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ed209

OpenGL How can I draw a single point?

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Set an appropriate projection with gluOrtho2D, glBegin with GL_POINTS, and draw your point with glVertex2i (with glColor* for color).

Now, this may or may not be an extremely stupid answer. You see, while this is indeed a good and efficient way of drawing a single point, most people who ask "how can I draw a single point?" aren't actually interested in drawing a single point. Rather, they are interested in drawing lots and lots of stuff, a pixel at a time. This is a good way of drawing one point, and a really bad way of drawing millions of points. So if you were mistaken in what you meant to ask, let us know so we can give you a better answer.

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Do remember though that the moment you start using these points to draw something, like a line, a triangle or an image, that's the moment you start misusing them.

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Quote:
Original post by ed209
How do I draw many points in opengl?


use a for loop, or three.




glBegin(GL_POINTS); //set opengl to point drawing mode
for(int x=0; x<128; x+=2)
for(int y=0; y<128; y+=2)
for(int z=0; z<128; z+=2)
{
glColor3f((float)x/128.0f,(float)y/128.0f,(float)z/128.0f); //slightly different colour for each dot
glVertex3f(x,y,z); //draw the point
}
glEnd();//end point drawing mode




you can make this more efficient using vertex arrays (this is VEERY slow when run in real time)

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Do you know how to draw points not only somewhere in space (XYZ) but with per pixel precision. EG. I want to pixel at 8x89y would be red - no matter what ressolution is used by user.

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Thanks for the help, but I have two more questions.

#1 Please answer the above poster's question cause that is also my question.

#2 My goal is to make an nes emulator some day and I was wondering if drawing pixels like this would be sufficient? Or is there another way I should be doing it?

I am using VB by the way and there isn't too much documentation on opengl with VB.

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