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| Name |
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| SUN_get_transparent_index |
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| Name Strings |
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| GLX_SUN_get_transparent_index |
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| Contact |
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| Ron Bielaski, Sun (Ron.Bielaski 'at' eng.sun.com) |
| Jack Middleton, Sun (Jack.Middleton 'at' eng.sun.com) |
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| Status |
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| Shipping |
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| Version |
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| $Date: 1999/12/28 01:40:37 $ $Revision: 1.5 $ |
| SUN Date: 99/06/25 15:07:02 Revision: 1.2 |
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| Number |
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| 183 |
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| Dependencies |
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| None |
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| Overview |
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| Gets the transparent pixel index for an overlay/underlay window pair. |
| |
| New Procedures and Functions |
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| Status glXGetTransparentIndexSUN(Display *dpy, |
| Window overlay, |
| Window underlay, |
| unsigned long *pTransparentIndex) |
| |
| New Tokens |
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| None |
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| Additions to the GL 1.2.1 Specification |
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| None |
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| Additions to the WGL / AGL Specifications |
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| None |
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| Additions to Chapter ??? of the GLX 1.3 Specification |
| |
| (the following needs to be restructured as changes to the spec, |
| rather than a man page) |
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| dpy Specifies the connection to the X server |
| |
| overlay Specifies the overlay Window of an |
| overlay/underlay pair |
| |
| underlay Specifies the underlay Window. |
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| pTransparentIndex Specifies a pointer to the index to be returned |
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| Return |
| ------ |
| |
| If underlay is a Window that has previously been made |
| the current GLXDrawable by the client and a transparent index |
| is available for the Window overlay, returns 1 and sets |
| *pTransparentIndex to the value of the index. Otherwise returns 0. |
| |
| If underlay is equal to None, and if a transparent |
| index is available for overlay that is independent of the |
| underlying Windows returns 1 and sets *pTransparentIndex to |
| the index. Otherwise 0 is returned. |
| |
| |
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| Description |
| ----------- |
| For some overlay Windows (windows created with a visual with GLX_LEVEL > 0), |
| there is a particular color index that when drawn to the framebuffer |
| causes pixels in the Window to be transparent. That is, pixels in the overlay |
| drawn with the transparent index are invisible and the pixels of window(s) |
| beneath the overlay are displayed. |
| |
| On some systems, the transparent pixel index is a constant. |
| |
| On other hardware, the transparent index is a function of the underlying |
| Window (GLX_LEVEL <= 0). |
| |
| Applications may use glXGetTransparentIndexSUN to determine whether |
| a transparent index is available for a particular pair of windows |
| and the value of the transparent index. |
| |
| If glXGetTransparentIndexSun returns 1 after being called with |
| underlay equal to a valid window, then the transparent index is |
| valid only for underlay. underlay must have been previously made |
| the current GLXDrawable of the thread. |
| |
| If a Window other than underlay is directly beneath overlay the |
| results of drawing with the transparentIndex are undefined. |
| |
| If glXGetTransparentIndexSUN returns 1 when the underlay argument is |
| set to None, the transparentIndex is valid for all underlay windows. |
| |
| |
| Caveats |
| ------- |
| When the transparent index is valid only for a particular underlay window, |
| applications should follow the following guidelines to insure proper |
| operation. |
| |
| It is the application's responsibility to ensure that the only window |
| ever underneath overlay is underlay. |
| |
| Ideally, overlay should be created as a child of underlay with the same |
| size and shape. And the application should reshape the overlay window |
| whenever the underlay window is reshaped. This insures that the |
| transparent index makes the overlay transparent. |
| |
| GLX Protocol |
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| No new protocol is need |
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| Errors |
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| BadDrawable if overlay is not a valid Window or if underlay is |
| not a valid Window (except None). |
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| New State |
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| None |
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| New Implementation Dependent State |
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| None |
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| Revision History |
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| 6/24/99 (Jon Leech, SGI) - Added fields from the new extension template. |
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