Eevee: Add support for new Hair geometry system.

This now can shade actual poly strips that mimics cylinders.
This makes hair coverage exact compared to the line method and result in
smoother fading hair.

This does make the sampling a bit more exact but needs more samples to
converge properly.

1 files changed, 16 insertions, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/prepass_vert.glsl b/source/blender/draw/engines/eevee/shaders/prepass_vert.glsl
index c756e061d70..1ed4f5f6500 100644
--- a/source/blender/draw/engines/eevee/shaders/prepass_vert.glsl
+++ b/source/blender/draw/engines/eevee/shaders/prepass_vert.glsl
@@ -7,13 +7,28 @@ layout(std140) uniform clip_block {
 	vec4 ClipPlanes[1];
 };
 
+#ifndef HAIR_SHADER
 in vec3 pos;
+#endif
 
 void main()
 {
+#ifdef HAIR_SHADER
+	float time, thick_time, thickness;
+	vec3 pos, nor, binor;
+	hair_get_pos_tan_nor_time(
+	        (ProjectionMatrix[3][3] == 0.0),
+	        ViewMatrixInverse[3].xyz, ViewMatrixInverse[2].xyz,
+	        pos, nor, binor, time, thickness, thick_time);
+
+	gl_Position = ViewProjectionMatrix * vec4(pos, 1.0);
+	vec4 worldPosition = vec4(pos, 1.0);
+#else
 	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
-#ifdef CLIP_PLANES
 	vec4 worldPosition = (ModelMatrix * vec4(pos, 1.0));
+#endif
+
+#ifdef CLIP_PLANES
 	gl_ClipDistance[0] = dot(vec4(worldPosition.xyz, 1.0), ClipPlanes[0]);
 #endif
 	/* TODO motion vectors */