applying texture to a quad

OpenGL OpenGL: Basic Coding
1

Hi

I am trying to apply a texture to a quad but my screen remains black. Can anyone spot why ?- I have been trying to figure this out but i am obviously overlooking something.


glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,WINDOW_WIDTH,WINDOW_HEIGHT, 0,-1, 1);
   

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

Above, I have the initial setup.

And then when I want to draw, the below code applies.



glClearColor(0,0,0, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

int cameraX=1500;
int cameraY=200;
int cameraZ=2000;

int worldOriginX=1500;
int worldOriginY=0;
int worldOriginZ=1500;

gluLookAt(cameraX,cameraY,cameraZ,worldOriginX,worldOriginY,worldOriginZ,0,1,0);

glEnable(GL_TEXTURE_2D);

//I have a class that loads the texture
Texture t;
t.load("mytexture.png");

glDisable(GL_LIGHTING);
glDisable(GL_DEPTH_TEST);

glBindTexture(GL_TEXTURE_2D,t.getid()); //returns texture id and binds it 
glBegin(GL_QUADS);
        glTexCoord2f(0,0);
        glVertex3f(0, 1500,750 );
        glTexCoord2f(1,0);
        glVertex3f(1500, 1500, 750 );
        glTexCoord2f(1,1);
        glVertex3f(1500 , -50,750 );
        glTexCoord2f(0,1);
        glVertex3f(0, -50, 750);
glEnd();

glBindTexture(GL_TEXTURE_2D,0);
glDisable(GL_TEXTURE_2D);
2

Can you post your TexImage2D and TexParameter code. Maybe the problem is there.

3

If you don’t display a texture but use a colour - does it display correctly?

4

This is one of the things I had done earlier for debugging purposes- trying to colour the quad red, but it didn’t work. It remains black - so obviously the texture itself is not the problem.


glColor4f(1,0,0,1);

glBegin(GL_QUADS);

        glVertex3f(0, 1500,750 );
   
        glVertex3f(1500, 1500, 750 );
     
        glVertex3f(1500 , -50,750 );
        
        glVertex3f(0, -50, 750);
glEnd();
5

Correct - so now start modifying the camera parameters - your camera is above the target looking down so your should be in the xz plane like (0,0,1). Also change you clear colour and see if you window fills with the new colour - this tells you you are not looking in the direction you think. You object also looks like it is vertical so it might be dissappearing from the angle of the camera which is close to vertical.