| XXX - Obsolete; implemented as part of GL_SGIX_igloo_interface |
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| Name |
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| IGLOO_viewport_offsetXXX |
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| This not an EXT, SGI, SGIS, or SGIX extension. It violates the prefix rules. |
| Also the XXX violates the no-caps in the body of the name rule. |
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| Name Strings |
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| GL_IGLOO_viewport_offsetXXX |
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| These strings should never be returned by glGetString, |
| because I don't expect the get in this extension to be implemented |
| The extension should remain incomplete. |
| The name string here is used solely in the registry. |
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| Version |
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| $Date: 1999/04/03 08:40:52 $ $Revision: 1.2 $ |
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| Number |
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| None |
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| Do we number these??? |
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| Dependencies |
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| This extension has *NO* dependencies. |
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| Overview |
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| When Viewport_Offset is enabled then the viewport transformation is becomes |
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| x_w = (p_x/2) x_d + o_x + 0.5 |
| y_w = (p_y/2) y_d + o_y + 0.5 |
| z_w = . . . same as before. |
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| I believe that this is only useful for emulating IrisGL on top of OpenGL. |
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| New Procedures and Functions |
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| There are no new Procedures for this extension |
| New Tokens |
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| * This list should be complete. It should separate the new tokens |
| * based on which procedures and parameters accept them, and explicitly |
| * list those procedures and parameters. Token suffixes must match the |
| * prefix chosen for the extension name. For example: |
| * |
| * Accepted by the <pname> parameters of GetBooleanv, GetIntegerv, |
| * GetFloatv, and GetDoublev: |
| * |
| * NEW_TOKEN_SGI |
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| IGLOO_OFFSET_VIEWPORT_XXX Is accepted by glEnable and glDisable. |
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| Probably not accepted by the <pname> parameter of glGetBooleanv, and |
| glIsEnabled. |
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| (I do not expect glGet to accept this in most implementations, |
| but techically it should since this is user state.) |
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| If glEnable or glDisable generates an INVALID_ENUM then |
| this extension is not available. |
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| Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation) |
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| Section 2.9.1 (Controlling the viewport) |
| now reads: |
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| "The vertex's window coordinates, (x_w) are given by |
| (y_w) |
| (z_w), |
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| (x_w) ((p_x/2)x_d + o_x + offset) ) |
| (y_w) = ((p_y/2)y_d + o_y + offset) ) |
| (z_w) ([unchanged from versions 1.0]) ) |
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| where offset equals 0.5 if IGLOO_OFFSET_VIEWPORT_XXX is enabled, and 0.0 if it is |
| disabled. |
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| Additions to Chapter 3 of the 1.0 Specification (Rasterization) |
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| NONE |
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| Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations |
| and the Frame Buffer) |
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| NONE |
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| Additions to Chapter 5 of the 1.0 Specification (Special Functions) |
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| * List commands that are not included in display lists (typically Get* |
| * commands) |
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| glGet(IGLOO_OFFSET_VIEWPORT_XXX) will probably not be part of any real implementation. |
| glEnable is already display listable and remains so. |
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| Additions to Chapter 6 of the 1.0 Specification (State and State Requests) |
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| There is one new bit of state. |
| This bit is TRUE if IGLOO_OFFSET_VIEWPORT_XXX is enabled |
| and FALSE otherwise. While this is technically user state, it is not |
| needed by IGLOO. . . |
| It's default value is FALSE. |
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| Additions to the GLX Specification |
| No additions are needed for the GLX Specification |
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| Errors |
| There is no new Error state, but glEnable/glDisable now accepts a the new token. |
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| New State |
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| * Description of all state values in table format. Note that client |
| * state should have "client" listed in the Attrib column. |
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| Initial |
| Get Value Get Command Type Value Attrib |
| --------- ----------- ---- ------- ------ |
| IGLOO_OFFSET_VIEWPORT_XXX glGetBooleanv Bool FALSE enable |
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