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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "GrCoordTransform.h"
#include "GrCaps.h"
#include "GrContext.h"
#include "GrGpu.h"
#include "GrTextureProxy.h"
static GrSLPrecision compute_precision(const GrShaderCaps* caps,
int width, int height,
GrSamplerParams::FilterMode filter) {
// Always start at kDefault. Then if precisions differ we see if the precision needs to be
// increased. Our rule is that we want at least 4 subpixel values in the representation for
// coords between 0 to 1 when bi- or tri-lerping and 1 value when nearest filtering. Note that
// this still might not be enough when drawing with repeat or mirror-repeat modes but that case
// can be arbitrarily bad.
int subPixelThresh = filter > GrSamplerParams::kNone_FilterMode ? 4 : 1;
GrSLPrecision precision = kDefault_GrSLPrecision;
if (caps) {
if (caps->floatPrecisionVaries()) {
int maxD = SkTMax(width, height);
const GrShaderCaps::PrecisionInfo* info;
info = &caps->getFloatShaderPrecisionInfo(kFragment_GrShaderType, precision);
do {
SkASSERT(info->supported());
// Make sure there is at least 2 bits of subpixel precision in the range of
// texture coords from 0.5 to 1.0.
if ((2 << info->fBits) / maxD > subPixelThresh) {
break;
}
if (kHigh_GrSLPrecision == precision) {
break;
}
GrSLPrecision nextP = static_cast<GrSLPrecision>(precision + 1);
info = &caps->getFloatShaderPrecisionInfo(kFragment_GrShaderType, nextP);
if (!info->supported()) {
break;
}
precision = nextP;
} while (true);
}
}
return precision;
}
void GrCoordTransform::reset(const SkMatrix& m, const GrTexture* texture,
GrSamplerParams::FilterMode filter, bool normalize) {
SkASSERT(texture);
SkASSERT(!fInProcessor);
fMatrix = m;
fTexture = texture;
fNormalize = normalize;
fReverseY = kBottomLeft_GrSurfaceOrigin == texture->origin();
if (texture->getContext()) {
fPrecision = compute_precision(texture->getContext()->caps()->shaderCaps(),
texture->width(), texture->height(), filter);
} else {
fPrecision = kDefault_GrSLPrecision;
}
}
void GrCoordTransform::reset(GrContext* context, const SkMatrix& m,
GrTextureProxy* proxy,
GrSamplerParams::FilterMode filter, bool normalize) {
SkASSERT(proxy);
SkASSERT(!fInProcessor);
fMatrix = m;
// MDB TODO: just GrCaps is needed for this method
// MDB TODO: once all the coord transforms take a proxy just store it here and
// instantiate later
fTexture = proxy->instantiate(context->textureProvider());
fNormalize = normalize;
fReverseY = kBottomLeft_GrSurfaceOrigin == proxy->origin();
const GrCaps* caps = context->caps();
fPrecision = compute_precision(caps->shaderCaps(),
proxy->worstCaseWidth(*caps),
proxy->worstCaseHeight(*caps), filter);
}
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