn_min(dmnsn_max(color.filter, 0.0), 1.0);
+  return color;
+}
+
 /* Perceptual color manipulation */
 
 /** Convert from sRGB space. */
diff --git a/libdimension/gl.c b/libdimension/gl.c
index be79094..a2825f9 100644
--- a/libdimension/gl.c
+++ b/libdimension/gl.c
@@ -37,12 +37,12 @@ dmnsn_gl_optimizer_fn(const dmnsn_canvas *canvas,
   dmnsn_color color = dmnsn_get_pixel(canvas, x, y);
   color = dmnsn_remove_filter(color);
   color = dmnsn_color_to_sRGB(color);
+  color = dmnsn_color_saturate(color);
 
-  /* Saturate R, G, and B to [0, UINT16_MAX] */
-  pixel[0] = dmnsn_min(dmnsn_max(color.R,     0.0), 1.0)*UINT16_MAX;
-  pixel[1] = dmnsn_min(dmnsn_max(color.G,     0.0), 1.0)*UINT16_MAX;
-  pixel[2] = dmnsn_min(dmnsn_max(color.B,     0.0), 1.0)*UINT16_MAX;
-  pixel[3] = dmnsn_min(dmnsn_max(color.trans, 0.0), 1.0)*UINT16_MAX;
+  pixel[0] = lround(color.R*UINT16_MAX);
+  pixel[1] = lround(color.G*UINT16_MAX);
+  pixel[2] = lround(color.B*UINT16_MAX);
+  pixel[3] = lround(color.trans*UINT16_MAX);
 }
 
 /* Optimize canvas for GL drawing */
@@ -97,12 +97,12 @@ dmnsn_gl_write_canvas(const dmnsn_canvas *canvas)
       color = dmnsn_get_pixel(canvas, x, y);
       color = dmnsn_remove_filter(color);
       color = dmnsn_color_to_sRGB(color);
+      color = dmnsn_color_saturate(color);
 
-      /* Saturate R, G, and B to [0, UINT16_MAX] */
-      pixel[0] = dmnsn_min(dmnsn_max(color.R,     0.0), 1.0)*UINT16_MAX;
-      pixel[1] = dmnsn_min(dmnsn_max(color.G,     0.0), 1.0)*UINT16_MAX;
-      pixel[2] = dmnsn_min(dmnsn_max(color.B,     0.0), 1.0)*UINT16_MAX;
-      pixel[3] = dmnsn_min(dmnsn_max(color.trans, 0.0), 1.0)*UINT16_MAX;
+      pixel[0] = lround(color.R*UINT16_MAX);
+      pixel[1] = lround(color.G*UINT16_MAX);
+      pixel[2] = lround(color.B*UINT16_MAX);
+      pixel[3] = lround(color.trans*UINT16_MAX);
     }
   }
 
diff --git a/libdimension/png.c b/libdimension/png.c
index 7f5da8f..21ad764 100644
--- a/libdimension/png.c
+++ b/libdimension/png.c
@@ -67,12 +67,12 @@ dmnsn_png_optimizer_fn(const dmnsn_canvas *canvas,
   color = dmnsn_get_pixel(canvas, x, y);
   color = dmnsn_remove_filter(color);
   color = dmnsn_color_to_sRGB(color);
+  color = dmnsn_color_saturate(color);
 
-  /* Saturate R, G, and B to [0, UINT16_MAX] */
-  pixel[0] = dmnsn_min(dmnsn_max(color.R,     0.0), 1.0)*UINT16_MAX;
-  pixel[1] = dmnsn_min(dmnsn_max(color.G,     0.0), 1.0)*UINT16_MAX;
-  pixel[2] = dmnsn_min(dmnsn_max(color.B,     0.0), 1.0)*UINT16_MAX;
-  pixel[3] = dmnsn_min(dmnsn_max(color.trans, 0.0), 1.0)*UINT16_MAX;
+  pixel[0] = lround(color.R*UINT16_MAX);
+  pixel[1] = lround(color.G*UINT16_MAX);
+  pixel[2] = lround(color.B*UINT16_MAX);
+  pixel[3] = lround(color.trans*UINT16_MAX);
 }
 
 /** Payload type for PNG write thread callback. */
@@ -241,13 +241,12 @@ dmnsn_png_write_canvas_thread(void *ptr)
       dmnsn_color color = dmnsn_get_pixel(payload->canvas, x, height - y - 1);
       color = dmnsn_remove_filter(color);
       color = dmnsn_color_to_sRGB(color);
+      color = dmnsn_color_saturate(color);
 
-      /* Saturate R, G, and B to [0, UINT16_MAX] */
-
-      row[4*x]     = dmnsn_min(dmnsn_max(color.R,     0.0), 1.0)*UINT16_MAX;
-      row[4*x + 1] = dmnsn_min(dmnsn_max(color.G,     0.0), 1.0)*UINT16_MAX;
-      row[4*x + 2] = dmnsn_min(dmnsn_max(color.B,     0.0), 1.0)*UINT16_MAX;
-      row[4*x + 3] = dmnsn_min(dmnsn_max(color.trans, 0.0), 1.0)*UINT16_MAX;
+      row[4*x]     = lround(color.R*UINT16_MAX);
+      row[4*x + 1] = lround(color.G*UINT16_MAX);
+      row[4*x + 2] = lround(color.B*UINT16_MAX);
+      row[4*x + 3] = lround(color.trans*UINT16_MAX);
     }
 
     /* Write the row */