Cambridge Mathematics Direct 4 Calculations Pupil's Book

All that we have to do now is draw our particle. Instead of using a textured quad, I've decided to use a textured triangle strip to speed the program up a bit. Most 3D cards can draw triangles alot faster than they can draw quads. Some 3D cards will convert the quad to two triangles for you, but some don't. So we'll do the work ourselves. We start off by telling OpenGL we want to draw a triangle strip.    glBegin(GL_TRIANGLE_STRIP); // Build Quad From A Triangle Strip Quoted directly from the red book: A triangle strip draws a series of triangles (three sided polygons) using vertices V0, V1 , V2, then V2, V1, V3 (note the order), then V2, V3, V4, and so on. The ordering is to ensure that the triangles are all drawn with the same orientation so that the strip can correctly form part of a surface. Preserving the orientation is important for some operations, such as culling. There must be at least 3 points for anything to be drawn. So the first triangle is drawn using vertices 0, 1 and 2. If you look at the picture you'll see that vertex points 0, 1 and 2 do indeed make up the first triangle (top right, top left, bottom right) ...»