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HLSL storing for the next step

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Hi, I am not sure to understand how shaders work. But I am in trouble to make a lot of effect. For exemple I have texture and I want that one becomes progressively blue. So I woud write something like that:

float4 texColor = texture.Sample(samLinear, psInput.Tex);
texture.Sample(samLinear, psInput.Tex).b += 0.1f;
return texColor;

Basicly my problem is to modify a texture and use at the next step the texture modified. I need it to do water effect, clouds effect and so... How can I do thiskind of effect? Any help will be apprecited, Thanks

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You cannot modify a texture you are reading from in a pixel shader. It seems that you are always adding a constant value to the texture pixel. In this case, you can upload a shader constant from your applicaiton. Your applicaiton can increase this constant over time. The code would look something like this.

// I assume you're using D3D10 due to your shader syntax...
// Main applicaiton init
D3DXVECTOR4 gColorIncrement(0.0f, 0.0f, 0.1f, 0.0f);
// During rendering.
gColorIncrement.b += 0.1f;
pEffectColorIncrementVariable->SetFloatVector( &g_ColorIncrement );
// Draw mesh...

float4 colorIncrement;
float4 main( PS_INPUT psInput )
float4 texColor = texture.Sample(samLinear, psInput.Tex);
return texColor + colorIncrement;


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Thanks for your reply,

Ok so there are no way to modify a texture from a shader, so to implement water effect

I see two solutions:
1- I have to give waterTextureArray[width*heigh] to the shader and use it in function of the Tex coordinate.
2- Create a texture and fill it directly, this method will not use shader.

I really have the feeling to miss something with the shader, I did light and fog effects.
I didn't manage to do bump mapping because noise function does't seem working. A bit desapointed with shader.

Anyway, I think the 1- is a better metod, isn't it?


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