Is This Not Permitted???
Author
I want to create a flat horizontal circle in the center of my room. I don''t want to go through and specify each vertex by hand. I was hoping this would work, but it does not. Am I doing anything wrong? How can I get this sort of algorithm to work?
GLfloat xTemp;
GLfloat yTemp;
GLfloat count = 50.0;
GLfloat currentAngle = 0.0;
GLfloat theta = 10.0;
GLfloat radius = 44.0;
glBegin(GL_TRIANGLE_STRIP);
glNormal3f(0.0, 0.0, 1.0);
glVertex3f(0.0, 0.0, 73.0);
while (currentAngle <= 360.0)
{
xTemp = cos(currentAngle)/radius;
yTemp = sin(currentAngle)/radius;
glVertex3f(xTemp, yTemp, 73.0);
currentAngle += theta;
}
glEnd();
You might want to use quadratics. It''s simple. Just find it in NeHe''s tutorials for "disk".
I spotted two problems -
should probably be
(multiply instead of divide!)
also, you should be using GL_TRIANGLE_FAN instead of GL_TRIANGLE_STRIP
hope that helps
Enigma
------
...about how we can engage with...
xTemp = cos(currentAngle)/radius;yTemp = sin(currentAngle)/radius; should probably be
xTemp = cos(currentAngle) * radius;yTemp = sin(currentAngle) * radius; (multiply instead of divide!)
also, you should be using GL_TRIANGLE_FAN instead of GL_TRIANGLE_STRIP
hope that helps
Enigma
------
...about how we can engage with...
Quadrics...not quadratics.
Later,
ZE.
//email me.//zealouselixir software.//msdn.//n00biez.//
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Later,
ZE.
//email me.//zealouselixir software.//msdn.//n00biez.//
miscellaneous links
[if you have a link proposal, email me.]
const double DTR = 3.141593 / 180; glTranslatef(0.0f, 0.0f, -5.0f); glBegin(GL_TRIANGLE_FAN); glVertex3f(0.0f, 0.0f, 0.0f); for(int i = 0; i <= 360; i+= 5) glVertex3f(cos(i*DTR), sin(i*DTR), 0); glEnd(); Wrote it in 5 minutes. All it takes is a bit of thought.
Later,
ZE.
P.S. you can change the value in the for loop to determine the number of "wedges" you want, which then determines the blockyness of the circle, but also affects speed.
//email me.//zealouselixir software.//msdn.//n00biez.//
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ZE: why not using glVertex2f ? 
Answer: because it''s a five-minute code !
and BTW, just in case someone didn''t see it : "DTR" stands for "Degree To Radian".
Answer: because it''s a five-minute code !
and BTW, just in case someone didn''t see it : "DTR" stands for "Degree To Radian".
quote:Original post by vincoof
ZE: why not using glVertex2f ?
Answer: because it''s a five-minute code !
and BTW, just in case someone didn''t see it : "DTR" stands for "Degree To Radian".
Why not write look-up tables? Why not tell him how to change the radius?
Because it''s 5 minute code, that''s exactly right. My responsibility is to tell you how to do it. It''s your job to figure out the best way for your circumstances.
Later,
ZE.
//email me.//zealouselixir software.//msdn.//n00biez.//
miscellaneous links
[if you have a link proposal, email me.]
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