Is this Normal for Texturing?

Mars_999
Unregistered
 
Post: #1
In my engine I have the front of my polygons rendered and textured. But when I go behind the polygons I see the back side is textured also? Is this normal if not what would I have to turn on to disable it? I already have these states running.

glEnable(GL_CULL_FACE);
glFrontFace(GL_CCW);
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Moderator
Posts: 771
Joined: 2003.04
Post: #2
I think you can use

glCull(GL_BACK)

(Not sure, have to check)
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henryj
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Post: #3
Yes, this is normal.
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #4
It is?
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Mars_999
Unregistered
 
Post: #5
Quote:Originally posted by PowerMacX
I think you can use

glCull(GL_BACK)

(Not sure, have to check)


One step ahead already have it enabled no difference. I am starting to think henryj is right.
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #6
It works just fine... you must be doing something else wrong.

Code:
#include <stdlib.h>

#if defined(__APPLE_CC__)
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

GLubyte texture[16] =
{
    255, 0, 0, 255,
    0, 255, 0, 255,
    0, 0, 255, 255,
    255, 255, 0, 255
};

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    static GLdouble angle = 0.0;
    angle += 0.001;
    if (angle > 6.283185308)
    {
        angle -= 6.283185308;
    }

    glLoadIdentity();
    gluLookAt(5.0, 5.0, 0.0,
              0.0, 0.0, 0.0,
              0.0, 1.0, 0.0);
    glRotatef(180 * angle / 3.141592654, 0, 1, 0);
    
    glBegin(GL_QUADS);
    glTexCoord2f(0, 0);
    glVertex2f(-1, -1);
    glTexCoord2f(1, 0);
    glVertex2f(1, -1);
    glTexCoord2f(1, 1);
    glVertex2f(1, 1);
    glTexCoord2f(0, 1);
    glVertex2f(-1, 1);
    glEnd();

    glutSwapBuffers();
}

void reshape(int width, int height)
{
    glViewport(0, 0, width, height);
    
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0, (GLdouble)width/(GLdouble)height, 0.01, 100);
    glMatrixMode(GL_MODELVIEW);
}

void idle(void)
{
    glutPostRedisplay();
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(640, 480);

    (void)glutCreateWindow("GLUT Program");
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutIdleFunc(idle);
    
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_CULL_FACE);
    
    glBindTexture(GL_TEXTURE_2D, 1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0,
                 GL_RGBA, GL_UNSIGNED_BYTE, texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    glutMainLoop();

    return EXIT_SUCCESS;
}
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Mars_999
Unregistered
 
Post: #7
Well when I go behind the skybox the polygon disappears. When I go under my 3D terrain the polygons aren't their per se, but I see the textures that are being rendered on the front of them. I am using GL_TRIANGLES_STRIP and the order should be this
0,1
2,3
moving left to right ->
or

1,3
0,2

moving left to right ->


because I am doing the first one.

And these are the functions I have called

glFrontFace(GL_CCW);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
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Mars_999
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Post: #8
Well the issue was windings. Hmmm Bored
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Member
Posts: 148
Joined: 2003.03
Post: #9
Just a wild off-topic thought...is it possible to map two different textures to each face of a polygon?
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Mars_999
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Post: #10
Yes that what I am doing with multitexturing.
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