Signature
Description
gl_BoundingBox[]
is an array of two vec4 values that should be used instead of the value of
GL_PRIMITIVE_BOUNDING_BOX
as the primitive bounding box (see
glPrimitiveBoundingBox
) for primitives generated
from the output patch.
gl_BoundingBox[]
is
consumed by the tessellation primitive generator, and is not available as an
input to the tessellation evaluation shader.
Notes
If tessellation is active, each invocation of the tessellation control
shader may re-specify the bounding box by writing to the built-in
gl_BoundingBox[]
variable. If the shader statically assigns a value to
any part of this variable, then
gl_BoundingBox[]
is used instead of
the parameters to
glPrimitiveBoundingBox
.
If the shader contains a static assignment
to
gl_BoundingBox[]
and there is an execution path through the shader
that does not write all components of
gl_BoundingBox[]
, the value of
unwritten components and corresponding bounding box coordinates is undefined
for executions of the shader that take that path.
If the tessellation control shader re-specifies the bounding box, the re-specified
value is used for primitives generated from the output patch by
the primitive generator, any primitives emitted by the geometry shader
invocations for those generated primitives, and any primitives further
introduced during clipping.
Version Support
| gl_BoundingBox[] |
See Also
Copyright
Copyright
2015 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/
.