C++: Drawing a 2D disk in OpenGL -

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i've tried write proper function drawing 2d disk on screen opengl few days now, , can't seem right :(

this current code:

void disk( float x, float y, float r, const color& vcolor ) {     glbegin( gl_triangle_fan );         glvertex2f( x, y );         for( float = 0; <= 2 * pi + 0.1; += 0.1 )         {             glvertex2f( x + sin( ) * r, y + cos( ) * r );         }     glend(); }

when zooming in, resulting disk shows spikes, not in edges spikes pointing out.

also function doesn't draw 1 disk only, bit more 1 - means if alpha enabled, results wrong.

  • what need change in function draws disk?

void circle(float x, float y, float r, int segments) {     glbegin( gl_triangle_fan );         glvertex2f(x, y);         for( int n = 0; n <= segments; ++n ) {             float const t = 2 * m_pi * (float)n / (float)segments;             glvertex2f(x + sin(t) * r, y + cos(t) * r);         }     glend(); }

that should rid of overdraw. spikes... picture tell thousand words.


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