# OpenGL VBO normals issue

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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:

 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; }; 

My code for the immediate mode rendering is:

 glBegin(GL_TRIANGLES); for(int i = facei.size()-1; i > 0; i--) { glNormal3f(verts[facei.x]->nor.x, verts[facei.x]->nor.y, verts[facei.x]->nor.z); glVertex3f( verts[facei.x]->pos.x, verts[facei.x]->pos.y, verts[facei.x]->pos.z); glNormal3f(verts[facei.y]->nor.x, verts[facei.y]->nor.y, verts[facei.y]->nor.z); glVertex3f( verts[facei.y]->pos.x, verts[facei.y]->pos.y, verts[facei.y]->pos.z); glNormal3f(verts[facei.z]->nor.x, verts[facei.z]->nor.y, verts[facei.z]->nor.z); glVertex3f( verts[facei.z]->pos.x, verts[facei.z]->pos.y, verts[facei.z]->pos.z); } glEnd(); 

and the vbo one:

 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(); } 

and the shader used has the following source code:

vert:

 "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"; 

frag:

 "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" 

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

When I pass the material color info I use:

 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); 

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

 float whitef[4] = {1.0f, 1.0f, 1.0f, 1.0f}; glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, whitef); .......................................................GL_DIFFUSE .......................................................GL_SPECULAR 

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

After I replaced that code with

 int whitei[4] = {255,255,255,255}; glMaterialiv(GL_FRONT_AND_BACK, GL_AMBIENT, whitei) ..................................................................... 

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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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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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.

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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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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I find it this very counter-intuitive, but maybe it's just me

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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So, i'm currently trying to implement an SSAO shader from THIS tutorial and i'm running into a few issues here.
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• Hi,
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To debug I use RenderDocs, but I did not receive good results. In the first attachment is my result, in the second attachment is what should be.
PS. I base on this tutorial https://learnopengl.com/Getting-started/Textures.

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