glUniform [ i ] fvARB problem

[Zulfiqar Malik]

I was using glUniform3fvARB(location, count, *value); for passing vectors to a vertex shader and i noticed (after a day of banging!) that the vector i was passing was not coming out right in the vertex/fragment shader. I read the documentation (both official and also from the Orange Book) and found that the "count" parameter should be the number of items passed i.e. 1 in case you are passing a 3d vector (i was passing a 3d position vector). But nothing seems to be working right, i tried passing 3 and 1 in case of a 3d vector but the results in both cases were inconsistent (from the ones i was getting while using an equivalent CG shader). Is this a known nVidia issue (i am using the latest drivers). Can someone give me more information on this please.

P.S: I then worked around by passing the parameter as glUniform3fARB(...) and that worked out fine without any change in the vs/ps code, but i want to directly pass an array.

[Relic]

Are you sure both the function pointer queried with wglGetProcAddress and the pointer to your data are correct?
Post the code which fails including the data you give to glUniform3fvARB.

[stefan]

I seem to have a similar problem (6629 on SuSE 9.2). I fail to set an array with a length greater than 3. Here's the vertex shader:

void main()
{
	gl_Position = ftransform(); 
}

And here the fragment shader:

uniform float weights[15];
 
void main()
{       
	gl_FragColor=vec4(weights[0],weights[1],weights[2],1.0); 
}

And this code is used to set the uniforms (after activating the shaders):

GLfloat weights[15];
weights[0]=1.0;
weights[1]=0.7;
weights[2]=0.5;
weights[3]=0.4;
GLuint paramWeights=glGetUniformLocationARB(shaderSystem->getHandle(), "weights");	
		glUniform1fvARB(paramWeights,4,weights);

(paramWeights is 0 after the call).
The red component in the fragment shader appears to be 0. If I replace the argument 4 with 3 the red component appears to get the right value 1.
If I try to access the array elements via:

	paramWeights=glGetUniformLocationARB(shaderSystem->getHandle(), "weights[0]");	
glUniform1fARB(paramWeights,weights[0]);
... and so on for 1..3 ...

the value for weight[0] in the fragment shader changes from 1 to 0 as soon as I set the third array element. Again glGetUniformLocationARB returns i for the index i (i.e. a valid value).

[Zulfiqar Malik]

Yeah, the pointer to the function is correct. Here is the vertex program

varying vec3 lightWorldDir;
uniform vec3 lightPos;
void main()
{
gl_Position = ftransform();
lightWorldDir = lightPos - gl_Vertex.xyz;
}

and the fragment program

varying vec3 lightWorldDir;
uniform vec3 spotDir;
void main()
{
vec3 lwdNorm = normalize(-lightWorldDir);
float dp = dot(spotDir, lwdNorm);
gl_FragColor = vec4(dp, dp, dp, dp);
}

and i pass the lightPos and spotDir using the following

glUniform3fvARB(location, 1, lightPos.v);
glUniform3fvARB(location, 1, spotDir.v);

I have tried the following too

glUniform3fvARB(location, 3, lightPos.v);
glUniform3fvARB(location, 3, spotDir.v);

but none seems to work. passing the parameters as:

glUniform3fARB(location, lightPos.x, lightPos.y, lightPos.z);
glUniform3fARB(location, spotDir.x, spotDir.y, spotDir.z);

works fine.