XNA/HLSL Heightmap from VertexShader - xna

Question

Anyone can tell why i get this Error:
The current vertex declaration does not include all the elements required by the current vertex shader. TextureCoordinate0 is missing.
With the standard Vertex Shader, everything is fine.
Here is my Shader File:
float4x4 World;
float4x4 View;
float4x4 Projection;
float4 color;
float seaLevel;
texture myTexture;
float maxHeight = 128;
float height;
sampler2D mySampler = sampler_state
{
Texture = <myTexture>;
MinFilter = Point;
MagFilter = Point;
MipFilter = Point;
AddressU = Clamp;
AddressV = Clamp;
};
struct VertexShaderInput
{
float4 Position : POSITION0;
};
struct VertexShaderOutput
{
float4 Position : POSITION0;
};
struct VS_INPUT
{
float4 position : POSITION;
float4 uv : TEXCOORD0;
};
struct VS_OUTPUT
{
float4 position : POSITION;
float4 uv : TEXCOORD0;
float4 worldPos : TEXCOORD1;
};
VS_OUTPUT Transform(VS_INPUT In)
{
VS_OUTPUT Out = (VS_OUTPUT)0;
float4x4 viewProj = mul(View, Projection);
float4x4 worldViewProj= mul(World, viewProj);
float height = tex2Dlod ( mySampler, float4(In.uv.xy , 0 , 0 ) );
In.position.y = height * maxHeight;
Out.worldPos = mul(In.position, World);
Out.position = mul( In.position , worldViewProj);
Out.uv = In.uv;
return Out;
}
VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
VertexShaderOutput output;
float4 worldPosition = mul(input.Position, World);
worldPosition = float4(normalize(worldPosition.xyz) * seaLevel, 1);
float4 viewPosition = mul(worldPosition, View);
output.Position = mul(viewPosition, Projection);
return output;
}
float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0
{
return color;
}
technique Technique1
{
pass Pass1
{
VertexShader = compile vs_3_0 Transform();
PixelShader = compile ps_3_0 PixelShaderFunction();
}
}

Answer 1

The model that your are trying to draw has vertex that no contains texture coordinates.
Your vertex shader needs a texture coordinate to work, as seen in the struct that is used by the vertex shader specified in your technique.
struct VS_INPUT
{
float4 position : POSITION;
float4 uv : TEXCOORD0;
};
technique Technique1
{
pass Pass1
{
VertexShader = compile vs_3_0 Transform();
So, you have two choices:
1) Remove "uv" from VS_INPUT
2) Add the texture coordiante field to the vertex used by your model.

Answer 2

I solved same problem by opening the model in 3D Studio Max, adding "UVM Map" modifier and exporting back. Not a satisfying solution but worked for me.