gl.DrawElements(mode, indicesArray)
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.
#GL_UNSIGNED_INT
#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.