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Vertex Array Texture Binding Problem

Started by Butterman Feb 22, 2009 at 11:30 AM 7 replies 1.5k views

Original Post

Feb 22, 2009 at 11:30 AM

Hey guys. I'm trying to bind textures to models I'm loading to my custom format. It all worked perfectly fine when I was using (glBegin(), glEnd(), glVertex3f(), glTexCoord2d(), etc). But I'm moving over to Vertex Arrays because that's all my target platform supports. Here is a video from when it was working.

I just modified my code, using the same variable format. Now I get this.

Here is my current drawing code.



static void DrawJModel(JModel *model, int frame = 0)
	{
		glTranslatef(model->X,model->Y,model->Z);
		glRotatef(model->angleY + 180,0,1,0);
		glScalef(0.7,0.7,0.7);

		glEnableClientState(GL_VERTEX_ARRAY);
		glEnableClientState(GL_TEXTURE_COORD_ARRAY);

		glVertexPointer(3, GL_FLOAT, 0, model->frames[frame].verticies);

		for(int b = 0; b < model->tFaces; b++)
		{
			glTexCoordPointer(2,GL_FLOAT,0, &model->faces.UV[0]);

			std::cout << model->faces.UV[4] << " " << model->faces.UV[5] << std::endl;

			if(model->faces.num == 3)
			{
				glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, model->faces.indicies);
			}
			else
			{
				glDrawElements(GL_QUADS, 4, GL_UNSIGNED_BYTE, model->faces.indicies);
			}
		}

		glDisableClientState(GL_TEXTURE_COORD_ARRAY);
		glDisableClientState(GL_VERTEX_ARRAY);
	}

I know the UVs are getting loaded fine, they worked fine before and as you can see I'm even outputting the UVs as they're drawn to make sure they're intact. Even still, here is a snippet from my loading code.


//For each face in the model
		for(int i = 0; i < temp.tFaces; i++)
		{
			//Read in the number of indicies in the face
			fscanf(pFile,"\n %i ",&temp.faces.num);

			//Create room for the uv depending on the number of indicies, we need a U and a V per index
			//temp.faces->UV = new GLfloat[temp.faces.num * 2 + 2];

			//For each of the indicies in the face
			for(int c = 0; c < temp.faces.num; c++)
			{
				//Load up their index and UV co-ordinates
				fscanf(pFile,"%i %f %f ", &temp.faces.indicies[c], 
					&temp.faces.UV[(c * 2)], 
					&temp.faces.UV[((c * 2) + 1)]);
			}

		}

I've been working at this problem most of last week, any help is great :D Cheers!

Great_White

Feb 22, 2009 at 11:43 AM

not sure about this but may be you should not set the stride parameter correctly when calling gl*Pointer().Are you using interleave format for vertex data ? Also instead of calling glDrawElements() for every faces you can call it once with all the faces.

Butterman

Author

Butterman

Feb 22, 2009 at 11:50 AM

There is no stride. Each UV array is a fixed 10 float array. That goes, U,V,U,V,U,V for each of the indicies in its face. (One UV array per face). So, it's just size two. I'm not interweaving any data.

I can't just call DrawElements, because I have to provide GL_QUADS or GL_TRIANGLES, my model format supports faces with 3 or 4 verticies.

As you can see the model is drawing fine, it's just the texture.

scratt

Feb 22, 2009 at 12:04 PM

Your GL code looks ok.

How is your structure arranged for your faces / UV coords.

What I am driving at here is.. If you were sending them up before with individual commands for each vertex and now you are sending them in small batches with DrawArrays and pointers.. Are the UV coords all sequential in memory?

