Hi,

I have seen a nice shader code, that makes the render to look
like a pencil drawing, but i dont understand it.
I got the OpenGL code for it on an article in Programings Gems 4.
its like this,
Code:

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//stage 0: smooth threshold function 4*((1-L)-H)

glActiveTexture( GL_TEXTURE0 );
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE );
glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_SUBTRACT );
glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS );
glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE );
glTexEnvi( GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_ONE_MINUS_SRC_COLOR );
glTexEnvi( GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR );
glTexEnvi(GL_TEXTURE_ENV,

//stage 1: invert function (1-previous)
glActiveTexture( GL_TEXTURE1 );
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE );
glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE );
glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS );
glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_ONE_MINUS_SRC_COLOR );

---

can anyone help me to convert it to A6 and explain me it a bit?
THANKS!!!!

im not sure its a shader or there is some other way
(as multitexture operations)to make this effect.

That's not a shader, rather just normal OpenGL code. Though you can probably achieve the thing that code does with a shader too... I'm not familiar with HLSL (which A6 uses), just with GLSL so probably won't be able to help you...

There is a sketch shader on the wiki if I'm not mistaken.

If there isn't, let me know and I can take a lil' look for it under some of the other users i know. Or, you can do a search on the forums for it, but I know it's somewhere...

Yes this is not a shader but Opengl code using register combiners i beleive... i'm not very familiar with OGL but you might be able to map this to D3D Fixed-Function commands.

However, for such effects you are normally encouraged to use pixel shaders...