Table of Contents Glide Programming Guide
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| grDepthMask() enables writes to the depth buffer.
The value of grColorMask() and grDepthMask() are ignored during linear frame buffer writes if the pixel pipeline is disabled (see Chapter Chapter 11. ). The default values are FXTRUE, indicating that the associated buffers are writable. 7Swapping BuffersIn a double or triple buffered frame buffer, the next scene will be rendered in a back buffer while the front buffer is being displayed. After an image has been rendered, it is displayed with a call to grBufferSwap(), which exchanges the front and back buffers in the Voodoo Graphics subsystem after swapInterval vertical retraces. If the swapInterval is 0, then the buffer swap does not wait for vertical retrace. If the monitor frequency is 60 Hz, for example, a swapInterval of 3 results in a maximum frame rate of 20 Hz. void grBufferSwap( int swapInterval ) A swapInterval of 0 may result in visual artifacts, such as ‘tearing’, since a buffer swap can occur during the middle of a screen refresh cycle. This setting is very useful in performance monitoring situations, as true rendering performance can be measured without including the time buffer swaps spend waiting for vertical retrace. grBufferSwap() does not wait for the specified vertical blanking period; instead, it queues the buffer swap command and returns immediately. If the application is double buffering, the Voodoo Graphics subsystem will stop rendering and wait until the swap occurs before executing more commands. If the application is triple buffering and the third rendering buffer is available, then rendering commands will take place immediately in the third buffer. A Glide application can poll the Voodoo Graphics subsystem using the grBufferNumPending() function to determine the number of buffers waiting to be viewed, although this is generally not necessary. int grBufferNumPending( void ) Download 6.22 Mb. Share with your friends:
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