Clay Engine: Convert Lamp to use new instancing feature.

source/blender/gpu/shaders/gpu_shader_3D_lamp_vert.glsl

@@ -5,9 +5,10 @@ uniform float size;
 uniform float pixel_size;
 
 in vec2 pos;
-in mat4 InstanceModelMatrix;
+in vec3 lamp_pos;
+in vec3 color;
 
-#define lamp_pos InstanceModelMatrix[3].xyz
+flat out vec4 finalColor;
 
 float mul_project_m4_v3_zfac(in vec3 co)
 {
@@ -21,4 +22,5 @@ void main()
 	float pix_size = mul_project_m4_v3_zfac(lamp_pos) * pixel_size;
 	vec3 screen_pos = screen_vecs[0].xyz * pos.x + screen_vecs[1].xyz * pos.y;
 	gl_Position = ViewProjectionMatrix * vec4(lamp_pos + screen_pos * size * pix_size, 1.0);
+	finalColor = vec4(color, 1.0);
 }