glVertex2f(a + x, 700.0f);

OpenGL
1

Ladies Gentlemen,
Please let me ask a theoretical question. In my program in topic Horizontal line crossing a vertical I have glVertex2f(a + x, 700.0f); as well glVertex2f(b + x , 700.0f) defining a line segment. I have modified Mr. Doug Binks suggestion in topic Square is not moving at glfw discussion, but I can’t understand what parameters represent. They seem represent pixels but if the were doing so their type were int.
I’m interested in it for I use x for speed segment.
Then, what these parameters represent?
Thanks in advance. Regards.

2

The arguments to this function represents X and Y point position coordinates in OBJECT space. Each call to this function implicitly defines the corresponding Z and W position coordinates of that point to be 0 and 1, respectively.

And to answer your next question, “you” define what OBJECT space is, by the GL_MODELVIEW and the GL_PROJECTION matrices that you set as active at the time that you render these points. These define how to take the point you provide from your OBJECT space to EYE-SPACE and CLIP-SPACE, respectively.

3

Mr. Dark Photon,
Please accept my many thanks for you answered my question.
Regards.

4

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