OpenGL: Silly texturing problem

[vgo]

After a few years (maybe 5 or 6) I decided to pick up again on OpenGL programming and I ran into a strange problem.

I load 6 textures using the glBitmap.LoadTexture function and I try to render a cube with different texture on each side.

I enable texturing, bind the right texture, set normals, texture coordinates and vertices and I get the last texture I loaded on each side.

What could be wrong? I've done this million times and I even digged up some old code that works and I'm doing exactly the same as in there... ops:

[Traveler]

Are you sure you are using glBindTexture for all sides seperately?

In any case, some sample code would help..

[vgo]

Here's the code:
[pascal]
procedure TSkyBox.Render;
var
i, j: Integer;
begin
glEnable(GL_TEXTURE_2D);
glColor3f(1, 1, 1);
glBegin(GL_QUADS);
for i := 0 to 5 do
begin
glBindTexture(GL_TEXTURE_2D, TexID[i]);
glNormal3fv(@Normals[i]);
for j := 0 to 3 do
begin
glTexCoord2fv(@TexCoord[j]);
glVertex3fv(@Vertices[Quads[i, j]]);
end;
end;
glEnd; // GL_QUADS
glDisable(GL_TEXTURE_2D);
end;
[/pascal]

I had the texture ids written to a log file and they were 1-6, just like they should be with them being the only textures generated so far.
For some reason the binding doesn't work.

[vgo]

Figured it out, I have to bind the texture outside glBegin() - glEnd() blocks.

[pascal]
procedure TSkyBox.Render;
var
i, j: Integer;
begin
glColor3f(1, 1, 1);
glEnable(GL_TEXTURE_2D);
for i := 0 to 5 do
begin
glBindTexture(GL_TEXTURE_2D, TexID[i]);
glBegin(GL_QUADS);
glNormal3fv(@Normals[i]);
for j := 0 to 3 do
begin
glTexCoord2fv(@TexCoord[j]);
glVertex3fv(@Vertices[Quads[i, j]]);
end;
glEnd; // GL_QUADS
end;
glDisable(GL_TEXTURE_2D);
end;
[/pascal]

Guess I have to refresh my memory a bit before moving on to the good stuff...

[michalis]

Hint: You should check glGetError from time to time (e.g. after rendering every frame). This will automatically catch errors like this one, using some disallowed function between glBegin and glEnd.

[vgo]

Yeah, I've already added the check to the main loop. I just couldn't think that I'd run into problems in something as trivial as this.

[vgo]

Looks like that wasn't the end of the problems...

For some reason I get $0502 (invalid operation) everytime I call glEnd()...

Even something as simple as this won't work:
[pascal]
glBegin(GL_QUADS);
glColor3f(0.0, 1.0, 0.0);
glVertex3f( 1.0, 1.0,-1.0);
glVertex3f(-1.0, 1.0,-1.0);
glVertex3f(-1.0, 1.0, 1.0);
glVertex3f( 1.0, 1.0, 1.0);
glEnd();
[/pascal]

[michalis]

Even something as simple as this won't work:
...

This looks like a good code, OpenGL shouldn't complain about this. So the error must be somewhere else. Can you show complete code that doesn't work ?

Also you can always check glGetError more often, this should give you more precise hints which operation is invalid. (But remember that glGetError is not allowed between glBegin...glEnd, so you can't put it there).

[Clootie]

Try GLexpert

[vgo]

Here's the simplified rendering code that still produces the error.
[pascal]
procedure glCheckForError;
var
glError: TGLenum;
begin
glError := glGetError();
if (glError <> GL_NO_ERROR) then
raise EOpenGLError.Create('OpenGL error! Code: ' +
IntToStr(glError) + ' ($' + IntToHex(glError, 4) + ' hex) Description: ' +
gluErrorString(glError));
end;

procedure Init;
begin
glClearColor(0.0, 0.0, 0.0, 0.0);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);
glEnable(GL_DEPTH_TEST);
glCullFace(GL_BACK);
glFrontFace(GL_CCW);
glShadeModel(GL_SMOOTH);
glMatrixMode(GL_MODELVIEW);
end;

procedure Render;
begin
glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT);
glLoadIdentity();

glRotatef(-FCamera.Pitch, 1, 0, 0);
glRotatef(-FCamera.Yaw, 0, 1, 0);
glTranslatef(-FCamera.Pos.x, -FCamera.Pos.y, -FCamera.Pos.z);
glCheckForError(); // Everything is ok here

glBegin(GL_QUADS);
glColor3f(0.0, 1.0, 0.0);
glVertex3f( 1.0, 1.0,-1.0);
glVertex3f(-1.0, 1.0,-1.0);
glVertex3f(-1.0, 1.0, 1.0);
glVertex3f( 1.0, 1.0, 1.0);
glEnd();
glCheckForError(); // $0502 GL_INVALID_OPERATION here
end;
[/pascal]

Rendering actually works and everything is rendered correctly, but I just always get the error from each glEnd() call. Doesn't matter what primitives I try to draw, quads, triangles, lines, points, it's all the same...

I'm using the latest version of dglOpenGL and I use a custom panel component for rendering. I have Radeon 9800Pro with latest drivers, running on WinXP corporate edition with all latest patches. I'm using Borland Developer Studio 2006 Architect to write the code.

Try GLexpert

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