[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [16714] branches/sim_physics/source/ blender/render/intern/source/volumetric.c: * Moved the sample location for shading to the middle of the volumetric step .

[Matt Ebb]

Revision: 16714
          http://projects.blender.org/plugins/scmsvn/viewcvs.php?view=rev&root=bf-blender&revision=16714
Author:   broken
Date:     2008-09-24 09:49:24 +0200 (Wed, 24 Sep 2008)

Log Message:
-----------
* Moved the sample location for shading to the middle of the volumetric step. This fixes a nagging bug that would cause noise/odd moire-ish patterns, due to raytrace numerical errors:

http://mke3.net/blender/devel/rendering/volumetrics/vol_clouds_moire.jpg

Modified Paths:
--------------
    branches/sim_physics/source/blender/render/intern/source/volumetric.c

Modified: branches/sim_physics/source/blender/render/intern/source/volumetric.c
===================================================================
--- branches/sim_physics/source/blender/render/intern/source/volumetric.c	2008-09-24 07:38:12 UTC (rev 16713)
+++ branches/sim_physics/source/blender/render/intern/source/volumetric.c	2008-09-24 07:49:24 UTC (rev 16714)
@@ -401,7 +401,7 @@
 	float vec[3], stepvec[3] = {0.0, 0.0, 0.0};
 	float tau[3], step_emit[3], step_scatter[3] = {0.0, 0.0, 0.0};
 	int s;
-	float step_sta[3], step_end[3];
+	float step_sta[3], step_end[3], step_mid[3];
 	float col_behind[3];
 	float total_density = 0.f;
 	
@@ -433,6 +433,9 @@
 		/* there's only any point shading here
 		 * if there's actually some density to shade! */
 		if (density > 0.01f) {
+			step_mid[0] = step_sta[0] + (stepvec[0] * 0.5);
+			step_mid[1] = step_sta[1] + (stepvec[1] * 0.5);
+			step_mid[2] = step_sta[2] + (stepvec[2] * 0.5);
 		
 			/* transmittance component (alpha) */
 			vol_get_attenuation(shi, tau, step_sta, step_end, density, stepsize);
@@ -444,8 +447,8 @@
 			//if (rgb_to_luminance(tr[0], tr[1], tr[2]) < 1e-3) break;
 			
 			/* incoming light via emission or scattering (additive) */
-			vol_get_emission(shi, step_emit, step_sta, density);
-			vol_get_scattering(shi, step_scatter, step_end, stepsize, density);
+			vol_get_emission(shi, step_emit, step_mid, density);
+			vol_get_scattering(shi, step_scatter, step_mid, stepsize, density);
 			
 			VecAddf(d_radiance, step_emit, step_scatter);