Eevee: internal support for arbitrary number of volume grids

This has no user visible impact yet since smoke volumes only support a fixed
set of attributes, but will become important with the new volume object.

For GPU shader compilation, volume grids are now handled separately from
image textures. They are somewhere between a vertex attribute and an image
texture, basically an attribute that is stored as a texture.

Differential Revision: https://developer.blender.org/D6952

1 files changed, 21 insertions, 57 deletions

diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
index 0fecb5bd1f9..a80cd3cb329 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_volume_info.glsl
@@ -1,18 +1,21 @@
-void node_attribute_volume_density(sampler3D tex, out vec4 outcol, out vec3 outvec, out float outf)
+
+/* Uniforms to convert smoke grid values into standard range. */
+uniform vec3 volumeColor = vec3(1.0);
+uniform vec2 volumeTemperature = vec2(0.0);
+
+/* Generic volume attribute. */
+void node_attribute_volume(sampler3D tex, out vec3 outvec)
 {
 #if defined(MESH_SHADER) && defined(VOLUMETRICS)
   vec3 cos = volumeObjectLocalCoord;
 #else
   vec3 cos = vec3(0.0);
 #endif
-  outf = texture(tex, cos).r;
-  outvec = vec3(outf, outf, outf);
-  outcol = vec4(outf, outf, outf, 1.0);
+  outvec = texture(tex, cos).rgb;
 }
 
-uniform vec3 volumeColor = vec3(1.0);
-
-void node_attribute_volume_color(sampler3D tex, out vec4 outcol, out vec3 outvec, out float outf)
+/* Special color attribute for smoke. */
+void node_attribute_volume_color(sampler3D tex, out vec3 outvec)
 {
 #if defined(MESH_SHADER) && defined(VOLUMETRICS)
   vec3 cos = volumeObjectLocalCoord;
@@ -20,70 +23,31 @@ void node_attribute_volume_color(sampler3D tex, out vec4 outcol, out vec3 outvec
   vec3 cos = vec3(0.0);
 #endif
 
-  vec4 value = texture(tex, cos).rgba;
   /* Density is premultiplied for interpolation, divide it out here. */
+  vec4 value = texture(tex, cos).rgba;
   if (value.a > 1e-8) {
     value.rgb /= value.a;
   }
 
   outvec = value.rgb * volumeColor;
-  outcol = vec4(outvec, 1.0);
-  outf = avg(outvec);
-}
-
-void node_attribute_volume_flame(sampler3D tex, out vec4 outcol, out vec3 outvec, out float outf)
-{
-#if defined(MESH_SHADER) && defined(VOLUMETRICS)
-  vec3 cos = volumeObjectLocalCoord;
-#else
-  vec3 cos = vec3(0.0);
-#endif
-  outf = texture(tex, cos).r;
-  outvec = vec3(outf, outf, outf);
-  outcol = vec4(outf, outf, outf, 1.0);
 }
 
-void node_attribute_volume_temperature(
-    sampler3D tex, vec2 temperature, out vec4 outcol, out vec3 outvec, out float outf)
+/* Special temperature attribute for smoke. */
+void node_attribute_volume_temperature(sampler3D tex, out float outf)
 {
 #if defined(MESH_SHADER) && defined(VOLUMETRICS)
   vec3 cos = volumeObjectLocalCoord;
 #else
   vec3 cos = vec3(0.0);
 #endif
-  float flame = texture(tex, cos).r;
-
-  outf = (flame > 0.01) ? temperature.x + flame * (temperature.y - temperature.x) : 0.0;
-  outvec = vec3(outf, outf, outf);
-  outcol = vec4(outf, outf, outf, 1.0);
-}
 
-void node_volume_info(sampler3D densitySampler,
-                      sampler3D colorSampler,
-                      sampler3D flameSampler,
-                      vec2 temperature,
-                      out vec4 outColor,
-                      out float outDensity,
-                      out float outFlame,
-                      out float outTemprature)
-{
-#if defined(MESH_SHADER) && defined(VOLUMETRICS)
-  vec3 p = volumeObjectLocalCoord;
-#else
-  vec3 p = vec3(0.0);
-#endif
-
-  outDensity = texture(densitySampler, p).r;
-
-  /* Color is premultiplied for interpolation, divide it out here. */
-  vec4 color = texture(colorSampler, p);
-  if (color.a > 1e-8) {
-    color.rgb /= color.a;
+  float value = texture(tex, cos).r;
+  if (volumeTemperature.x < volumeTemperature.y) {
+    outf = (value > 0.01) ?
+               volumeTemperature.x + value * (volumeTemperature.y - volumeTemperature.x) :
+               0.0;
+  }
+  else {
+    outf = value;
   }
-  outColor = vec4(color.rgb * volumeColor, 1.0);
-
-  float flame = texture(flameSampler, p).r;
-  outFlame = flame;
-
-  outTemprature = (flame > 0.01) ? temperature.x + flame * (temperature.y - temperature.x) : 0.0;
 }