Viewport smoke: add support to render the volume using a color ramp.

This is yet another debug option that allows to render an arbitrary
simulation field by using a color ramp to inspect its voxel values.
Note that when using this, fire rendering is turned off.

Reviewers: plasmasolutions, gottfried

Differential Revision: https://developer.blender.org/D1733

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/gpu/shaders/gpu_shader_smoke_frag.glsl b/source/blender/gpu/shaders/gpu_shader_smoke_frag.glsl
index fd790009e02..6ded453225e 100644
--- a/source/blender/gpu/shaders/gpu_shader_smoke_frag.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_smoke_frag.glsl
@@ -8,10 +8,17 @@ uniform float density_scale;
 uniform sampler3D soot_texture;
 uniform sampler3D shadow_texture;
 
+#ifdef USE_COBA
+uniform sampler1D transfer_texture;
+uniform sampler3D color_band_texture;
+#endif
+
 void main()
 {
 	/* compute color and density from volume texture */
 	vec4 soot = texture3D(soot_texture, coords);
+
+#ifndef USE_COBA
 	vec3 soot_color;
 	if (soot.a != 0) {
 		soot_color = active_color * soot.rgb / soot.a;
@@ -31,6 +38,11 @@ void main()
 
 	/* premultiply alpha */
 	vec4 color = vec4(soot_alpha * soot_color, soot_alpha);
+#else
+	float color_band = texture3D(color_band_texture, coords).r;
+	vec4 transfer_function = texture1D(transfer_texture, color_band);
+	vec4 color = transfer_function * density_scale;
+#endif
 
 	gl_FragColor = color;
 }