source: data/Media/materials/programs/Grass.cg @ 5161

// Vertex program to wave some grass about
// Simplistic, assumes base of the grass at 0
void grass_vp(float4 position : POSITION,
                          float3 normal   : NORMAL,
                          float2 uv               : TEXCOORD0,
                          out float4 oPosition : POSITION,
                          out float2 oUv           : TEXCOORD0,
                          out float4 colour    : COLOR,

                          uniform float4x4 worldViewProj,
                          uniform float4 ambient,
                          uniform float4 objSpaceLight,
                          uniform float4 lightColour,
                          uniform float4 offset)
{
        float4 mypos = position;
        //offset = float4(0.5, 0, 0, 0);
        float4 factor = float4(1,1,1,1) - uv.yyyy;
        mypos = mypos + offset * factor;
        oPosition = mul(worldViewProj, mypos);

        oUv = uv;
        // get vertex light direction (support directional and point)
        float3 light = normalize(
                objSpaceLight.xyz -  (position.xyz * objSpaceLight.w));
        float diffuseFactor = max(dot(normal, light), 0);
        
        
        colour = ambient + diffuseFactor * lightColour;
}