How can I draw the following figure in opengl?

Question

I need to draw the following figure in openGL.

I tried to do that with polygons like this

glTexCoord2f(0.0f, 0.0f);glVertex3f(9.5f,0,-20);
glTexCoord2f(0.5f, 0.0f);glVertex3f(20,0,-20);
glTexCoord2f(0.0f, 1.0f);glVertex3f(20,0,40);
glTexCoord2f(1.0f, 0.0f);glVertex3f(9.5f,0,40);



glTexCoord2f(0.0f, 0.0f);glVertex3f(9.5f,0,40);
glTexCoord2f(1.0f, 0.0f);glVertex3f(-20,0,40);
glTexCoord2f(0.0f, 1.0f);glVertex3f(-20,0,0);
glTexCoord2f(1.0f, 0.0f);glVertex3f(-3.5f,0,0);
glTexCoord2f(1.0f, 1.0f);glVertex3f(9.5f,0,0);

I didn't get the exact figure, I got the following figure:

can anyone help??

Also, if you're dealing with 2D I'd recommend changing things around so that +Z is 'up' and the X/Y axes work as one might expect. I don't know about you but I find it far easier to think in the XY plane than in the XZ :) — genpfault, May 12 '10 at 22:01

score 4 · Accepted Answer · answered May 12 '10 at 21:43

4

Triangulate your input polygon and render the resulting triangles. GL_POLYGON only works on convex polygons.

Alternatively you can use the stencil buffer to render concave polygons.

answered May 12 '10 at 21:43

genpfault

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This is probably the only few solutions that is the most practical. I would triangulate as well. – Xavier Ho May 12 '10 at 23:13
Thanks for your answer, I'll go with stencil buffer. – Lisa May 12 '10 at 23:32
Please, can you help here http://stackoverflow.com/questions/2823584/opengl-stencil-buffer-problem-wall-window – Lisa May 13 '10 at 00:05

How can I draw the following figure in opengl?

1 Answers1