3D pyramid appears scattered

I have a struct that I called pyramid:


typedef struct
{
    GLfloat xUp;
    GLfloat yUp;
    GLfloat zUp;
    GLfloat base;
    GLfloat height;
}pyramid;

There are the coordinated of the uppest point:xUp, yUp, zUp.
So when I need to draw the pyramid I just calculate the 4 points that are at the base of the pyramid, then draw the triangles with all the vertices in counter clockwise order:


void drawPyramid(pyramid pyr)
{
    GLfloat p1[]= {pyr.xUp+pyr.base/2.0, pyr.yUp-pyr.height, pyr.zUp-pyr.base/2.0};
    GLfloat p2[]= {pyr.xUp+pyr.base/2.0, pyr.yUp-pyr.height, pyr.zUp+pyr.base/2.0};
    GLfloat p3[]= {pyr.xUp-pyr.base/2.0, pyr.yUp-pyr.height, pyr.zUp+pyr.base/2.0};
    GLfloat p4[]= {pyr.xUp-pyr.base/2.0, pyr.yUp-pyr.height, pyr.zUp-pyr.base/2.0};
    GLfloat up[]= {pyr.xUp, pyr.yUp, pyr.zUp};
    
    glBegin(GL_TRIANGLES);
    
    glColor4f(1.0, 0.0, 0.0, 0.0);
    glVertex3fv(up);
    glVertex3fv(p1);
    glVertex3fv(p2);
    
    glColor4f(0.0, 1.0, 0.0, 0.0);
    glVertex3fv(up);
    glVertex3fv(p2);
    glVertex3fv(p3);
    
    glColor4f(0.0, 0.0, 1.0, 0.0);
    glVertex3fv(up);
    glVertex3fv(p3);
    glVertex3fv(p4);
    
    glColor4f(1.0, 1.0, 0.0, 0.0);
    glVertex3fv(up);
    glVertex3fv(p4);
    glVertex3fv(p1);
    glEnd();
    


    glColor4f(0.0, 1.0, 1.0, 0.0);
    glBegin(GL_QUADS);
    glVertex3fv(p1);
    glVertex3fv(p2);
    glVertex3fv(p3);
    glVertex3fv(p4);
    glEnd();
    
}

I give them different color just to make them more visible.
I am using a perspective projection, and the problem is that the sides of the pyramid appears scattered: it doesn’t even seem a pyramid:

http://www.opengl.org/discussion_boards/attachment.php?attachmentid=906&stc=1&d=1353199239

Lastly I would show how initialize everything:


void init()
{
    glEnable(GL_DEPTH);
    glViewport(-1.0, 1.0, -1.0, 1.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0, 1.0, 1.0, 100.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(0.0, -25.0, 0.0, 0.0, 0.0, 50.0, 0.0, 1.0, 0.0);
}


And this is the function where I render:


void display()
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glTranslatef(0.0, -25.0, 50.0);
    glRotatef(-angle, 0.0, 1.0, 0.0);
    glTranslatef(0.0, 25.0, -50.0);
    
    pyramid pyr;
    pyr.xUp=0.0;
    pyr.yUp=10.0;
    pyr.zUp=50.0;
    pyr.base=10.0;
    pyr.height=18.0;
    glColor4f(1.0, 0.0, 0.0, 0.0);
    drawPyramid(pyr);
    
    glutSwapBuffers();
}

angle is just a float that I use to rotate the pyramid, to see it better.
I would know why sometimes I see three sides (3 different colors) of the pyramix mixed up, like if there aren’t precise sides but there’s jast a triangle embedded in another triangle, and it doesn’t look like a pyramid.

I’m guessing there’s something wrong with your definitions of p1, p2, p3, …
Try drawing one or two faces at time in wireframe mode.
To render the faces in wireframe add one line of code:

  [b]glPolygonMode (GL_FRONT_AND_BACK, GL_LINE);[/b]

Good luck.