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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
util_blend_dst_alpha_to_one(int factor)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
util_blend_func_to_shader(enum pipe_blend_func 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
util_blend_factor_to_shader(enum pipe_blendfactor 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
util_blend_factor_is_inverted(enum pipe_blendfactor factor)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
util_blend_factor_uses_dest(enum pipe_blendfactor factor,bool alpha)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
util_blend_uses_dest(struct pipe_rt_blend_state rt)136 util_blend_uses_dest(struct pipe_rt_blend_state rt)
137 {
138    return rt.blend_enable &&
139       (util_blend_factor_uses_dest((enum pipe_blendfactor)rt.rgb_src_factor, false) ||
140        util_blend_factor_uses_dest((enum pipe_blendfactor)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 */
146