Texturing TRIANGLES

The easiest thing to do is just find a convention for drawing your squares and stick w/ it. For example, I render all my polygons in clockwise order, so to draw my square as triangles I use a triangle fan function then send the points (0, 0), (0, 1), (1, 1), (1, 0) and your tex. coordinates should recipricate that. If you aren''t using a triangle fan drawing your square using triangles will be a little slower then simply drawing the quad. Check out nehe for more on texture mapping.

When u do texturing on quads, here is what u usually do:

glTexCoord2f(0.0f, 1.0f);
glVertex3f(-1, 1, 0);

// Display the bottom left vertice
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-1, -1, 0);

// Display the bottom right vertice
glTexCoord2f(1.0f, 0.0f);
glVertex3f(1, -1, 0);

// Display the top right vertice
glTexCoord2f(1.0f, 1.0f);
glVertex3f(1, 1, 0);
(code taken directly from gametutorials.com's texturing demo)

ok, now here is how texturing works. given a texture (don't mind my bad diagram);
----------------------
|0,1-------------1,1 |
|--------------------|
|--------------------|
|0,0--------------1,0|
----------------------

those are the coordinates of the texture. now when texturing mapping a triangle, you can take just 3 of those points to make your texture, such as 0,0 1,1 and 1,0. you won't get the whole texture on your triangle, but that's the way you would do it. so:

glTexCoor2f(0.0f, 0.0f);
glVertex3f(1,0,0);
glTexCoor2f(1.0f, 1.0f);
glVertex3f(-1,1,0);
glTexCoor2f(1.0f, 0.0f);
glVertex3f(-1,0,0);

that's how you would texture a triangle



[edited by - BriW111 on November 25, 2003 10:26:58 AM]