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Thread: not working

  1. #1
    Junior Member Newbie
    Join Date
    Jan 2009
    Posts
    19

    not working

    please tell me what is wrong with the following algorithm.i am trying to draw a triangle on the screen using the 3 vertices of the array...

    GLfloat vertices[]={10,0,20,0,20,10,20,20,10,20,0,20,0,10};
    GLubyte coord[]={1,2,3};
    void RenderScene(void)
    {

    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0f,0.0f,0.0f);
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(2,GL_FLOAT,0,vertices);
    glDrawElements(GL_TRIANGLES,3,GL_UNSIGNED_BYTE,coo rd);
    glutSwapBuffers();

    }

  2. #2
    Senior Member Regular Contributor Rosario Leonardi's Avatar
    Join Date
    Aug 2008
    Location
    Italy
    Posts
    356

    Re: not working

    You must set correctly your projection & model view matrix in order to set the camera properly.
    google for glOrtho, glPerspective and glutLookAt

    Another error, you are picking the vertex number 1 2 and 3 of your vector.
    x y
    20, 0
    20, 10
    20, 20
    The three vertex have the same X coordinate, nothing will be drawn.
    ~ ~ I tell you, realtime 3D is made of blood, sweat and screams! ~ ~

  3. #3
    Junior Member Newbie
    Join Date
    Jan 2009
    Posts
    19

    Re: not working

    the problem was , as you said, the fact that the three vertices had the same x coordinate.thank you for your help

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