I looked it up to see what the problem was. GL_INVALID_VALUE is generated if program is not a value generated by OpenGL. GL_INVALID_OPERATION is generated if program is not a program object. GL_INVALID_OPERATION is generated if program has not been successfully linked. GL_INVALID_OPERATION is generated if glGetUniformLocation is executed between the execution of glBegin and the corresponding execution of glEnd. I call the function after all the steps so its not any of those errors, I don't have glBegin or glEnd in my program. This function returns -1 if name does not correspond to an active uniform variable in program or if name starts with the reserved prefix "gl_". This is how I called it lightPosLoc = glGetUniformLocationARB(prog,"lightPos"); if(lightPosLoc != -1) { glUniform3fvARB(lightPosLoc,1,lightPos0); } else { MessageBox(NULL,"Did not find a location!?","WTF",MB_OK|MB_ICONINFORMATION); } This is the code for my shader GLcharARB vShaderString[] = "uniform vec3 lightPos;\n" "void main()\n" "{\n" "gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" "vec3 N = normalize(gl_NormalMatrix * gl_Normal);\n" "vec4 V = gl_ModelViewMatrix * gl_Vertex;\n" "vec3 L = normalize(lightPos - V.xyz);\n" "float NdotL = dot(N,L);\n" "gl_FrontColor = gl_Color * vec4(max(0.0,NdotL));\n" "}\n"; So lightPos is an active uniform variable but why is it still returning -1? [Edited by - SirOnion on August 20, 2005 6:23:55 PM]

Everything is compiled and linked correctly otherwise I have message boxes coming up to tell me what went wrong. And the only thing it says when it runs is that It Couldn't Find a Location which si the message box that will come up if after the call to glGetUniformLocation and the location is still -1;

I get 'Application Error' when I try to run ShaderDesigner.

how are you testing it has compiled/linked correctly?

Is the Program in use when checking the values?
If i remember correctly then you have to have called

glUseProgramObjectARB(prog)

before getUniform wil return correct values.

OKay usually when I make these threads I find out I'm an idiot. When I was calling glLinkProgramARB, I was using the string that held the shader as the parameter and not the program object. Whoops. I didn't think that the actual program would compile if I did that. When the shader was compiled,linked,validated I called glGetObjectParameterARB and got the status of each one, and when I had it wrong it didn't tell me anything was wrong. But now it works, thanks for you're help guys.