Eevee: Add Velocity pass.

This pass create a velocity buffer which is basically a 2D motion vector
texture. This is not yet used for rendering but will be usefull for motion
blur and temporal reprojection.

1 files changed, 19 insertions, 0 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/effect_velocity_resolve_frag.glsl b/source/blender/draw/engines/eevee/shaders/effect_velocity_resolve_frag.glsl
new file mode 100644
index 00000000000..9c118277212
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/effect_velocity_resolve_frag.glsl
@@ -0,0 +1,19 @@
+
+uniform mat4 currPersinv;
+uniform mat4 pastPersmat;
+
+out vec2 outData;
+
+void main()
+{
+	/* Extract pixel motion vector from camera movement. */
+	ivec2 texel = ivec2(gl_FragCoord.xy);
+	vec2 uv = gl_FragCoord.xy / vec2(textureSize(depthBuffer, 0).xy);
+
+	float depth = texelFetch(depthBuffer, texel, 0).r;
+
+	vec3 world_position = project_point(currPersinv, vec3(uv, depth) * 2.0 - 1.0);
+	vec2 uv_history = project_point(pastPersmat, world_position).xy * 0.5 + 0.5;
+
+	outData = uv - uv_history;
+}