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cantrem

OpenGL VBO normals issue

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cantrem    100
This is the first time I'm making a vbo and I bumped into a problem:

When rendering vbos, the object comes out 100% black.

The lookat/perspective matrices are loaded correctly.
Depth test is enabled and working.
I have enabled lighting and set the parameters for GL_LIGHT0.
The object loads correctly (from an .obj file) and has all the vertex positions/normals it needs.
The vbo/ibo generate without errors.
The position data seems correct (as far as I can tell from the black outline).
Using the silly opengl immediate mode the model renders correctly (perfect smooth lighting).
The mesh material has diffuse/ambient/specular values != (0,0,0,0).
The vert/frag/program get compiled and used before the rendering begins.

The vertex structure is the following:

[code]
struct Vertex
{
static const byte POSITION_OFFSET = 0;
static const byte NORMAL_OFFSET = sizeof(Vector3f);
static const byte TANGENT_OFFSET = 2 * sizeof(Vector3f);
static const byte UV_OFFSET = 3 * sizeof(Vector3f);
static const byte COLOR_OFFSET = 3 * sizeof(Vector3f) + sizeof(Vector2f);

Vector3f pos;
Vector3f nor;
Vector3f tan;
Vector2f uv;
Color color;
};
[/code]

My code for the immediate mode rendering is:

[code]
glBegin(GL_TRIANGLES);

for(int i = facei.size()-1; i > 0; i--)
{
glNormal3f(verts[facei[i].x]->nor.x,
verts[facei[i].x]->nor.y,
verts[facei[i].x]->nor.z);

glVertex3f(
verts[facei[i].x]->pos.x,
verts[facei[i].x]->pos.y,
verts[facei[i].x]->pos.z);

glNormal3f(verts[facei[i].y]->nor.x,
verts[facei[i].y]->nor.y,
verts[facei[i].y]->nor.z);

glVertex3f(
verts[facei[i].y]->pos.x,
verts[facei[i].y]->pos.y,
verts[facei[i].y]->pos.z);

glNormal3f(verts[facei[i].z]->nor.x,
verts[facei[i].z]->nor.y,
verts[facei[i].z]->nor.z);

glVertex3f(
verts[facei[i].z]->pos.x,
verts[facei[i].z]->pos.y,
verts[facei[i].z]->pos.z);

}

glEnd();
[/code]

and the vbo one:

[code]
if(rendObj.cpuObject->Visible())
{
useSurface(*rendObj.oglSurface);

glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glMultMatrixf(rendObj.cpuObject->GlobTransformation().components);

glBindBufferARB(GL_ARRAY_BUFFER_ARB, rendObj.oglSurface->vboID); // for vertex coordinates

glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, sizeof(Vertex), Vertex::POSITION_OFFSET);

glEnableClientState(GL_NORMAL_ARRAY);
glNormalPointer(GL_FLOAT, sizeof(Vertex), (void*)Vertex::NORMAL_OFFSET);

glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, rendObj.oglSurface->iboID); // for indices

glDrawElements(GL_TRIANGLES, rendObj.oglSurface->cpuSurface->facei.size() * 3, GL_UNSIGNED_INT, 0);

glDisableClientState(GL_NORMAL_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);

glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, 0);
glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);

glPopMatrix();
}
[/code]

and the shader used has the following source code:

vert:

[code]
"varying vec3 normal, lightDir, eyeVec; \n"
" \n"
"void main() \n"
"{ \n"
" normal = gl_NormalMatrix * gl_Normal; \n"
" \n"
" vec3 vVertex = vec3(gl_ModelViewMatrix * gl_Vertex); \n"
" \n"
" lightDir = vec3(gl_LightSource[0].position.xyz - vVertex); \n"
" eyeVec = -vVertex; \n"
" \n"
" gl_Position = ftransform(); \n"
"} \n\0";
[/code]

frag:

[code]

