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1// Not exposed in shared module
2
3$pure $genIType mix($genIType x, $genIType y, $genBType a);
4$pure $genBType mix($genBType x, $genBType y, $genBType a);
5$pure $genType fma($genType a, $genType b, $genType c);
6$pure $genHType fma($genHType a, $genHType b, $genHType c);
7      $genType frexp($genType x, out $genIType exp);
8      $genHType frexp($genHType x, out $genIType exp);
9$pure $genType ldexp($genType x, in $genIType exp);
10$pure $genHType ldexp($genHType x, in $genIType exp);
11
12$pure uint packSnorm2x16(float2 v);
13$pure uint packUnorm4x8(float4 v);
14$pure uint packSnorm4x8(float4 v);
15$pure float2 unpackSnorm2x16(uint p);
16$pure float4 unpackUnorm4x8(uint p);
17$pure float4 unpackSnorm4x8(uint p);
18$pure uint packHalf2x16(float2 v);
19$pure float2 unpackHalf2x16(uint v);
20
21$pure $genIType bitCount($genIType value);
22$pure $genIType bitCount($genUType value);
23$pure $genIType findLSB($genIType value);
24$pure $genIType findLSB($genUType value);
25$pure $genIType findMSB($genIType value);
26$pure $genIType findMSB($genUType value);
27
28$pure half4 sample(sampler2D s, float2 P);
29$pure half4 sample(sampler2D s, float3 P);
30$pure half4 sample(sampler2D s, float3 P, float bias);
31
32$pure half4 sample(samplerExternalOES s, float2 P);
33$pure half4 sample(samplerExternalOES s, float2 P, float bias);
34
35$pure half4 sample(sampler2DRect s, float2 P);
36$pure half4 sample(sampler2DRect s, float3 P);
37
38$pure half4 sampleLod(sampler2D s, float2 P, float lod);
39$pure half4 sampleLod(sampler2D s, float3 P, float lod);
40
41$pure half4 sampleGrad(sampler2D s, float2, float2 dPdx, float2 dPdy);
42
43// Currently we do not support the generic types of loading subpassInput so we have some explicit
44// versions that we currently use
45$pure half4 subpassLoad(subpassInput subpass);
46$pure half4 subpassLoad(subpassInputMS subpass, int sample);
47
48/** Atomically loads the value from `a` and returns it. */
49$pure uint atomicLoad(atomicUint a);
50
51/** Atomically stores the value of `value` to `a` */
52void atomicStore(atomicUint a, uint value);
53
54/**
55 * Performs an atomic addition of `value` to the contents of `a` and returns the original contents
56 * of `a` from before the addition occurred.
57 */
58uint atomicAdd(atomicUint a, uint value);
59
60// Definitions of functions implementing all of the SkBlendMode blends.
61
62$pure half4 blend_clear(half4 src, half4 dst) { return half4(0); }
63
64$pure half4 blend_src(half4 src, half4 dst) { return src; }
65
66$pure half4 blend_dst(half4 src, half4 dst) { return dst; }
67
68$pure half4 blend_src_over(half4 src, half4 dst) { return src + (1 - src.a)*dst; }
69
70$pure half4 blend_dst_over(half4 src, half4 dst) { return (1 - dst.a)*src + dst; }
71
72$pure half4 blend_src_in(half4 src, half4 dst) { return src*dst.a; }
73
74$pure half4 blend_dst_in(half4 src, half4 dst) { return dst*src.a; }
75
76$pure half4 blend_src_out(half4 src, half4 dst) { return (1 - dst.a)*src; }
77
78$pure half4 blend_dst_out(half4 src, half4 dst) { return (1 - src.a)*dst; }
79
80$pure half4 blend_src_atop(half4 src, half4 dst) { return dst.a*src + (1 - src.a)*dst; }
81
82$pure half4 blend_dst_atop(half4 src, half4 dst)  { return  (1 - dst.a) * src + src.a*dst; }
83
84$pure half4 blend_xor(half4 src, half4 dst) { return (1 - dst.a)*src + (1 - src.a)*dst; }
85
86$pure half4 blend_plus(half4 src, half4 dst) { return min(src + dst, 1); }
87
88// This multi-purpose Porter-Duff blend function can perform any of the thirteen blends above,
89// when passed one of the following values for BlendOp:
90// - Clear:   half4(0, 0,  0,  0)
91// - Src:     half4(1, 0,  0,  0)
92// - Dst:     half4(0, 1,  0,  0)
93// - SrcOver: half4(1, 0,  0, -1)
94// - DstOver: half4(0, 1, -1,  0)
95// - SrcIn:   half4(0, 0,  1,  0)
96// - DstIn:   half4(0, 0,  0,  1)
97// - SrcOut:  half4(0, 0, -1,  0)
98// - DstOut:  half4(0, 0,  0, -1)
99// - SrcATop: half4(0, 0,  1, -1)
100// - DstATop: half4(0, 0, -1,  1)
101// - Xor:     half4(0, 0, -1, -1)
102// - Plus:    half4(1, 1,  0,  0)
103$pure half4 blend_porter_duff(half4 blendOp, half4 src, half4 dst) {
