1XXX - Not complete yet!!! But pretty close. 2 3Name 4 5 SGIX_blend_alpha_minmax 6 7Name Strings 8 9 GL_SGIX_blend_alpha_minmax 10 11Version 12 13 $Date: 1998/03/31 00:55:21 $ $Revision: 1.3 $ 14 15Number 16 17 119 18 19Dependencies 20 21 EXT_blend_minmax is required 22 EXT_blend_subtract affects the number of values of BLEND_EQUATION_EXT 23 24Overview 25 26 Two additional blending equations are specified using the interface 27 defined by EXT_blend_minmax. These equations are similar to the 28 MIN_EXT and MAX_EXT blending equations, but the outcome for all four 29 color components is determined by a comparison of just the alpha 30 component's source and destination values. These equations are useful 31 in image processing and advanced shading algorithms. 32 33New Procedures and Functions 34 35 None 36 37New Tokens 38 39 Accepted by the <mode> parameter of BlendEquationEXT: 40 41 ALPHA_MIN_SGIX 0x8320 42 ALPHA_MAX_SGIX 0x8321 43 44Additions to Chapter 2 of the GL Specification (OpenGL Operation) 45 46 None 47 48Additions to Chapter 3 of the GL Specification (Rasterization) 49 50 None 51 52Additions to Chapter 4 of the GL Specification (Per-Fragment Operations 53and the Framebuffer) 54 55 Two additional blending equations are defined. If BlendEquationEXT is 56 called with <mode> set to ALPHA_MIN_EXT, the blending equation becomes 57 58 / Cs As < Ad 59 C' = ( 60 \ Cd As >= Ad 61 62 where C' is the color resulting from the blending operation, 63 Cs and Cd are the source and destination colors, and As and Ad 64 are the source and destination alpha in particular. 65 66 If BlendEquationEXT is called with <mode> set to ALPHA_MAX_SGIX, the 67 blending equation becomes 68 69 / Cs As > Ad 70 C' = ( 71 \ Cd As <= Ad 72 73 In both cases the blending equation is evaluated separately for each 74 color component in a quadruplet. 75 76Additions to Chapter 5 of the GL Specification (Special Functions) 77 78 None 79 80Additions to Chapter 6 of the GL Specification (State and State Requests) 81 82 None 83 84Additions to the GLX Specification 85 86 None 87 88GLX Protocol 89 90 None 91 92Dependencies on EXT_blend_minmax 93 94 EXT_blend_minmax is required. 95 96Errors 97 98 INVALID_ENUM is generated by BlendEquationEXT if its single parameter 99 is not FUNC_ADD_EXT, MIN_EXT, MAX_EXT, FUNC_SUBTRACT_EXT, 100 FUNC_REVERSE_SUBTRACT_EXT, ALPHA_MIN_SGIX, or ALPHA_MAX_SGIX. 101 102 INVALID_OPERATION is generated if BlendEquationEXT is executed between 103 the execution of Begin and the corresponding execution to End. 104 105New State 106 107 Two new values of BLEND_EQUATION_EXT: 108 109 Get Value Get Command Type Initial Value Attribute 110 --------- ----------- ---- ------------- --------- 111 BLEND_EQUATION_EXT GetIntegerv Z7 FUNC_ADD_EXT color-buffer 112 113New Implementation Dependent State 114 115 None 116