"varying vec3 normal, lightDir, eyeVec; \n"
" \n"
"void main (void) \n"
"{ \n"
" vec4 final_color = \n"
" (gl_FrontLightModelProduct.sceneColor * gl_FrontMaterial.ambient) + \n"
" (gl_LightSource[0].ambient * gl_FrontMaterial.ambient); \n"
" \n"
" vec3 N = normalize(normal); \n"
" vec3 L = normalize(lightDir); \n"
" \n"
" float lambertTerm = dot(N,L); \n"
" \n"
" if(lambertTerm > 0.0) \n"
" { \n"
" final_color += gl_LightSource[0].diffuse * \n"
" gl_FrontMaterial.diffuse * \n"
" lambertTerm; \n"
" \n"
" vec3 E = normalize(eyeVec); \n"
" vec3 R = reflect(-L, N); \n"
" float specular = pow( max(dot(R, E), 0.0), \n"
" gl_FrontMaterial.shininess ); \n"
" final_color += gl_LightSource[0].specular * \n"
" gl_FrontMaterial.specular * \n"
" specular; \n"
" } \n"
" \n"
" gl_FragColor = final_color; \n"
"} \n\0"

[/code]

Both the immediate mode and vbo rendering is done in the same method, so there is no opengl state change between them (and, of course, I only use one of them and comment out the second when I'm testing).

One more thing that could have relevance is that if I replace the last line of the frag shader with "gl_fragColor = vec4(1.0,0.0,0.0,1.0)" I actually do get a full red mesh.

If anyone knows where I should search for the problem, any help would be appreciated. If I left out relevant information, I'll add it asap, just say.

Thanks!

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cantrem    100
Ok, found out where the problem is, but I still don't get it:

When I pass the material color info I use:

[code]
glMaterialiv(GL_FRONT_AND_BACK, GL_AMBIENT, mat.ambientCol.ToGLintArray());
glMaterialiv(GL_FRONT_AND_BACK, GL_DIFFUSE, mat.diffuseCol.ToGLintArray());
glMaterialiv(GL_FRONT_AND_BACK, GL_SPECULAR, mat.specularCol.ToGLintArray());
glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, mat.shininess);
[/code]

I did a little test, replacing that code with this:

[code]

float whitef[4] = {1.0f, 1.0f, 1.0f, 1.0f};

glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, whitef);
.......................................................GL_DIFFUSE
.......................................................GL_SPECULAR
[/code]

And ta-da, a wild beautiful mesh appears, lighted like never before.

After I replaced that code with

[code]

int whitei[4] = {255,255,255,255};

glMaterialiv(GL_FRONT_AND_BACK, GL_AMBIENT, whitei)
.....................................................................

[/code]

The mesh turned black again.

I don't get it: should I enable something special to be able to pass glMaterialiv parameters? I couldn't find any documentation on this... as far as I can tell, if glMaterialfv works, so should glMaterialiv. But in my case, it does not.

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cengkarim    124
I'm not sure what is wrong here, but it is clearer to define your own uniforms/attributes, much more easier than trying to switch OpenGL's state machine parameters. Define your own material/light parameters in your shaders.

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cantrem    100
[quote name='Karim Kenawy' timestamp='1305452990' post='4811011']
I'm not sure what is wrong here, but it is clearer to define your own uniforms/attributes, much more easier than trying to switch OpenGL's state machine parameters. Define your own material/light parameters in your shaders.
[/quote]

Yep, I found out this thing about 15 mins ago. The 4.0 ogl doesn't even have them anymore.

Also, problem solved: apparently the glMaterial takes colors in the [0-MAX_GLINT] range, not in the [0-255]. I find it this very counter-intuitive, but maybe it's just me. So the problem was that my mesh had the float-equivalent color of 0.000000something instead of 1.0, like I thought it should be.

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V-man    813
[quote] I find it this very counter-intuitive, but maybe it's just me[/quote]
As stated before, stop using fixed function (glMaterial, glLight, glTexEnv).

Also, normally, people use the floating point version of glMaterial. Sounds like you need a "unsigned byte" version but that doesn't exist for glMaterial.

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cantrem    100
[quote name='V-man' timestamp='1305463577' post='4811056']
[quote] I find it this very counter-intuitive, but maybe it's just me[/quote]
As stated before, stop using fixed function (glMaterial, glLight, glTexEnv).

Also, normally, people use the floating point version of glMaterial. Sounds like you need a "unsigned byte" version but that doesn't exist for glMaterial.
[/quote]

As I said, I will. And yea, an "unsigned byte" alternative would look pretty nice, since you usually store a color as a 4 [0-255] values. Thanks for the input!

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