Eevee: Volumetrics: Add Volume object support.

This is quite basic as it only support boundbing boxes.
But the material can refine the volume shape in anyway the user like.

To overcome this limitation, a voxelisation should be done on the mesh (generating a SDF maybe?) and tested against every volumetric cell.

1 files changed, 29 insertions, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
index a3e2979a9b4..00e01e753f9 100644
--- a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
@@ -7,12 +7,21 @@
 uniform ivec3 volumeTextureSize;
 uniform vec3 volume_jitter;
 
+#ifdef MESH_SHADER
+uniform mat4 volumeObjectMatrix;
+uniform vec3 volumeOrcoLoc;
+uniform vec3 volumeOrcoSize;
+#endif
+
 flat in int slice;
 
 /* Warning: theses are not attributes, theses are global vars. */
 vec3 worldPosition = vec3(0.0);
 vec3 viewPosition = vec3(0.0);
 vec3 viewNormal = vec3(0.0);
+#ifdef MESH_SHADER
+vec3 volumeObjectLocalCoord = vec3(0.0);
+#endif
 
 layout(location = 0) out vec4 volumeScattering;
 layout(location = 1) out vec4 volumeExtinction;
@@ -28,11 +37,30 @@ void main()
 
 	viewPosition = get_view_space_from_depth(ndc_cell.xy, ndc_cell.z);
 	worldPosition = transform_point(ViewMatrixInverse, viewPosition);
+#ifdef MESH_SHADER
+	volumeObjectLocalCoord = transform_point(volumeObjectMatrix, worldPosition);
+	volumeObjectLocalCoord = (volumeObjectLocalCoord - volumeOrcoLoc + volumeOrcoSize) / (volumeOrcoSize * 2.0);
+
+	if (any(lessThan(volumeObjectLocalCoord, vec3(0.0))) ||
+	    any(greaterThan(volumeObjectLocalCoord, vec3(1.0))))
+	    discard;
+#endif
 
+#ifdef CLEAR
+	Closure cl = CLOSURE_DEFAULT;
+#else
 	Closure cl = nodetree_exec();
+#endif
 
 	volumeScattering = vec4(cl.scatter, 1.0);
 	volumeExtinction = vec4(max(vec3(1e-4), cl.absorption + cl.scatter), 1.0);
 	volumeEmissive = vec4(cl.emission, 1.0);
-	volumePhase = vec4(cl.anisotropy, vec3(1.0));
+
+	/* Do not add phase weight if no scattering. */
+	if (all(equal(cl.scatter, vec3(0.0)))) {
+		volumePhase = vec4(0.0);
+	}
+	else {
+		volumePhase = vec4(cl.anisotropy, vec3(1.0));
+	}
 }