Brian Paul | 8420ad9 | 2002-10-02 17:32:26 +0000 | [diff] [blame] | 1 | Name |
| 2 | |
| 3 | MESA_pack_invert |
| 4 | |
| 5 | Name Strings |
| 6 | |
| 7 | GL_MESA_pack_invert |
| 8 | |
| 9 | Contact |
| 10 | |
Brian Paul | d3b09fe | 2004-03-25 01:42:41 +0000 | [diff] [blame] | 11 | Brian Paul, Tungsten Graphics, Inc. (brian.paul 'at' tungstengraphics.com) |
Brian Paul | 8420ad9 | 2002-10-02 17:32:26 +0000 | [diff] [blame] | 12 | Keith Whitwell, Tungsten Graphics, Inc. (keith 'at' tungstengraphics.com) |
| 13 | |
| 14 | Status |
| 15 | |
| 16 | Shipping (Mesa 4.0.4 and later) |
| 17 | |
| 18 | Version |
| 19 | |
| 20 | 1.0 |
| 21 | |
| 22 | Number |
| 23 | |
| 24 | TBD |
| 25 | |
| 26 | Dependencies |
| 27 | |
| 28 | OpenGL 1.0 or later is required |
| 29 | This extensions is written against the OpenGL 1.4 Specification. |
| 30 | |
| 31 | Overview |
| 32 | |
| 33 | This extension adds a new pixel storage parameter to indicate that |
| 34 | images are to be packed in top-to-bottom order instead of OpenGL's |
| 35 | conventional bottom-to-top order. Only pixel packing can be |
| 36 | inverted (i.e. for glReadPixels, glGetTexImage, glGetConvolutionFilter, |
| 37 | etc). |
| 38 | |
| 39 | Almost all known image file formats store images in top-to-bottom |
| 40 | order. As it is, OpenGL reads images from the frame buffer in |
| 41 | bottom-to-top order. Thus, images usually have to be inverted before |
| 42 | writing them to a file with image I/O libraries. This extension |
| 43 | allows images to be read such that inverting isn't needed. |
| 44 | |
| 45 | IP Status |
| 46 | |
| 47 | None |
| 48 | |
| 49 | Issues |
| 50 | |
Nicolas Kaiser | ae5776c | 2011-04-10 09:58:50 -0600 | [diff] [blame] | 51 | 1. Should we also define UNPACK_INVERT_MESA for glDrawPixels, etc? |
Brian Paul | 8420ad9 | 2002-10-02 17:32:26 +0000 | [diff] [blame] | 52 | |
| 53 | Resolved: No, we're only concerned with pixel packing. There are other |
| 54 | solutions for inverting images when using glDrawPixels (negative Y pixel |
| 55 | zoom) or glTexImage (invert the vertex T coordinates). It would be easy |
| 56 | enough to define a complementary extension for pixel packing in the |
| 57 | future if needed. |
| 58 | |
| 59 | New Procedures and Functions |
| 60 | |
| 61 | None |
| 62 | |
| 63 | New Tokens |
| 64 | |
| 65 | Accepted by the <pname> parameter of PixelStorei and PixelStoref |
| 66 | and the <pname> parameter of GetIntegerv, GetFloatv, GetDoublev |
| 67 | and GetBooleanv: |
| 68 | |
| 69 | PACK_INVERT_MESA 0x8758 |
| 70 | |
| 71 | Additions to Chapter 2 of the OpenGL 1.4 Specification (OpenGL Operation) |
| 72 | |
| 73 | None |
| 74 | |
| 75 | Additions to Chapter 3 of the OpenGL 1.4 Specification (Rasterization) |
| 76 | |
| 77 | None |
| 78 | |
| 79 | Additions to Chapter 4 of the OpenGL 1.4 Specification (Per-Fragment |
| 80 | Operations and the Frame Buffer) |
| 81 | |
| 82 | Add the following entry to table 4.4 (PixelStore parameters) on page 182: |
| 83 | |
| 84 | Parameter Name Type Initial Value Valid Range |
| 85 | --------------------------------------------------------- |
| 86 | PACK_INVERT_MESA boolean FALSE TRUE/FALSE |
| 87 | |
| 88 | In the section labeled "Placement in Client Memory" on page 184 |
| 89 | insert the following text into the paragraph before the sentence |
| 90 | that starts with "If the format is RED, GREEN, BLUE...": |
| 91 | |
| 92 | "The parameter PACK_INVERT_MESA controls whether the image is packed |
| 93 | in bottom-to-top order (the default) or top-to-bottom order. Equation |
| 94 | 3.8 is modified as follows: |
| 95 | |
| 96 | ... the first element of the Nth row is indicated by |
| 97 | |
| 98 | p + Nk, if PACK_INVERT_MESA is false |
| 99 | p + k * (H - 1) - Nk, if PACK_INVERT_MESA is true, where H is the |
| 100 | image height |
| 101 | " |
| 102 | |
| 103 | Additions to Chapter 5 of the OpenGL 1.4 Specification (Special Functions) |
| 104 | |
| 105 | None |
| 106 | |
| 107 | Additions to Chapter 6 of the OpenGL 1.4 Specification (State and |
| 108 | State Requests) |
| 109 | |
| 110 | None |
| 111 | |
| 112 | Additions to Appendix A of the OpenGL 1.4 Specification (Invariance) |
| 113 | |
| 114 | None |
| 115 | |
| 116 | Additions to the AGL/GLX/WGL Specifications |
| 117 | |
| 118 | None |
| 119 | |
| 120 | GLX Protocol |
| 121 | |
| 122 | None |
| 123 | |
| 124 | Errors |
| 125 | |
| 126 | None |
| 127 | |
| 128 | New State |
| 129 | |
| 130 | Add the following entry to table 6.20 (Pixels) on page 235: |
| 131 | |
| 132 | Get Value Type Get Cmd Initial Value Description Sec Attribute |
| 133 | -------------------------------------------------------------------------------------------------- |
| 134 | PACK_INVERT_MESA boolean GetBoolean FALSE Value of PACK_INVERT_MESA 4.3.2 pixel-store |
| 135 | |
| 136 | Revision History |
| 137 | |
| 138 | 21 September 2002 - Initial draft |