Mercurial > sdl-ios-xcode
diff src/video/SDL_renderer_gl.c @ 2848:8a3aa505ecba
Comment cleanup.
author | Ryan C. Gordon <icculus@icculus.org> |
---|---|
date | Sun, 07 Dec 2008 07:16:40 +0000 |
parents | 7d020441fa81 |
children | a38fcb093081 |
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--- a/src/video/SDL_renderer_gl.c Sun Dec 07 07:06:34 2008 +0000 +++ b/src/video/SDL_renderer_gl.c Sun Dec 07 07:16:40 2008 +0000 @@ -528,64 +528,68 @@ data->glBindProgramARB(shader_type, 0); data->glDeleteProgramsARB(1, &program); return 0; - } // if + } return program; } -// UYVY to RGB equasion... -// R = 1.164(Y-16) + 1.596(Cr-128) -// G = 1.164(Y-16) - 0.813(Cr-128) - 0.391(Cb-128) -// B = 1.164(Y-16) + 2.018(Cb-128) -// Byte layout is Cb, Y1, Cr, Y2. -// 4 bytes == 2 pixels: Y1/Cb/Cr, Y2/Cb/Cr -// !!! FIXME: this ignores blendmodes, etc. -// !!! FIXME: this could be more efficient...use a dot product for green, etc. + +/* + * Fragment program that renders from UYVY textures. + * The UYVY to RGB equasion is: + * R = 1.164(Y-16) + 1.596(Cr-128) + * G = 1.164(Y-16) - 0.813(Cr-128) - 0.391(Cb-128) + * B = 1.164(Y-16) + 2.018(Cb-128) + * Byte layout is Cb, Y1, Cr, Y2, stored in the R, G, B, A channels. + * 4 bytes == 2 pixels: Y1/Cb/Cr, Y2/Cb/Cr + * + * !!! FIXME: this ignores blendmodes, etc. + * !!! FIXME: this could be more efficient...use a dot product for green, etc. + */ static const char *fragment_program_UYVY_source_code = "!!ARBfp1.0\n" - // outputs... + /* outputs... */ "OUTPUT outcolor = result.color;\n" - // scratch registers... + /* scratch registers... */ "TEMP uyvy;\n" "TEMP luminance;\n" "TEMP work;\n" - // We need 32 bits to store the data, but each pixel is 16 bits in itself. - // halve the coordinates to grab the correct 32 bits for the fragment. + /* Halve the coordinates to grab the correct 32 bits for the fragment. */ "MUL work, fragment.texcoord, { 0.5, 1.0, 1.0, 1.0 };\n" - // Sample the YUV texture. Cb, Y1, Cr, Y2, are stored x,y,z,w + /* Sample the YUV texture. Cb, Y1, Cr, Y2, are stored in x, y, z, w. */ "TEX uyvy, work, texture[0], %TEXTURETARGET%;\n" - // Do subtractions (128/255, 16/255, 128/255, 16/255) + /* Do subtractions (128/255, 16/255, 128/255, 16/255) */ "SUB uyvy, uyvy, { 0.501960784313726, 0.06274509803922, 0.501960784313726, 0.06274509803922 };\n" - // Choose the luminance component by texcoord. - // !!! FIXME: laziness wins out for now... just average Y1 and Y2. + /* Choose the luminance component by texcoord. */ + /* !!! FIXME: laziness wins out for now... just average Y1 and Y2. */ "ADD luminance, uyvy.yyyy, uyvy.wwww;\n" "MUL luminance, luminance, { 0.5, 0.5, 0.5, 0.5 };\n" - // Multiply luminance by its magic value. + /* Multiply luminance by its magic value. */ "MUL luminance, luminance, { 1.164, 1.164, 1.164, 1.164 };\n" - // uyvy.xyzw becomes Cr/Cr/Cb/Cb, with multiplications. + /* uyvy.xyzw becomes Cr/Cr/Cb/Cb, with multiplications. */ "MUL uyvy, uyvy.zzxx, { 1.596, -0.813, 2.018, -0.391 };\n" - // Add luminance Cr and Cb, store to RGB channels. + /* Add luminance to Cr and Cb, store to RGB channels. */ "ADD work.rgb, luminance, uyvy;\n" - // Do final addition for Green channel. (!!! FIXME: this should be a DPH?) + /* Do final addition for Green channel. (!!! FIXME: this should be a DPH?) */ "ADD work.g, work.g, uyvy.w;\n" - // Make sure alpha channel is fully opaque. (!!! FIXME: blend modes!) + /* Make sure alpha channel is fully opaque. (!!! FIXME: blend modes!) */ "MOV work.a, { 1.0 };\n" - // Store out the final fragment color. + /* Store out the final fragment color... */ "MOV outcolor, work;\n" - // ...and we're done. + /* ...and we're done! */ "END\n";