104    half2 coeff = blendOp.xy + (blendOp.zw * (half2(dst.a, src.a) + min(blendOp.zw, 0)));
105    return min(half4(1), src * coeff.x + dst * coeff.y);
106}
107
108$pure half4 blend_modulate(half4 src, half4 dst) { return src*dst; }
109
110$pure half4 blend_screen(half4 src, half4 dst) { return src + (1 - src)*dst; }
111
112$pure half $blend_overlay_component(half2 s, half2 d) {
113    return (2*d.x <= d.y) ? 2*s.x*d.x
114                          : s.y*d.y - 2*(d.y - d.x)*(s.y - s.x);
115}
116
117$pure half4 blend_overlay(half4 src, half4 dst) {
118    half4 result = half4($blend_overlay_component(src.ra, dst.ra),
119                         $blend_overlay_component(src.ga, dst.ga),
120                         $blend_overlay_component(src.ba, dst.ba),
121                         src.a + (1 - src.a)*dst.a);
122    result.rgb += dst.rgb*(1 - src.a) + src.rgb*(1 - dst.a);
123    return result;
124}
125
126$pure half4 blend_overlay(half flip, half4 a, half4 b) {
127    return blend_overlay(bool(flip) ? b : a, bool(flip) ? a : b);
128}
129
130$pure half4 blend_lighten(half4 src, half4 dst) {
131    half4 result = blend_src_over(src, dst);
132    result.rgb = max(result.rgb, (1 - dst.a)*src.rgb + dst.rgb);
133    return result;
134}
135
136$pure half4 blend_darken(half mode /* darken: 1, lighten: -1 */, half4 src, half4 dst) {
137    half4 a = blend_src_over(src, dst);
138    half3 b = (1 - dst.a) * src.rgb + dst.rgb;  // DstOver.rgb
139    a.rgb = mode * min(a.rgb * mode, b.rgb * mode);
140    return a;
141}
142
143$pure half4 blend_darken(half4 src, half4 dst) {
144   return blend_darken(1, src, dst);
145}
146
147const half $kGuardedDivideEpsilon = sk_Caps.mustGuardDivisionEvenAfterExplicitZeroCheck
148                                        ? 0.00000001
149                                        : 0.0;
150
151$pure inline half $guarded_divide(half n, half d) {
152    return n / (d + $kGuardedDivideEpsilon);
153}
154
155$pure inline half3 $guarded_divide(half3 n, half d) {
156    return n / (d + $kGuardedDivideEpsilon);
157}
158
159$pure half $color_dodge_component(half2 s, half2 d) {
160    if (d.x == 0) {
161        return s.x*(1 - d.y);
162    } else {
163        half delta = s.y - s.x;
164        if (delta == 0) {
165            return s.y*d.y + s.x*(1 - d.y) + d.x*(1 - s.y);
166        } else {
167            delta = min(d.y, $guarded_divide(d.x*s.y, delta));
168            return delta*s.y + s.x*(1 - d.y) + d.x*(1 - s.y);
169        }
170    }
171}
172
173$pure half4 blend_color_dodge(half4 src, half4 dst) {
174    return half4($color_dodge_component(src.ra, dst.ra),
175                 $color_dodge_component(src.ga, dst.ga),
176                 $color_dodge_component(src.ba, dst.ba),
177                 src.a + (1 - src.a)*dst.a);
178}
179
180$pure half $color_burn_component(half2 s, half2 d) {
181    if (d.y == d.x) {
182        return s.y*d.y + s.x*(1 - d.y) + d.x*(1 - s.y);
183    } else if (s.x == 0) {
184        return d.x*(1 - s.y);
185    } else {
186        half delta = max(0, d.y - $guarded_divide((d.y - d.x)*s.y, s.x));
187        return delta*s.y + s.x*(1 - d.y) + d.x*(1 - s.y);
188    }
189}
190
191$pure half4 blend_color_burn(half4 src, half4 dst) {
192    return half4($color_burn_component(src.ra, dst.ra),
193                 $color_burn_component(src.ga, dst.ga),
194                 $color_burn_component(src.ba, dst.ba),
195                 src.a + (1 - src.a)*dst.a);
196}
197
198$pure half4 blend_hard_light(half4 src, half4 dst) {
199    return blend_overlay(dst, src);
200}
201
202$pure half $soft_light_component(half2 s, half2 d) {
203    if (2*s.x <= s.y) {
204        return $guarded_divide(d.x*d.x*(s.y - 2*s.x), d.y) + (1 - d.y)*s.x + d.x*(-s.y + 2*s.x + 1);
205    } else if (4.0 * d.x <= d.y) {
206        half DSqd = d.x*d.x;
207        half DCub = DSqd*d.x;
208        half DaSqd = d.y*d.y;
209        half DaCub = DaSqd*d.y;
210        return $guarded_divide(DaSqd*(s.x - d.x*(3*s.y - 6*s.x - 1)) + 12*d.y*DSqd*(s.y - 2*s.x)
211                               - 16*DCub * (s.y - 2*s.x) - DaCub*s.x, DaSqd);
212    } else {
