misc/opengl.md
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---
geometry:
- lmargin=0.9in
- rmargin=0.3in
- tmargin=0.3in
- bmargin=0.5in
- twoside
papersize: A4
...
## Point function
```
glBegin (GL_POINTS)
glVertex* ();
glEnd();
```
- `glVertex()` function is used to specify coordinates of any point on OpenGL
- `*` represents the suffix required
- a number 2,3 or 4 specify the dimensionality
- two dimensional coordinates *(x,y)* is actually a 3d coordinate where z =
0. So *(x,y)* = *(x,y,0)*. Moreover OpenGl represents vertices as four
dimensions.
- suffix code for indicating the data type is as follows: i (integer), s
(short), f (float) and d (double)
- If we use an array to indicate the coordinates of the vertex then we append
a `v`
- **Examples:**
```
glBegin(GL_POINTS)
glVertex2i(50, 100);
lVertex2i(75, 150);
glVertex2i(100, 200);
glEnd();
int point1[] = {50, 100};
int point2[] = {75, 150};
int point3[] = {100, 200};
glBegin(GL_POINTS)
glVertex2iv(point1);
glVertex2iv(point2);
glVertex2iv(point3);
glEnd();
```
## Line Functions
Three line primitive constants:
1. `GL_LINES`
2. `GL_LINE_STRIP`
3. `GL_LINE_LOOP`