15bd8deadSopenharmony_ciName 25bd8deadSopenharmony_ci 35bd8deadSopenharmony_ci SGIX_fog_blend_alpha 45bd8deadSopenharmony_ci SGIX_fog_blend_color 55bd8deadSopenharmony_ci 65bd8deadSopenharmony_ciName Strings 75bd8deadSopenharmony_ci 85bd8deadSopenharmony_ci GL_SGIX_fog_blend 95bd8deadSopenharmony_ci 105bd8deadSopenharmony_ciVersion 115bd8deadSopenharmony_ci 125bd8deadSopenharmony_ci $Date: 1997/09/15 19:26:36 $ $Revision: 1.3 $ 135bd8deadSopenharmony_ci 145bd8deadSopenharmony_ciNumber 155bd8deadSopenharmony_ci 165bd8deadSopenharmony_ci ???? 175bd8deadSopenharmony_ci 185bd8deadSopenharmony_ciDependencies 195bd8deadSopenharmony_ci 205bd8deadSopenharmony_ci XXX 215bd8deadSopenharmony_ci 225bd8deadSopenharmony_ciOverview 235bd8deadSopenharmony_ci 245bd8deadSopenharmony_ci This extension affect the way the fog coefficient (f) is used to 255bd8deadSopenharmony_ci blend the rasterized fragments in non-indexed color mode. 265bd8deadSopenharmony_ci When enabled using the GL_FOG_BLEND_ALPHA_SGIX parameter, 275bd8deadSopenharmony_ci the alpha component of the fog color is used to change the 285bd8deadSopenharmony_ci resulting alpha, as well as the RGB components. 295bd8deadSopenharmony_ci The color components may stay unchanged by the fog computation 305bd8deadSopenharmony_ci if the GL_FOG_BLEND_COLOR_SGIX is disabled. 315bd8deadSopenharmony_ci No change is done to the equation C = f*Cr + (1-f)Cf 325bd8deadSopenharmony_ci 335bd8deadSopenharmony_ci 345bd8deadSopenharmony_ciNew Procedures and Functions 355bd8deadSopenharmony_ci 365bd8deadSopenharmony_ci None 375bd8deadSopenharmony_ci 385bd8deadSopenharmony_ciNew Tokens 395bd8deadSopenharmony_ci 405bd8deadSopenharmony_ci Accepted by the <cap> parameter of Enable, Disable, and IsEnabled 415bd8deadSopenharmony_ci 425bd8deadSopenharmony_ci GL_FOG_BLEND_ALPHA_SGIX 0x81FE 435bd8deadSopenharmony_ci GL_FOG_BLEND_COLOR_SGIX 0x81FF 445bd8deadSopenharmony_ci 455bd8deadSopenharmony_ciAdditions to Chapter 2 of the 1.0 Specification (OpenGL Operation) 465bd8deadSopenharmony_ci 475bd8deadSopenharmony_ci None 485bd8deadSopenharmony_ci 495bd8deadSopenharmony_ciAdditions to Chapter 3 of the 1.0 Specification (Rasterization) 505bd8deadSopenharmony_ci 515bd8deadSopenharmony_ci 525bd8deadSopenharmony_ci 3.9 Fog 535bd8deadSopenharmony_ci 545bd8deadSopenharmony_ci ... (The rasterized fragment's A value is not changed by fog blending.)... 555bd8deadSopenharmony_ci is removed and replaced by. 565bd8deadSopenharmony_ci 575bd8deadSopenharmony_ci The rasterized fragment alpha value is not changed by the fog blending, 585bd8deadSopenharmony_ci unless specified otherwise by enabling it with the GL_FOG_BLEND_ALPHA_SGIX 595bd8deadSopenharmony_ci parameter. Color modifications can be turned off by disabling with 605bd8deadSopenharmony_ci the GL_FOG_BLEND_COLOR_SGIX paramater. 615bd8deadSopenharmony_ci 625bd8deadSopenharmony_ci 635bd8deadSopenharmony_ci 645bd8deadSopenharmony_ciAdditions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations 655bd8deadSopenharmony_ciand the Framebuffer) 665bd8deadSopenharmony_ci 675bd8deadSopenharmony_ci None 685bd8deadSopenharmony_ci 695bd8deadSopenharmony_ciAdditions to Chapter 5 of the 1.0 Specification (Special Functions) 705bd8deadSopenharmony_ci 715bd8deadSopenharmony_ci None 725bd8deadSopenharmony_ci 735bd8deadSopenharmony_ciAdditions to Chapter 6 of the 1.0 Specification (State and State Requests) 745bd8deadSopenharmony_ci 755bd8deadSopenharmony_ci Fog alpha blend enable/disable state is checked by calling glIsEnable 765bd8deadSopenharmony_ci function with GL_FOG_BLEND_ALPHA_SGIX parameter. 775bd8deadSopenharmony_ci Fog color blend enable/disable state is checked by calling glIsEnable 785bd8deadSopenharmony_ci function with GL_FOG_BLEND_COLOR_SGIX parameter. 795bd8deadSopenharmony_ci 805bd8deadSopenharmony_ci When PushAttrib is called with FOG_BIT enabled, the state of the 815bd8deadSopenharmony_ci fog color and alpha blend is pushed. When an attribute set 825bd8deadSopenharmony_ci that includes enable information is popped, the state of the fog 835bd8deadSopenharmony_ci color and alpha blend is restored to the pushed value. 845bd8deadSopenharmony_ci 855bd8deadSopenharmony_ciAdditions to the GLX Specification 865bd8deadSopenharmony_ci 875bd8deadSopenharmony_ci None 885bd8deadSopenharmony_ci 895bd8deadSopenharmony_ciErrors 905bd8deadSopenharmony_ci 915bd8deadSopenharmony_ci None 925bd8deadSopenharmony_ci 935bd8deadSopenharmony_ciNew State 945bd8deadSopenharmony_ci 955bd8deadSopenharmony_ci Get Value Get Command Type Initial Value Attribute 965bd8deadSopenharmony_ci --------- ----------- ---- ------------- --------- 975bd8deadSopenharmony_ci FOG_BLEND_ALPHA_SGIX IsEnabled B FALSE fog 985bd8deadSopenharmony_ci FOG_BLEND_COLOR_SGIX IsEnabled B TRUE fog 995bd8deadSopenharmony_ci 1005bd8deadSopenharmony_ci 1015bd8deadSopenharmony_ciNew Implementation Dependent State 1025bd8deadSopenharmony_ci 1035bd8deadSopenharmony_ci None 1045bd8deadSopenharmony_ci 105