213        return d.x*(s.y - 2*s.x + 1) + s.x - sqrt(d.y*d.x)*(s.y - 2*s.x) - d.y*s.x;
214    }
215}
216
217$pure half4 blend_soft_light(half4 src, half4 dst) {
218    return (dst.a == 0) ? src : half4($soft_light_component(src.ra, dst.ra),
219                                      $soft_light_component(src.ga, dst.ga),
220                                      $soft_light_component(src.ba, dst.ba),
221                                      src.a + (1 - src.a)*dst.a);
222}
223
224$pure half4 blend_difference(half4 src, half4 dst) {
225    return half4(src.rgb + dst.rgb - 2*min(src.rgb*dst.a, dst.rgb*src.a),
226                 src.a + (1 - src.a)*dst.a);
227}
228
229$pure half4 blend_exclusion(half4 src, half4 dst) {
230    return half4(dst.rgb + src.rgb - 2*dst.rgb*src.rgb, src.a + (1 - src.a)*dst.a);
231}
232
233$pure half4 blend_multiply(half4 src, half4 dst) {
234    return half4((1 - src.a)*dst.rgb + (1 - dst.a)*src.rgb + src.rgb*dst.rgb,
235                 src.a + (1 - src.a)*dst.a);
236}
237
238$pure half $blend_color_luminance(half3 color) { return dot(half3(0.3, 0.59, 0.11), color); }
239
240$pure half3 $blend_set_color_luminance(half3 hueSatColor, half alpha, half3 lumColor) {
241    half lum = $blend_color_luminance(lumColor);
242    half3 result = lum - $blend_color_luminance(hueSatColor) + hueSatColor;
243    half minComp = min(min(result.r, result.g), result.b);
244    half maxComp = max(max(result.r, result.g), result.b);
245    if (minComp < 0 && lum != minComp) {
246        result = lum + (result - lum) * $guarded_divide(lum, (lum - minComp));
247    }
248    if (maxComp > alpha && maxComp != lum) {
249        result = lum + $guarded_divide((result - lum) * (alpha - lum), (maxComp - lum));
250    }
251    return result;
252}
253
254$pure half $blend_color_saturation(half3 color) {
255    return max(max(color.r, color.g), color.b) - min(min(color.r, color.g), color.b);
256}
257
258$pure half3 $blend_set_color_saturation(half3 color, half3 satColor) {
259    half mn = min(min(color.r, color.g), color.b);
260    half mx = max(max(color.r, color.g), color.b);
261
262    return (mx > mn) ? ((color - mn) * $blend_color_saturation(satColor)) / (mx - mn)
263                     : half3(0);
264}
265
266$pure half4 blend_hslc(half2 flipSat, half4 src, half4 dst) {
267    half alpha = dst.a * src.a;
268    half3 sda = src.rgb * dst.a;
269    half3 dsa = dst.rgb * src.a;
270    half3 l = bool(flipSat.x) ? dsa : sda;
271    half3 r = bool(flipSat.x) ? sda : dsa;
272    if (bool(flipSat.y)) {
273        l = $blend_set_color_saturation(l, r);
274        r = dsa;
275    }
276    return half4($blend_set_color_luminance(l, alpha, r) + dst.rgb - dsa + src.rgb - sda,
277                 src.a + dst.a - alpha);
278}
279
280$pure half4 blend_hue(half4 src, half4 dst) {
281    return blend_hslc(half2(0, 1), src, dst);
282}
283
284$pure half4 blend_saturation(half4 src, half4 dst) {
285    return blend_hslc(half2(1), src, dst);
286}
287
288$pure half4 blend_color(half4 src, half4 dst)  {
289    return blend_hslc(half2(0), src, dst);
290}
291
292$pure half4 blend_luminosity(half4 src, half4 dst) {
293    return blend_hslc(half2(1, 0), src, dst);
294}
295
296$pure float2 proj(float3 p) { return p.xy / p.z; }
297
298// Implement cross() as a determinant to communicate our intent more clearly to the compiler.
299// NOTE: Due to precision issues, it might be the case that cross(a, a) != 0.
300$pure float cross_length_2d(float2 a, float2 b) {
301    return determinant(float2x2(a, b));
302}
303
304$pure half cross_length_2d(half2 a, half2 b) {
305    return determinant(half2x2(a, b));
306}
307
308$pure float2 perp(float2 v) {
309    return float2(-v.y, v.x);
310}
311
312$pure half2 perp(half2 v) {
313    return half2(-v.y, v.x);
314}
315
316// Returns a bias given a scale factor, such that 'scale * (dist + bias)' converts the distance to
317// a per-pixel coverage value, automatically widening the visible coverage ramp for subpixel
318// dimensions. The 'scale' must already be equal to the narrowest dimension of the shape and clamped
319// to [0, 1.0].
320$pure float coverage_bias(float scale) {
321    return 1.0 - 0.5 * scale;
322}
323