algortims for making circles in opengl
Author
is there a way to make a circle out of triangles in opengl. i figure if the vertices are close enough it could look like a circle. any help would be appreciated
use GL_TRIANGLE FAN. start with a center point, and then plot however many points you want in r*cos(angle) and r*sin(angle) fashion, where those two cos/sin statements are the x,y coords, and r is the radius.
Author
Im not sure exactly what you mean by that, could you maybe show the a sample of actual code that would do all that you said. thanks
sure.
(this is pseudocode, cuz i'm not sure if it'll compile, but i'll try to make it almost code.)
#define DTR //degrees to radians (2pi/360)
GLfloat center[2] = {30,30};
GLfloat radius = 10.0;
glBegin(GL_TRIANGLE_FAN);
glVertex2d(center[0], center[1]);
for (int angle = 0; angle <=360; angle ++)
{
glVertex2d(center[0] + (radius * cos(angle * DTR)),
center[1] + (radius * sin(angle * DTR));
}
glEnd();
// this code should render a circle with a refinement of
// every degree out of 360. i don't think you necessarily
// need a refinement of 360 degrees, but if not, just
//change the increment value of angle by a factor of 360.
a2k
Edited by - a2k on 4/19/00 8:06:26 PM
Edited by - a2k on 4/19/00 8:12:08 PM
Edited by - a2k on 4/19/00 8:13:38 PM
(this is pseudocode, cuz i'm not sure if it'll compile, but i'll try to make it almost code.)
#define DTR //degrees to radians (2pi/360)
GLfloat center[2] = {30,30};
GLfloat radius = 10.0;
glBegin(GL_TRIANGLE_FAN);
glVertex2d(center[0], center[1]);
for (int angle = 0; angle <=360; angle ++)
{
glVertex2d(center[0] + (radius * cos(angle * DTR)),
center[1] + (radius * sin(angle * DTR));
}
glEnd();
// this code should render a circle with a refinement of
// every degree out of 360. i don't think you necessarily
// need a refinement of 360 degrees, but if not, just
//change the increment value of angle by a factor of 360.
a2k
Edited by - a2k on 4/19/00 8:06:26 PM
Edited by - a2k on 4/19/00 8:12:08 PM
Edited by - a2k on 4/19/00 8:13:38 PM
This topic is closed to new replies.
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