D
glDrawElements
Chapter 4
119
glDrawElements
glDrawElements: render primitives from array data.
C Specification
void glDrawElements(
GLenum mode,
GLsizei count,
GLenum type,
const GLvoid *indices)
Parameters
mode Specifies what kind of primitives to render. 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 are accepted.
count Specifies the number of elements to be rendered.
type Specifies the type of the values in indices. Must be one of
GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, or
GL_UNSIGNED_INT.
indices Specifies a pointer to the location where the indices are stored.
Description
glDrawElements 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 pre-specify separate arrays of vertexes, normals,
and so on and use them to construct a sequence of primitives with a single call to
glDrawElements.
When glDrawElements is called, it uses count sequential elements from an enabled
array, starting at indices to construct a sequence of geometric primitives. mode specifies
what kind of primitives are constructed, and how the array elements construct these
primitives. 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 glDrawElements have an unspecified value after
glDrawElements returns. For example, if GL_COLOR_ARRAY is enabled, the value of
the current color is undefined after glDrawElements executes. Attributes that aren’t
modified remain well defined.
Notes
glDrawElements is available only if the GL version is 1.1 or greater.
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