Name
gl.DrawElements -- render primitives from array data
Synopsis
gl.DrawElements(mode, indicesArray)
Function
gl.DrawElements() specifies multiple geometric primitives with very few subroutine calls. Instead of calling a GL function to pass each individual vertex, normal, texture coordinate, edge flag, or color, you can prespecify separate arrays of vertices, normals, and so on, and use them to construct a sequence of primitives with a single call to gl.DrawElements().

When gl.DrawElements() is called, it reads sequential elements from an enabled array and constructs a sequence of geometric primitives. mode specifies what kind of primitives are constructed and how the array elements construct these primitives. mode can be set to the symbolic constants #GL_POINTS, #GL_LINE_STRIP, #GL_LINE_LOOP, #GL_LINES, #GL_TRIANGLE_STRIP, #GL_TRIANGLE_FAN, #GL_TRIANGLES, #GL_QUAD_STRIP, #GL_QUADS, and #GL_POLYGON. If more than one array is enabled, each is used. If #GL_VERTEX_ARRAY is not enabled, no geometric primitives are constructed.

Vertex attributes that are modified by gl.DrawElements() have an unspecified value after gl.DrawElements() returns. For example, if #GL_COLOR_ARRAY is enabled, the value of the current color is undefined after gl.DrawElements() executes. Attributes that aren't modified maintain their previous values.

gl.DrawElements() is included in display lists. If gl.DrawElements() is entered into a display list, the necessary array data (determined by the array pointers and enables) is also entered into the display list. Because the array pointers and enables are client-side state, their values affect display lists when the lists are created, not when the lists are executed.

Please consult an OpenGL reference manual for more information.

Inputs
mode
specifies what kind of primitives to render (see above)
indicesArray
specifies an array where the indices are stored; the indices in this array are treated as values of type #GL_UNSIGNED_INT
Errors
#GL_INVALID_ENUM is generated if mode is not an accepted value.

#GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to an enabled array or the element array and the buffer object's data store is currently mapped.

#GL_INVALID_OPERATION is generated if gl.DrawElements() is executed between the execution of glBegin and the corresponding glEnd.


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