Signature
glDrawElementsInstancedBaseInstance(
GLenum (
mode
)
,
GLsizei (
count
)
,
GLenum (
type
)
,
const void * (
indices
)
,
GLsizei (
instancecount
)
,
GLuint (
baseinstance
)
)-> void
Parameters
| Variables | Description |
|---|---|
| mode |
Specifies what kind of primitives to render.
Symbolic constants
GL_POINTS
,
GL_LINE_STRIP
,
GL_LINE_LOOP
,
GL_LINES
,
GL_LINE_STRIP_ADJACENCY
,
GL_LINES_ADJACENCY
,
GL_TRIANGLE_STRIP
,
GL_TRIANGLE_FAN
,
GL_TRIANGLES
,
GL_TRIANGLE_STRIP_ADJACENCY
,
GL_TRIANGLES_ADJACENCY
and
GL_PATCHES
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.
|
| instancecount |
Specifies the number of instances of the specified range of indices to be rendered.
|
| baseinstance |
Specifies the base instance for use in fetching instanced vertex attributes.
|
Description
glDrawElementsInstancedBaseInstance
behaves identically to
glDrawElements
except that
instancecount
instances of the set of elements are executed and the value of the internal counter
instanceID
advances for each iteration.
instanceID
is an internal 32-bit integer counter
that may be read by a vertex shader as
gl_InstanceID
.
glDrawElementsInstancedBaseInstance
has the same effect as:
if (mode, count, or type is invalid )
generate appropriate error
else {
for (int i = 0; i < instancecount ; i++) {
instanceID = i;
glDrawElements(mode, count, type, indices);
}
instanceID = 0;
}
Specific vertex attributes may be classified as
instanced
through the use of
glVertexAttribDivisor
. Instanced vertex attributes
supply per-instance vertex data to the vertex shader. The index of the vertex fetched from the enabled instanced vertex
attribute arrays is calculated as
. Note that
baseinstance
does not affect the
shader-visible value of
gl_InstanceID
.
Notes
glDrawElementsInstancedBaseInstance
is available only if the GL version is 4.2 or greater.
GL_LINE_STRIP_ADJACENCY
,
GL_LINES_ADJACENCY
,
GL_TRIANGLE_STRIP_ADJACENCY
and
GL_TRIANGLES_ADJACENCY
are available only if the GL version is 3.2 or greater.
Errors
GL_INVALID_ENUM
is generated if
mode
is not one of
GL_POINTS
,
GL_LINE_STRIP
,
GL_LINE_LOOP
,
GL_LINES
,
GL_TRIANGLE_STRIP
,
GL_TRIANGLE_FAN
, or
GL_TRIANGLES
.
GL_INVALID_OPERATION
is generated if a geometry shader is active and
mode
is incompatible with the input primitive type of the geometry shader in the currently installed program object.
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.
Version Support
| glDrawElementsInstancedBaseInstance |
See Also
Copyright
Copyright
2011-2014 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/
.
