Fixed border extension for the sunbeams node.

This ensures that the beams color does not darken along borders,
by using the last valid color of the ray as the border color (extending
colors in the direction of the source point).

1 files changed, 17 insertions, 10 deletions

diff --git a/source/blender/compositor/operations/COM_SunBeamsOperation.cpp b/source/blender/compositor/operations/COM_SunBeamsOperation.cpp
index 5caaff7d975..bcef652a8b5 100644
--- a/source/blender/compositor/operations/COM_SunBeamsOperation.cpp
+++ b/source/blender/compositor/operations/COM_SunBeamsOperation.cpp
@@ -138,6 +138,7 @@ struct BufferLineAccumulator {
 		int x, y, num;
 		float v, dv;
 		float falloff_factor;
+		float border[4];
 
 		if ((int)pt_ofs[0] == 0 && (int)pt_ofs[1] == 0) {
 			copy_v4_v4(output, input->getBuffer() + COM_NUMBER_OF_CHANNELS * ((int)source[0] + input->getWidth() * (int)source[1]));
@@ -146,19 +147,26 @@ struct BufferLineAccumulator {
 
 		/* initialise the iteration variables */
 		float *buffer = init_buffer_iterator(input, source, pt_ofs, dist_min, dist_max, x, y, num, v, dv, falloff_factor);
-
-		int tot = 0;
+		zero_v3(border);
+		border[3] = 1.0f;
 
 		/* v_local keeps track of when to decrement v (see below) */
 		float v_local = v - floorf(v);
 
 		for (int i = 0; i < num; i++) {
-			/* range check, abort when running beyond the image border */
-			if (x < rect.xmin || x >= rect.xmax || y < rect.ymin || y >= rect.ymax)
-				break;
-
-			float f = 1.0f - (float)i * falloff_factor;
-			madd_v4_v4fl(output, buffer, buffer[3] * f * f);
+			float weight = 1.0f - (float)i * falloff_factor;
+			weight *= weight;
+			
+			/* range check, use last valid color when running beyond the image border */
+			if (x >= rect.xmin && x < rect.xmax && y >= rect.ymin && y < rect.ymax) {
+				madd_v4_v4fl(output, buffer, buffer[3] * weight);
+				/* use as border color in case subsequent pixels are out of bounds */
+				copy_v4_v4(border, buffer);
+			}
+			else {
+				madd_v4_v4fl(output, border, border[3] * weight);
+			}
+			
 			/* TODO implement proper filtering here, see
 			 * http://en.wikipedia.org/wiki/Lanczos_resampling
 			 * http://en.wikipedia.org/wiki/Sinc_function
@@ -166,9 +174,8 @@ struct BufferLineAccumulator {
 			 * using lanczos with x = distance from the line segment,
 			 * normalized to a == 0.5f, could give a good result
 			 *
-			 * for now just count samples and divide equally at the end ...
+			 * for now just divide equally at the end ...
 			 */
-			tot++;
 
 			/* decrement u */
 			x -= fxx;