glBegin

Description

GL_POINTS

Treats each vertex as a single point. Vertex $\mathit{n}$ defines point $\mathit{n}$ . $\mathit{N}$ points are drawn.

GL_LINES

Treats each pair of vertices as an independent line segment. Vertices $2\mathit{n}-1$ and $2\mathit{n}$ define line $\mathit{n}$ . $\frac{\mathit{N}}{2}$ lines are drawn.

GL_LINE_STRIP

Draws a connected group of line segments from the first vertex to the last. Vertices $\mathit{n}$ and $\mathit{n}+1$ define line $\mathit{n}$ . $\mathit{N}-1$ lines are drawn.

GL_LINE_LOOP

Draws a connected group of line segments from the first vertex to the last, then back to the first. Vertices $\mathit{n}$ and $\mathit{n}+1$ define line $\mathit{n}$ . The last line, however, is defined by vertices $\mathit{N}$ and $1$ . $\mathit{N}$ lines are drawn.

GL_TRIANGLES

Treats each triplet of vertices as an independent triangle. Vertices $3\mathit{n}-2$ , $3\mathit{n}-1$ , and $3\mathit{n}$ define triangle $\mathit{n}$ . $\frac{\mathit{N}}{3}$ triangles are drawn.

GL_TRIANGLE_STRIP

Draws a connected group of triangles. One triangle is defined for each vertex presented after the first two vertices. For odd $\mathit{n}$ , vertices $\mathit{n}$ , $\mathit{n}+1$ , and $\mathit{n}+2$ define triangle $\mathit{n}$ . For even $\mathit{n}$ , vertices $\mathit{n}+1$ , $\mathit{n}$ , and $\mathit{n}+2$ define triangle $\mathit{n}$ . $\mathit{N}-2$ triangles are drawn.

GL_TRIANGLE_FAN

Draws a connected group of triangles. One triangle is defined for each vertex presented after the first two vertices. Vertices $1$ , $\mathit{n}+1$ , and $\mathit{n}+2$ define triangle $\mathit{n}$ . $\mathit{N}-2$ triangles are drawn.

GL_QUADS

Treats each group of four vertices as an independent quadrilateral. Vertices $4\mathit{n}-3$ , $4\mathit{n}-2$ , $4\mathit{n}-1$ , and $4\mathit{n}$ define quadrilateral $\mathit{n}$ . $\frac{\mathit{N}}{4}$ quadrilaterals are drawn.

GL_QUAD_STRIP

Draws a connected group of quadrilaterals. One quadrilateral is defined for each pair of vertices presented after the first pair. Vertices $2\mathit{n}-1$ , $2\mathit{n}$ , $2\mathit{n}+2$ , and $2\mathit{n}+1$ define quadrilateral $\mathit{n}$ . $\frac{\mathit{N}}{2}-1$ quadrilaterals are drawn. Note that the order in which vertices are used to construct a quadrilateral from strip data is different from that used with independent data.

GL_POLYGON

Draws a single, convex polygon. Vertices $1$ through $\mathit{N}$ define this polygon.

Errors

See Also

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