1 /*
2 * Copyright 2014 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "GrCoordTransform.h"
9 #include "GrCaps.h"
10 #include "GrContext.h"
11 #include "GrGpu.h"
12
reset(GrCoordSet sourceCoords,const SkMatrix & m,const GrTexture * texture,GrTextureParams::FilterMode filter)13 void GrCoordTransform::reset(GrCoordSet sourceCoords, const SkMatrix& m, const GrTexture* texture,
14 GrTextureParams::FilterMode filter) {
15 SkASSERT(texture);
16 SkASSERT(!fInProcessor);
17
18 fSourceCoords = sourceCoords;
19 fMatrix = m;
20 fReverseY = kBottomLeft_GrSurfaceOrigin == texture->origin();
21
22 // Always start at kDefault. Then if precisions differ we see if the precision needs to be
23 // increased. Our rule is that we want at least 4 subpixel values in the representation for
24 // coords between 0 to 1 when bi- or tri-lerping and 1 value when nearest filtering. Note that
25 // this still might not be enough when drawing with repeat or mirror-repeat modes but that case
26 // can be arbitrarily bad.
27 int subPixelThresh = filter > GrTextureParams::kNone_FilterMode ? 4 : 1;
28 fPrecision = kDefault_GrSLPrecision;
29 if (texture->getContext()) {
30 const GrShaderCaps* caps = texture->getContext()->caps()->shaderCaps();
31 if (caps->floatPrecisionVaries()) {
32 int maxD = SkTMax(texture->width(), texture->height());
33 const GrShaderCaps::PrecisionInfo* info;
34 info = &caps->getFloatShaderPrecisionInfo(kFragment_GrShaderType, fPrecision);
35 do {
36 SkASSERT(info->supported());
37 // Make sure there is at least 2 bits of subpixel precision in the range of
38 // texture coords from 0.5 to 1.0.
39 if ((2 << info->fBits) / maxD > subPixelThresh) {
40 break;
41 }
42 if (kHigh_GrSLPrecision == fPrecision) {
43 break;
44 }
45 GrSLPrecision nextP = static_cast<GrSLPrecision>(fPrecision + 1);
46 info = &caps->getFloatShaderPrecisionInfo(kFragment_GrShaderType, nextP);
47 if (!info->supported()) {
48 break;
49 }
50 fPrecision = nextP;
51 } while (true);
52 }
53 }
54 }
55
reset(GrCoordSet sourceCoords,const SkMatrix & m,GrSLPrecision precision)56 void GrCoordTransform::reset(GrCoordSet sourceCoords,
57 const SkMatrix& m,
58 GrSLPrecision precision) {
59 SkASSERT(!fInProcessor);
60 fSourceCoords = sourceCoords;
61 fMatrix = m;
62 fReverseY = false;
63 fPrecision = precision;
64 }
65