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HLSL Pixel Shader returns (0,0,0,0)

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Started by sas_x86 May 08, 2012 03:13 PM

2 comments, last by NickUdell 11 years, 11 months ago

sas_x86

102

Author

May 08, 2012 03:13 PM

Hello.
There is a shader which implements shadow map technique

struct VS_INPUT { float4 Pos : POSITION0; float4 Normal: NORMAL; float4 Color : COLOR; float2 TexCoords : TEXCOORD0; float4 TexWeights : TEXCOORD1; };



float4x4 xLightWorld;

float4x4 xLightView;

float4x4 xLightProjection;



struct SMapVertexToPixel { float4 Position : POSITION0; float4 Position2D : POSITION1; };



SMapVertexToPixel ShadowMapVertexShader(VS_INPUT In)

{ SMapVertexToPixel Output = (SMapVertexToPixel)0;

Output.Position = mul(In.Pos, xLightWorld);

Output.Position = mul(Output.Position, xLightView);

Output.Position = mul(Output.Position, xLightProjection);

Output.Position2D = Output.Position; return Output; }



float4 ShadowMapPixelShader(SMapVertexToPixel PSIn) : COLOR

{

	 return float4(PSIn.Position2D.z/PSIn.Position2D.w, 0, 0, 1);

}

I run this code in PIX in Debugger window and for some pixel i have



ShadowMapPixelShader | ( 0.161, 0.000, 0.000, 1.000 ) | float4

but in Render window all pixels are black.
If i change code



float4 ShadowMapPixelShader(SMapVertexToPixel PSIn) : COLOR

{

	 return float4(0.5f, 0, 0, 1);

}

all pixels will be little bit red.
Why?

NickUdell

292

May 11, 2012 11:46 AM

Can you check in pix that your matrices are definitely being set?

May I also ask why Output.Position and Output.Position2D are identical? Seems a bit of a waste of space and resources...

Sole Creator of Pigment - a procedural, block-base space trading sim.

PhD student working on medical imaging at the University of Southampton.

Enjoyer of games, films, books and cider.

sas_x86

102

Author

May 15, 2012 03:13 PM

Can you check in pix that your matrices are definitely being set?

May I also ask why Output.Position and Output.Position2D are identical? Seems a bit of a waste of space and resources...

Hello.
My matrices are set. I can see it in Mesh window of Pix (Pre-vertex shader, Post-Vertex shader and Viewport is correct).
Output.Position and Output.Position2D are identical because i thought that after vertex shader i can't use a Position field in the Pixel Shader.

NickUdell

292

May 15, 2012 05:51 PM

You can use the position value in the pixel shader, it'll be interpolated between the vertices so it will be the position at that pixel.

Looks to me like you're outputting depth at that point. What are you near and far plane values? If you have a really large range then the object might appear with a very dark colour due to how far away it is. Could you set it to return 1 - depth to make sure it's definitely setting the pixel colour there?

Sole Creator of Pigment - a procedural, block-base space trading sim.

PhD student working on medical imaging at the University of Southampton.

Enjoyer of games, films, books and cider.

HLSL Pixel Shader returns (0,0,0,0)

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