OpenGL - drawing 2D polygons shapes with texture
- by plonkplonk
I am trying to make a few effects in a C+GL game. So far I draw all my sprites as a quad, and it works.
However, I am trying to make a large ring appear at times, with a texture following that ring, as it takes less memory than a quad with the ring texture inside.
The type of ring I want to make is not a round-shaped GL mesh ring (the "tube" type) but a "paper" 2D ring. That way I can modify the "width" of the ring, getting more of the effect than a simple quad+ring texture.
So far all my attempts have been...kind of ridiculous, as I don't understand GL's coordinates too well (and I can't really understand the available documentation...I am just a designer with no coder help or background. A n00b, basically).
glBegin(GL_POLYGON);
for(i = 0;i < 360; i += 10){
glTexCoord2f(0, 0);
glVertex2f(Cos(i)*(H-10),Sin(i)H);
glTexCoord2f(0, HP);
glVertex2f(Sin(i)(H-10),Cos(i)*(H-10));
glTexCoord2f(WP, HP);
glVertex2f(Cos(i)H,Sin(i)(H-10));
glTexCoord2f(WP, 0);
glVertex2f(Sin(i)*H,Cos(i)*H);
} glEnd();
This is my last attempt, and it seems to generate a "sunburst" from the right edge of the circle instead of a ring. It's an amusing effect but definitely not what I want. Other results included the circle looking exactly the same as the quad textured (aka drawing a sprite literally) or something that looked like a pop-art filter, by working on this train of thought.
Seems like my logic here is entirely flawed, so, what would be the easiest way to obtain such a ring? No need to reply in code, just some guidance for a non-math-skilled user...
