Name

glDrawArraysInstanced — draw multiple instances of a range of elements

C Specification

void glDrawArraysInstanced(GLenum mode,
 GLint first,
 GLsizei count,
 GLsizei primcount);
 

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.

first

Specifies the starting index in the enabled arrays.

count

Specifies the number of indices to be rendered.

primcount

Specifies the number of instances of the specified range of indices to be rendered.

Description

glDrawArraysInstanced behaves identically to glDrawArrays except that primcount instances of the range of elements are executed. Those attributes that have divisor N where N is other than zero (as specified by glVertexAttribDivisor) advance once every N instances. Thus, the element transferred from instanced vertex attributes is given by:

instance divisor

The value of instance may be read by a vertex shader as gl_InstanceID.

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

If an array corresponding to a generic attribute required by a vertex shader is not enabled, then the corresponding element is taken from the current generic attribute state.

Errors

GL_INVALID_ENUM is generated if mode is not one of the accepted values.

GL_INVALID_VALUE is generated if count or primcount are negative.

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

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).

GL_INVALID_OPERATION is generated if recording the vertices of a primitive to the buffer objects being used for transform feedback purposes would result in either exceeding the limits of any buffer object’s size, or in exceeding the end position offset + size - 1, as set by glBindBufferRange.

See Also

glCheckFramebufferStatus, glDisableVertexAttribArray, glDrawArrays, glDrawElements, glDrawElementsInstanced, glEnableVertexAttribArray , glVertexAttribDivisor

Copyright

Copyright © 2010-2012 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.