HLSL Shader Question : Vertex Shader fails, Pixel Shader Succeeds

Graphics and GPU Programming Programming

Started by sriam September 04, 2011 04:40 AM

6 comments, last by L. Spiro 12 years, 7 months ago

sriam

100

Author

September 04, 2011 04:40 AM

Here is my sooper awesomer shader:





// globals, set via constant table

uniform extern float4x4	MatWorld;

 sampler2D		TexSampler;



// Vertex shader input structure

// using a 2d engine so Position is float3

struct VS_INPUT

{

    float4 Position   : POSITION;

    float2 Texture    : TEXCOORD0;

};



// Vertex shader output structure

// Position converted to float4 for DX

struct VS_OUTPUT

{

    float4 Position   : POSITION;

    float2 Texture    : TEXCOORD0;

};



// **** VERTEX SHADER ****

 VS_OUTPUT vs_main( in VS_INPUT In )

{

    VS_OUTPUT Out = (VS_OUTPUT)0;



    Out.Position = In.Position;

    Out.Texture  = In.Texture;          //copy original texcoords



    return Out;                        

}



// **** PIXEL SHADER ****

 float4 ps_main( float2 Tex : TEXCOORD0 ) : COLOR0

{

    float4 Color;



    Color = tex2D( TexSampler, Tex.xy);

    return Color;

}



technique fx_technique 

{

	pass P0

	{

		VertexShader	= compile vs_2_0 vs_main();

		PixelShader		= compile ps_2_0 ps_main();



		FillMode = Solid;

	}

}

It takes any textured quad I give it and renders NOTHING! w00t!

BUT! If I change the technique to:







technique fx_technique 

{

	pass P0

	{

		VertexShader	= null;

		PixelShader		= compile ps_2_0 ps_main();



		FillMode = Solid;

	}

}

It renders my textures. I've debugged the Shader with Pix and it says the the VertexShader is doing what it's supposed to, but it doesn't draw anything and I think for some reason that when vs_main() is called ps_main() isn't.

Any clues are greatly appreciated.

smasherprog

570

September 04, 2011 05:30 AM

You are missing position in your pixel shader. Your vertex shader outputs position and texcoords, but the pixel shader only takes a texcoord. Add Position and it should compile

Wisdom is knowing when to shut up, so try it.
--Game Development http://nolimitsdesigns.com: Reliable UDP library, Threading library, Math Library, UI Library. Take a look, its all free.

kauna

2,925

September 04, 2011 08:06 AM

I have found it a good practice to use the vertex output structure as input to the pixel shader.

[color=#1C2837][font=CourierNew, monospace][size=2][color=#000000] float4 ps_main[color=#666600]([color=#000000] [/font][font=CourierNew, monospace][size=2]VS_OUTPUT[/font][font=CourierNew, monospace][size=2][color=#000000] [color="#660066"]V[color=#000000] [color=#666600])[color=#000000] [color=#666600]:[color=#000000] COLOR0[/font]
[font=CourierNew, monospace][size=2][color=#000000]
[/font]
[color=#000000]Cheers!

sriam

100

Author

September 04, 2011 09:22 AM

same thing...

Here it is now:





// globals, set via constant table

uniform extern float4x4	MatWorld;

sampler2D		TexSampler;



struct VS_VERTEX

{

    float4 Position   : POSITION;

    float2 Texture    : TEXCOORD0;

};



// **** VERTEX SHADER ****

VS_VERTEX vs_main( VS_VERTEX vsIn )

{

    VS_VERTEX Out = (VS_VERTEX)0;



	//float4x4 mat = mul(MatProj, MatView);

	//mat = mul(MatWorld, mat);



	Out.Position = mul(vsIn.Position, MatWorld);

    Out.Texture  = vsIn.Texture;  



    return Out;                        

}



// **** PIXEL SHADER ****

float4 ps_main( VS_VERTEX vsIn ) : COLOR0

{

    float4 Color;



    Color = tex2D( TexSampler, vsIn.Texture.xy);

    return Color;

}



technique fx_technique 

{

	pass P0

	{

		VertexShader	= compile vs_2_0 vs_main();

		PixelShader		= compile ps_2_0 ps_main();

		FillMode = Solid;

	}

}

If I set VertexShader = null; in the technique it renders, but no transform.

If I debug the Vertex Shader in Pix, it gives me the correct values, but nothing is drawn.

sriam

100

Author

September 04, 2011 09:40 AM

I have a better idea!

I think DX moves the vertices into 3d space differently when you translate in C++ using d3d_device->SetTransform() (which works) then if you translate using a shader.

I'll go back and make sure the ViewPort and Camera are set for 3d.

Thanks for your help.

L. Spiro

25,818

September 04, 2011 09:44 AM

If the names of your variables are not misleading, you are transforming the vertex by the world matrix.
You must translate it by the world-view-projection matrix.

L. Spiro

I restore Nintendo 64 video-game OST’s into HD! https://www.youtube.com/channel/UCCtX_wedtZ5BoyQBXEhnVZw/playlists?view=1&sort=lad&flow=grid

raicuandi

113

September 04, 2011 11:41 AM

Multiply by world, then by view, then by projection.

L. Spiro

25,818

September 04, 2011 12:11 PM

But to be clear, These matrices can easily be combined into one, so that you do not waste cycles by performing 3 matrix multiplies.
It is best to compose a single matrix that represents all three of these transforms, and call it the WorldViewProjection matrix.

L. Spiro

I restore Nintendo 64 video-game OST’s into HD! https://www.youtube.com/channel/UCCtX_wedtZ5BoyQBXEhnVZw/playlists?view=1&sort=lad&flow=grid

HLSL Shader Question : Vertex Shader fails, Pixel Shader Succeeds

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