Butterman

Author

Butterman

Feb 22, 2009 at 12:12 PM

Urm. I don't know what I can show you about UV arrangement apart from what was in my loading code above.

struct face{	int num;	GLubyte indicies[5];	GLfloat UV[20];};struct frame{	float *verticies;};struct JModel{	int tVerticies;	int tFrames;	int tFaces;	face *faces;	frame *frames;	float angleY;	float X,Y,Z;};

//For each face in the model		for(int i = 0; i < temp.tFaces; i++)		{			//Read in the number of indicies in the face			fscanf(pFile,"\n %i ",&temp.faces.num);			//Create room for the uv depending on the number of indicies, we need a U and a V per index			//temp.faces->UV = new GLfloat[temp.faces.num * 2 + 2];			//For each of the indicies in the face			for(int c = 0; c < temp.faces.num; c++)			{				//Load up their index and UV co-ordinates				fscanf(pFile,"%i %f %f ", &temp.faces.indicies[c], 					&temp.faces.UV[(c * 2)], 					&temp.faces.UV[((c * 2) + 1)]);			}		}

The key here is this.

//Load up their index and UV co-ordinatesfscanf(pFile,"%i %f %f ", &temp.faces.indicies[c], 		&temp.faces.UV[(c * 2)], 		&temp.faces.UV[((c * 2) + 1)]);

You can see that I'm getting the index then its two UV co-ordinates. Each line in the model file holds 3 or 4 different index, UV pairs. That's what C is, I check how many indicies are in the face, then loop through them with C.

Here is a sample face from the format.

4 23 0.121100 0.332000 32 0.121100 0.363300 38 0.003900 0.363300 35 0.019500 0.332000

As you can see, "4" faces, then "23" index, "0.12", "0.33" U and V then we have another index "32".

I'm almost 100% certain that it's going in fine. But I'm also 100% certain that this is where the problem is at.

scratt

Feb 23, 2009 at 2:14 AM

OK. I think I may know what it is... I am dredging my memory here but... I am pretty sure that when you use indexed arrays then the index affects all data sources... I seem to remember falling foul of this when I tried to do a cheap instanced vertex method on earlier shader models to draw QUADs super fast.

So you would need to have UV pairs in a general array that matches up to the vertex array.

i.e. Index 1 refers to both Vertex 1 and UV pair 1. Index 10 refers to Vertex 10 and UV pair 10.

Does that make sense to you?

Butterman

Author

Butterman

Feb 23, 2009 at 2:28 AM

Yeah. Perfect sense. That would explain every thing.

I'll sort that out when I get home tonight. Thanks a lot man.

scratt

Feb 23, 2009 at 2:30 AM

np :)

Butterman

Author

Butterman

Feb 23, 2009 at 10:12 AM

Well. It's done. Took one hell of a hack. I just can't see any other way of getting it working with my current format. I really like the fact that I don't have to store more than one of every vertex, but if my UV list has to match my Vertex list, well, that isn't going to work because the UV depends on the current face.

Here's my hack, tell me how bad it is. (If at all)

                //New		GLfloat *UV = new GLfloat[model->tVerticies *2];		glTranslatef(model->X,model->Y,model->Z);		glRotatef(model->angleY + 180,0,1,0);		glScalef(0.7,0.7,0.7);		glEnableClientState(GL_VERTEX_ARRAY);		glEnableClientState(GL_TEXTURE_COORD_ARRAY);		glVertexPointer(3, GL_FLOAT, 0, model->frames[frame].verticies);		glTexCoordPointer(2,GL_FLOAT,0, UV);		for(int b = 0; b < model->tFaces; b++)		{			if(model->faces.num == 3)			{                                //New				for(int c = 0; c < 3; c++)				{                                               //New					UV[(model->faces.indicies[c]) * 2] = model->faces.UV[(c * 2)];					UV[(model->faces.indicies[c]) * 2 + 1] = model->faces.UV[(c * 2) + 1];				}				glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, model->faces.indicies);			}			else			{				for(int c = 0; c < 4; c++)				{					UV[(model->faces.indicies[c]) * 2] = model->faces.UV[(c * 2)];					UV[(model->faces.indicies[c]) * 2 + 1] = model->faces.UV[(c * 2) + 1];				}				glDrawElements(GL_QUADS, 4, GL_UNSIGNED_BYTE, model->faces.indicies);			}		}		glDisableClientState(GL_TEXTURE_COORD_ARRAY);		glDisableClientState(GL_VERTEX_ARRAY);		delete(UV);

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