I'm trying to implement GPU based geometry clipmapping and have problems to apply a simple heightmap to my terrain. For the heightmap I use a simple texture with the surface format "single". I've taken the texture from here. To apply it to my terrain, I use the following shader code:
texture Heightmap;
sampler2D HeightmapSampler = sampler_state {
Texture = <Heightmap>;
MinFilter = Point;
MagFilter = Point;
MipFilter = Point;
AddressU = Mirror;
AddressV = Mirror;
};
Vertex Shader:
float4 worldPos = mul(float4(pos.x,0.0f,pos.y, 1.0f), worldMatrix);
float elevation = tex2Dlod(HeightmapSampler, float4(worldPos.x, worldPos.z,0,0));
worldPos.y = elevation * 128;
The complete vertex shader (also containig clipmapping transforms) looks like this:
float4x4 View : View;
float4x4 Projection : Projection;
float3 CameraPos : CameraPosition;
float LODscale; //The LOD ring index 0:highest x:lowest
float2 Position; //The position of the part in the world
texture Heightmap;
sampler2D HeightmapSampler = sampler_state {
Texture = <Heightmap>;
MinFilter = Point;
MagFilter = Point;
MipFilter = Point;
AddressU = Mirror;
AddressV = Mirror;
};
//Accept only float2 because we extract 3rd dim out of Heightmap
float4 wireframe_VS(float2 pos : POSITION) : POSITION{
float4x4 worldMatrix = float4x4(
LODscale, 0, 0, 0,
0, LODscale, 0, 0,
0, 0, LODscale, 0,
- Position.x * 64 * LODscale + CameraPos.x, 0, Position.y * 64 * LODscale + CameraPos.z, 1);
float4 worldPos = mul(float4(pos.x,0.0f,pos.y, 1.0f), worldMatrix);
float elevation = tex2Dlod(HeightmapSampler, float4(worldPos.x, worldPos.z,0,0));
worldPos.y = elevation * 128;
float4 viewPos = mul(worldPos, View);
float4 projPos = mul(viewPos, Projection);
return projPos;
}
