glDrawElements

Name

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, and GL_TRIANGLES are accepted.
count: Specifies the number of elements to be rendered.
type: Specifies the type of the values in indices. Must be GL_UNSIGNED_BYTE or GL_UNSIGNED_SHORT.
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 vertex attribute, you can use glVertexAttribPointer to prespecify separate arrays of vertex attributes 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.

To enable and disable a generic vertex attribute array, call glEnableVertexAttribArray and glDisableVertexAttribArray.

Notes

If the current program object, as set by glUseProgram, is invalid, rendering results are undefined. However, no error is generated for this case.

Errors

GL_INVALID_ENUM is generated if mode is not an accepted value.

GL_INVALID_ENUM is generated if type is not GL_UNSIGNED_BYTE or GL_UNSIGNED_SHORT.

GL_INVALID_VALUE is generated if count is negative.

GL_INVALID_FRAMEBUFFER_OPERATION is generated if the currently bound framebuffer is not framebuffer complete (i.e. the return value from glCheckFramebufferStatus is not GL_FRAMEBUFFER_COMPLETE).