So I am creating a geometry map using a pixel shader. I iterate over the texture coordinates using the pixel shader and calculate noise, then output this final noise value. This is for a chunked lod planet system. The noise works fine with the first patch, however when you zoom in and it tries to generate a new heightmap, ALL texture coordinates x and y in the pixel shader are the same.

My main question is what would cause all the pixel shader texture coordinates to be the same for every pixel when it runs this a second time. The vertices and texture coordinates never change, so I don't understand why the pixel shader doesn't return the same values.

Here is the code.I am using c# and XNA.


[color=#526569][font=Verdana, Arial, Helvetica, sans-serif]

[background=rgb(244, 247, 245)]SHADER:[/background]

[/font]

[color=#526569][font=Verdana, Arial, Helvetica, sans-serif]

float4 PS_INoise(float2 inTexCoords : TEXCOORD0) : COLOR0
{
float land0 = (float)0;

// Get the direction, from the origin (top-left) to the end vector (bottom-right)
float3 xDirection = xNE - xNW;
float3 zDirection = xSW - xNW;

// Scale the distance by the texture coordinate (which is between 0 and 1)
xDirection *= inTexCoords.x;
zDirection *= 1 - inTexCoords.y;

// Lerp outward from the originSY (top-left) in the direction of the end vector (bottom-right)
float3 lerpedWorldPos = xNW + xDirection + zDirection;
land0 = inoise(lerpedWorldPos);
land0 = inTexCoords.y;

return land0;
}




APPLICATION:

[/font]

//pre-transformed quad
m_Vertices[0] = new VertexPositionTexture(new Vector3(-1, 1, 0f), new Vector2(0, 1));
m_Vertices[1] = new VertexPositionTexture(new Vector3(1, 1, 0f), new Vector2(1 , 1));
m_Vertices[2] = new VertexPositionTexture(new Vector3(-1, -1, 0f), new Vector2(0, 0));
m_Vertices[3] = new VertexPositionTexture(new Vector3(1, -1, 0f), new Vector2(1 , 0 ));


perlinCombined.Parameters["xNW"].SetValue(new Vector3(-1, 1, 0f));
perlinCombined.Parameters["xNE"].SetValue(new Vector3(1, 1, 0f));
perlinCombined.Parameters["xSW"].SetValue(new Vector3(-1, -1, 0f));
perlinCombined.Parameters["xSE"].SetValue(new Vector3(1, -1, 0f));



CRenderManager.Singleton.GetGD().SetRenderTarget(RenderTarget);
CRenderManager.Singleton.GetGD().BlendState = BlendState.Opaque;
foreach (EffectPass pass in perlinCombined.CurrentTechnique.Passes)
{
pass.Apply();
CRenderManager.Singleton.GetGD().DrawUserPrimitives(PrimitiveType.TriangleStrip, m_Vertices, 0,2);
}

CRenderManager.Singleton.GetGD().SetRenderTarget(null);

I have still been unable to fix this. Forgot to add also, anytime I zoom int o the planet and it starts creating children and calling the pixel shader more, the ENTIRE SCREEN is purple, like the clearing color switched somehow. It goes way when I disable setting a render target.
Any help would be appreciated. Thanks.

Somewhat solved. For some reason, by setting the RasterizationState(), it is making all future pixel shader calls not iterate.



RasterizerState rs = new RasterizerState();

rs.FillMode = FillMode.WireFrame;
rs.CullMode = CullMode.CullClockwiseFace;
GraphicsDevice.RasterizerState = rs;