src/gallium/auxiliary/util/u_blend.h

   1 #ifndef U_BLEND_H
   2 #define U_BLEND_H
   3
   4 #include "pipe/p_state.h"
   5 #include "compiler/shader_enums.h"
   6
   7 /**
   8  * When faking RGBX render target formats with RGBA ones, the blender is still
   9  * supposed to treat the destination's alpha channel as 1 instead of the
  10  * garbage that's there. Return a blend factor that will take that into
  11  * account.
  12  */
  13 static inline int
  14 util_blend_dst_alpha_to_one(int factor)
  15 {
  16    switch (factor) {
  17    case PIPE_BLENDFACTOR_DST_ALPHA:
  18       return PIPE_BLENDFACTOR_ONE;
  19    case PIPE_BLENDFACTOR_INV_DST_ALPHA:
  20       return PIPE_BLENDFACTOR_ZERO;
  21    default:
  22       return factor;
  23    }
  24 }
  25
  26 /** To lower blending to software shaders, the Gallium blend mode has to
  27  * be translated to something API-agnostic, as defined in shader_enums.h
  28  * */
  29
  30 static inline enum blend_func
  31 util_blend_func_to_shader(enum pipe_blend_func func)
  32 {
  33    switch (func) {
  34       case PIPE_BLEND_ADD:
  35          return BLEND_FUNC_ADD;
  36       case PIPE_BLEND_SUBTRACT:
  37          return BLEND_FUNC_SUBTRACT;
  38       case PIPE_BLEND_REVERSE_SUBTRACT:
  39          return BLEND_FUNC_REVERSE_SUBTRACT;
  40       case PIPE_BLEND_MIN:
  41          return BLEND_FUNC_MIN;
  42       case PIPE_BLEND_MAX:
  43          return BLEND_FUNC_MAX;
  44       default:
  45          unreachable("Invalid blend function");
  46    }
  47 }
  48
  49 static inline enum blend_factor
  50 util_blend_factor_to_shader(enum pipe_blendfactor factor)
  51 {
  52    switch (factor) {
  53       case PIPE_BLENDFACTOR_ZERO:
  54       case PIPE_BLENDFACTOR_ONE:
  55          return BLEND_FACTOR_ZERO;
  56
  57       case PIPE_BLENDFACTOR_SRC_COLOR:
  58       case PIPE_BLENDFACTOR_INV_SRC_COLOR:
  59          return BLEND_FACTOR_SRC_COLOR;
  60
  61       case PIPE_BLENDFACTOR_SRC_ALPHA:
  62       case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
  63          return BLEND_FACTOR_SRC_ALPHA;
  64
  65       case PIPE_BLENDFACTOR_DST_ALPHA:
  66       case PIPE_BLENDFACTOR_INV_DST_ALPHA:
  67          return BLEND_FACTOR_DST_ALPHA;
  68
  69       case PIPE_BLENDFACTOR_DST_COLOR:
  70       case PIPE_BLENDFACTOR_INV_DST_COLOR:
  71          return BLEND_FACTOR_DST_COLOR;
  72
  73       case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
  74          return BLEND_FACTOR_SRC_ALPHA_SATURATE;
  75
  76       case PIPE_BLENDFACTOR_CONST_COLOR:
  77       case PIPE_BLENDFACTOR_INV_CONST_COLOR:
  78          return BLEND_FACTOR_CONSTANT_COLOR;
  79
  80       case PIPE_BLENDFACTOR_CONST_ALPHA:
  81       case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
  82          return BLEND_FACTOR_CONSTANT_ALPHA;
  83
  84       case PIPE_BLENDFACTOR_SRC1_COLOR:
  85       case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
  86          return BLEND_FACTOR_SRC1_COLOR;
  87
  88       case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
  89       case PIPE_BLENDFACTOR_SRC1_ALPHA:
  90          return BLEND_FACTOR_SRC1_ALPHA;
  91
  92       default:
  93          unreachable("Invalid factor");
  94    }
  95 }
  96
  97 static inline bool
  98 util_blend_factor_is_inverted(enum pipe_blendfactor factor)
  99 {
 100    switch (factor) {
 101       case PIPE_BLENDFACTOR_ONE:
 102       case PIPE_BLENDFACTOR_INV_SRC_COLOR:
 103       case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
 104       case PIPE_BLENDFACTOR_INV_DST_ALPHA:
 105       case PIPE_BLENDFACTOR_INV_DST_COLOR:
 106       case PIPE_BLENDFACTOR_INV_CONST_COLOR:
 107       case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
 108       case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
 109       case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
 110          return true;
 111
 112       default:
 113          return false;
 114    }
 115 }
 116
 117 /* To determine if the destination needs to be read while blending */
 118
 119 static inline bool
 120 util_blend_factor_uses_dest(enum pipe_blendfactor factor, bool alpha)
 121 {
 122    switch (factor) {
 123       case PIPE_BLENDFACTOR_DST_ALPHA:
 124       case PIPE_BLENDFACTOR_DST_COLOR:
 125       case PIPE_BLENDFACTOR_INV_DST_ALPHA:
 126       case PIPE_BLENDFACTOR_INV_DST_COLOR:
 127          return true;
 128       case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
 129          return !alpha;
 130       default:
 131          return false;
 132    }
 133 }
 134
 135 static inline bool
 136 util_blend_uses_dest(struct pipe_rt_blend_state rt)
 137 {
 138    return rt.blend_enable &&
 139       (util_blend_factor_uses_dest(rt.rgb_src_factor, false) ||
 140        util_blend_factor_uses_dest(rt.alpha_src_factor, true) ||
 141        rt.rgb_dst_factor != PIPE_BLENDFACTOR_ZERO ||
 142        rt.alpha_dst_factor != PIPE_BLENDFACTOR_ZERO);
 143 }
 144
 145 #endif /* U_BLEND_H */