15bd8deadSopenharmony_ciName 25bd8deadSopenharmony_ci 35bd8deadSopenharmony_ci EXT_blend_subtract 45bd8deadSopenharmony_ci 55bd8deadSopenharmony_ciName Strings 65bd8deadSopenharmony_ci 75bd8deadSopenharmony_ci GL_EXT_blend_subtract 85bd8deadSopenharmony_ci 95bd8deadSopenharmony_ciVersion 105bd8deadSopenharmony_ci 115bd8deadSopenharmony_ci $Date: 1995/03/31 04:40:39 $ $Revision: 1.4 $ 125bd8deadSopenharmony_ci 135bd8deadSopenharmony_ciNumber 145bd8deadSopenharmony_ci 155bd8deadSopenharmony_ci 38 165bd8deadSopenharmony_ci 175bd8deadSopenharmony_ciDependencies 185bd8deadSopenharmony_ci 195bd8deadSopenharmony_ci EXT_blend_minmax affects the definition of this extension 205bd8deadSopenharmony_ci 215bd8deadSopenharmony_ciOverview 225bd8deadSopenharmony_ci 235bd8deadSopenharmony_ci Two additional blending equations are specified using the interface 245bd8deadSopenharmony_ci defined by EXT_blend_minmax. These equations are similar to the 255bd8deadSopenharmony_ci default blending equation, but produce the difference of its left 265bd8deadSopenharmony_ci and right hand sides, rather than the sum. Image differences are 275bd8deadSopenharmony_ci useful in many image processing applications. 285bd8deadSopenharmony_ci 295bd8deadSopenharmony_ciNew Procedures and Functions 305bd8deadSopenharmony_ci 315bd8deadSopenharmony_ci None 325bd8deadSopenharmony_ci 335bd8deadSopenharmony_ciNew Tokens 345bd8deadSopenharmony_ci 355bd8deadSopenharmony_ci Accepted by the <mode> parameter of BlendEquationEXT: 365bd8deadSopenharmony_ci 375bd8deadSopenharmony_ci FUNC_SUBTRACT_EXT 0x800A 385bd8deadSopenharmony_ci FUNC_REVERSE_SUBTRACT_EXT 0x800B 395bd8deadSopenharmony_ci 405bd8deadSopenharmony_ciAdditions to Chapter 2 of the GL Specification (OpenGL Operation) 415bd8deadSopenharmony_ci 425bd8deadSopenharmony_ci None 435bd8deadSopenharmony_ci 445bd8deadSopenharmony_ciAdditions to Chapter 3 of the GL Specification (Rasterization) 455bd8deadSopenharmony_ci 465bd8deadSopenharmony_ci None 475bd8deadSopenharmony_ci 485bd8deadSopenharmony_ciAdditions to Chapter 4 of the GL Specification (Per-Fragment Operations 495bd8deadSopenharmony_ciand the Framebuffer) 505bd8deadSopenharmony_ci 515bd8deadSopenharmony_ci Two additional blending equations are defined. If BlendEquationEXT is 525bd8deadSopenharmony_ci called with <mode> set to FUNC_SUBTRACT_EXT, the blending equation 535bd8deadSopenharmony_ci becomes 545bd8deadSopenharmony_ci 555bd8deadSopenharmony_ci C' = (Cs * S) - (Cd * D) 565bd8deadSopenharmony_ci 575bd8deadSopenharmony_ci / 0.0 C' < 0.0 585bd8deadSopenharmony_ci C = ( 595bd8deadSopenharmony_ci \ C' C' >= 0.0 605bd8deadSopenharmony_ci 615bd8deadSopenharmony_ci where Cs and Cd are the source and destination colors, and S and D are 625bd8deadSopenharmony_ci as specified by BlendFunc. 635bd8deadSopenharmony_ci 645bd8deadSopenharmony_ci If BlendEquationEXT is called with <mode> set to 655bd8deadSopenharmony_ci FUNC_REVERSE_SUBTRACT_EXT, the blending equation becomes 665bd8deadSopenharmony_ci 675bd8deadSopenharmony_ci C' = (Cd * D) - (Cs * S) 685bd8deadSopenharmony_ci 695bd8deadSopenharmony_ci / 0.0 C' < 0.0 705bd8deadSopenharmony_ci C = ( 715bd8deadSopenharmony_ci \ C' C' >= 0.0 725bd8deadSopenharmony_ci 735bd8deadSopenharmony_ci In all cases the blending equation is evaluated separately for each 745bd8deadSopenharmony_ci color component. 755bd8deadSopenharmony_ci 765bd8deadSopenharmony_ciAdditions to Chapter 5 of the GL Specification (Special Functions) 775bd8deadSopenharmony_ci 785bd8deadSopenharmony_ci None 795bd8deadSopenharmony_ci 805bd8deadSopenharmony_ciAdditions to Chapter 6 of the GL Specification (State and State Requests) 815bd8deadSopenharmony_ci 825bd8deadSopenharmony_ci None 835bd8deadSopenharmony_ci 845bd8deadSopenharmony_ciAdditions to the GLX Specification 855bd8deadSopenharmony_ci 865bd8deadSopenharmony_ci None 875bd8deadSopenharmony_ci 885bd8deadSopenharmony_ciGLX Protocol 895bd8deadSopenharmony_ci 905bd8deadSopenharmony_ci None 915bd8deadSopenharmony_ci 925bd8deadSopenharmony_ciDependencies on EXT_blend_minmax 935bd8deadSopenharmony_ci 945bd8deadSopenharmony_ci If this extension is supported, but EXT_blend_minmax is not, then 955bd8deadSopenharmony_ci this extension effectively defines the procedure BlendEquationEXT, its 965bd8deadSopenharmony_ci parameter FUNC_ADD_EXT, and the query target BLEND_EQUATION_EXT, as 975bd8deadSopenharmony_ci described in EXT_blend_minmax. It is therefore as though 985bd8deadSopenharmony_ci EXT_blend_minmax were also supported, except that equations MIN_EXT 995bd8deadSopenharmony_ci and MAX_EXT are not supported. 1005bd8deadSopenharmony_ci 1015bd8deadSopenharmony_ciErrors 1025bd8deadSopenharmony_ci 1035bd8deadSopenharmony_ci INVALID_ENUM is generated by BlendEquationEXT if its single parameter 1045bd8deadSopenharmony_ci is not FUNC_ADD_EXT, MIN_EXT, MAX_EXT, FUNC_SUBTRACT_EXT, or 1055bd8deadSopenharmony_ci FUNC_REVERSE_SUBTRACT_EXT. 1065bd8deadSopenharmony_ci 1075bd8deadSopenharmony_ci INVALID_OPERATION is generated if BlendEquationEXT is executed between 1085bd8deadSopenharmony_ci the execution of Begin and the corresponding execution to End. 1095bd8deadSopenharmony_ci 1105bd8deadSopenharmony_ciNew State 1115bd8deadSopenharmony_ci 1125bd8deadSopenharmony_ci Get Value Get Command Type Initial Value Attribute 1135bd8deadSopenharmony_ci --------- ----------- ---- ------------- --------- 1145bd8deadSopenharmony_ci BLEND_EQUATION_EXT GetIntegerv Z5 FUNC_ADD_EXT color-buffer 1155bd8deadSopenharmony_ci 1165bd8deadSopenharmony_ciNew Implementation Dependent State 1175bd8deadSopenharmony_ci 1185bd8deadSopenharmony_ci None 119