glAddSwapHintRectWIN
[New
- Windows 95, OEM Service Release 2]
The glAddSwapHintRectWIN
function specifies a set of rectangles that are to be copied by SwapBuffers.
void glAddSwapHintRectWIN(
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GLint x, |
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GLint y, |
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GLsizei width, |
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GLsizei height |
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); |
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Parameters
x
The x-coordinate
(in window coordinates) of the lower-left corner of the hint region rectangle.
y
The y-coordinate
(in window coordinates) of the lower-left corner of the hint region rectangle.
width
The width of
the hint region rectangle.
height
The height of
the hint region rectangle.
Remarks
The glAddSwapHintRectWIN
function speeds up animation by reducing the amount of repainting between
frames. With glAddSwapHintRectWIN, you specify a set of rectangular
areas that you want copied when you call SwapBuffers. When you do not specify
any rectangles with glAddSwapHintRectWIN before calling SwapBuffers,
the entire frame buffer is swapped. Using glAddSwapHintRectWIN to copy
only parts of the buffer that changed can significantly increase the
performance of SwapBuffers, especially when SwapBuffers is
implemented in software.
The glAddSwapHintRectWIN
function adds a rectangle to the hint region. When the PFD_SWAP_COPY flag of
the PIXELFORMATDESCRIPTOR
pixel format structure is set, SwapBuffers uses this region to clip the
copying of the back buffer to the front buffer. You don t specify
PFD_SWAP_COPY; it is set by capable hardware. The hint region is cleared after
each call to SwapBuffers. With some hardware configurations, SwapBuffers
can ignore the hint region and exchange the entire buffer. SwapBuffers
is implemented by the system, not by the application.
OpenGL
maintains a separate hint region for each window. When you call glAddSwapHintRectWIN
on any rendering contexts associated with a window, the hint rectangles are
combined into a single region.
Call glAddSwapHintRectWIN
with a bounding rectangle for each object drawn for a frame and for each
rectangle cleared to erase previous frame objects.
Note The glAddSwapHintRectWIN
function is an extension function that is not part of the standard OpenGL
library but is part of the GL_WIN_swap_hint extension. To check whether your
implementation of OpenGL supports glAddSwapHintRectWIN, call glGetString(GL_EXTENSIONS).
If it returns GL_WIN_swap_hint, glAddSwapHintRectWIN is supported. To
obtain the address of an extension function, call wglGetProcAddress.
See Also