How to get a CG vertex and pixel shader to work together?

102

Author

July 29, 2008 08:17 PM

I can't seem to figure out how to make a CG vertex and pixel shader work together. I create the shaders like this:


cgContext = cgCreateContext();
cg_vs = cgCreateProgramFromFile(cgContext, CG_SOURCE, "Data/Shaders/default.cg", cgGLGetLatestProfile(CG_GL_VERTEX), "VS", 0);
cgGLLoadProgram(cg_vs);
cg_ps = cgCreateProgramFromFile(cgContext, CG_SOURCE, "Data/Shaders/default.cg", cgGLGetLatestProfile(CG_GL_FRAGMENT), "PS", 0);
cgGLLoadProgram(cg_ps);
position		= cgGetNamedParameter(cg_vs, "IN.position");
color			= cgGetNamedParameter(cg_vs, "IN.color");
modelViewMatrix	= cgGetNamedParameter(cg_vs, "ModelViewProj");

Then I render them like this:


void render()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt(0.0f, 25.0f, -45.0f, 0.0f, 0.0f, 0.0f, 0, 1, 0);
cgGLSetStateMatrixParameter(modelViewMatrix, CG_GL_MODELVIEW_PROJECTION_MATRIX, CG_GL_MATRIX_IDENTITY);
cgGLBindProgram(cg_vs);
cgGLBindProgram(cg_ps);
cgGLSetParameter4f(color, 0.5f, 1.0f, 0.5f, 1.0f);
	glTranslatef(0.0f,0.0f,0.0f);
	glBegin(GL_TRIANGLES);
		glVertex3f( 0.0f, 1.0f, 0.0f);
		glVertex3f(-1.0f,-1.0f, 0.0f);
		glVertex3f( 1.0f,-1.0f, 0.0f);
	glEnd();	
SwapBuffers(hDC);
}

I have no idea what I need to do to make them work together. Can someone set me on the right path?

This is your life, and it's ending one minute at a time. - Fight club

Edge Damodred

170

July 29, 2008 08:38 PM

In your rendering code before you draw you need to call cgGLEnableProfile() for both the vertex and fragment shaders. You can store the profiles in a CGprofile parameter, one for each. You can get this once when you're creating the shaders.

-----------------------Or, as I put it, MMORPG's are currently about attaining two primary things: strength and a shovel. The rest is you just shoveling sh** endlessly trying to get stronger to shovel more sh** so you can look for the next new shovel to shovel more sh** with. Once you are done, you can stand on top of a large pile of sh**, raise your golden sh** shoveler up high into the air and boast how proud you are to be the best sh** shoveler of them all. -Griffin_Kemp

EmptyVoid

102

Author

July 29, 2008 09:04 PM

Quote:Original post by Edge Damodred
In your rendering code before you draw you need to call cgGLEnableProfile() for both the vertex and fragment shaders. You can store the profiles in a CGprofile parameter, one for each. You can get this once when you're creating the shaders.

Ok will that make them work together?

This is your life, and it's ending one minute at a time. - Fight club

Edge Damodred

170

July 30, 2008 12:54 AM

What do you mean by making them work together? It might help if you posted your shader code and what you're trying to make happen.

-----------------------Or, as I put it, MMORPG's are currently about attaining two primary things: strength and a shovel. The rest is you just shoveling sh** endlessly trying to get stronger to shovel more sh** so you can look for the next new shovel to shovel more sh** with. Once you are done, you can stand on top of a large pile of sh**, raise your golden sh** shoveler up high into the air and boast how proud you are to be the best sh** shoveler of them all. -Griffin_Kemp

EmptyVoid

102

Author

July 30, 2008 02:53 AM

Quote:Original post by Edge Damodred
What do you mean by making them work together? It might help if you posted your shader code and what you're trying to make happen.

cgGLEnableProfile did work thanks!

This is your life, and it's ending one minute at a time. - Fight club

EmptyVoid

102

Author

July 30, 2008 03:03 AM

Actually I have one more question, when I remove both cgGLBindProgram statements it seems to still work fine. So my question is what does cgGLBindProgram do?

This is your life, and it's ending one minute at a time. - Fight club

Edge Damodred

170

July 30, 2008 06:44 PM

cgGLBindProgram() basically tells the rendering pipeline to ignore OpenGL's Fixed Function commands. If all your shaders are doing is passing stuff through the vertex and fragment processors, you're not going to notice any difference between the shader code and OpenGL's pipeline. However if in your vertex shader you tell it to specifically assign a specific color to a vertex, it won't matter what color you tell OpenGL that vertex should be, your shader will override it as long as the vertex program is bound.

-----------------------Or, as I put it, MMORPG's are currently about attaining two primary things: strength and a shovel. The rest is you just shoveling sh** endlessly trying to get stronger to shovel more sh** so you can look for the next new shovel to shovel more sh** with. Once you are done, you can stand on top of a large pile of sh**, raise your golden sh** shoveler up high into the air and boast how proud you are to be the best sh** shoveler of them all. -Griffin_Kemp

How to get a CG vertex and pixel shader to work together?

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