OpenGL texture coordinates issue

Question

I'm having an issue with texture mapping in OpenGL. I'm attempting to apply different textures to different objects in the scene, but I'm finding that applying a second texture to a second object is changing the texture coordinates (I think) on the first one. The two objects are a cube and a cylinder.

With only one texture enabled, the scene looks like this: enter image description here

If I then enable textures for 1 or more other objects, I see this (I'm not too bothered about the bad texture mapping on the "wheels" right now): enter image description here

What could be causing this? My drawing code for the cube and cylinders is below:

Cube:

    //Alias the values for easier reading
double X = Position().X;
double Y = Position().Y;
double Z = Position().Z;
double W = _fWidth;
double H = _fHeight;
double D = _fDepth;

//Set textures if necessary
if(super._blHasTexture)
{
    super._obTexture.bind(gl);
}

_obTexture.enable(gl);
gl.glColor3f(0.5f, 0.5f, 0.7f);
//Draw

    gl.glBegin(GL2.GL_QUADS);
        //Front
    gl.glNormal3f(0f, 0f, 1f);
    gl.glVertex3d(X, Y, Z);     gl.glTexCoord2f(0f, 0f);
    gl.glVertex3d(X+W, Y, Z);   gl.glTexCoord2f(1f, 0f);
    gl.glVertex3d(X+W, Y-H, Z); gl.glTexCoord2f(1f, 1f);
    gl.glVertex3d(X, Y-H, Z);   gl.glTexCoord2f(0f, 1f);

    //Back
    gl.glNormal3f(0f, 0f, -1f);
    gl.glVertex3d(X, Y, Z-D);   gl.glTexCoord2f(0f, 0f);
    gl.glVertex3d(X+W, Y, Z-D); gl.glTexCoord2f(1f, 0f);
    gl.glVertex3d(X+W, Y-H, Z-D); gl.glTexCoord2f(1f, 1f);
    gl.glVertex3d(X, Y-H, Z-D); gl.glTexCoord2f(0f, 1f);

    //Left
    gl.glNormal3f(-1f, 0f, 0f);
    gl.glVertex3d(X, Y, Z);     gl.glTexCoord2f(0f, 0f);
    gl.glVertex3d(X, Y, Z-D);   gl.glTexCoord2f(1f, 0f);
    gl.glVertex3d(X, Y-H, Z-D); gl.glTexCoord2f(1f, 1f);
    gl.glVertex3d(X, Y-H, Z);   gl.glTexCoord2f(0f, 1f);            

    //Right
    gl.glNormal3f(1f, 0f, 0f);
    gl.glVertex3d(X+W, Y, Z);   gl.glTexCoord2f(0f, 0f);
    gl.glVertex3d(X+W, Y, Z-D); gl.glTexCoord2f(1f, 0f);
    gl.glVertex3d(X+W, Y-H, Z-D); gl.glTexCoord2f(1f, 1f);
    gl.glVertex3d(X+W, Y-H, Z); gl.glTexCoord2f(0f, 1f);

    //Top
    gl.glNormal3f(0f, 1f, 0f);
    gl.glVertex3d(X, Y, Z);     gl.glTexCoord2f(0f, 0f);
    gl.glVertex3d(X+W, Y, Z);   gl.glTexCoord2f(1f, 0f);
    gl.glVertex3d(X+W, Y, Z-D); gl.glTexCoord2f(1f, 1f);
    gl.glVertex3d(X, Y, Z-D);   gl.glTexCoord2f(0f, 1f);

    //Bottom
    gl.glNormal3f(0f, -1f, 0f);
    gl.glVertex3d(X, Y-H, Z);   gl.glTexCoord2f(0f, 0f);
    gl.glVertex3d(X+W, Y-H, Z); gl.glTexCoord2f(1f, 0f);
    gl.glVertex3d(X+W, Y-H, Z-D); gl.glTexCoord2f(1f, 1f);
    gl.glVertex3d(X, Y-H, Z-D); gl.glTexCoord2f(0f, 1f);
gl.glEnd();

_obTexture.disable(gl);

Cylinder:

GLUquadric quad = glu.gluNewQuadric();
glu.gluQuadricTexture(quad, true);  

_obTexture.bind(gl);
_obTexture.enable(gl);

    //Draw the caps
gl.glBegin(GL2.GL_TRIANGLE_FAN);
    gl.glVertex3f(0f, 0f, 0.01f);
    gl.glTexCoord2f(0f, 0f);
    for(int t = 0; t < 20; t++)
    {
        float X = _fRadius * (float)Math.cos(t);
        float Y = _fRadius * (float)Math.sin(t);
        gl.glVertex3f(X, Y, 0.01f);
    }
    gl.glTexCoord2f(1f, 1f);
gl.glEnd();

gl.glBegin(GL2.GL_TRIANGLE_FAN);
    gl.glVertex3f(0f, 0f, -0.01f + _fHeight);
    gl.glTexCoord2f(0f, 0f);
    for(int t = 0; t < 20; t++)
    {
        float X = _fRadius * (float)Math.cos(t);
        float Y = _fRadius * (float)Math.sin(t);
        gl.glVertex3f(X, Y, -0.01f + _fHeight);
    }
        gl.glTexCoord2f(1f, 1f);
gl.glEnd();         

glu.gluCylinder(quad, _fRadius, _fRadius, _fHeight, 20, 1);
_obTexture.disable(gl);

jka6510 jka6510 · Accepted Answer · 2012-02-14T20:39:54

Assign your texture coordinates BEFORE each call to glVertex, not after - calls after that apply to the following glVertex call.

The way you are doing it, the last coordinate set is being applied to the first vertex (i.e. a corner of your cube) in the next render cycle - hence the difference when you render additional objects.

OpenGL texture coordinates issue

1 Answers