blob: 192f47d6213e37d9b8acbb39e12a8fcda33319ba [file] [log] [blame]
/*
* Copyright 2020 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "gm/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkData.h"
#include "include/core/SkPaint.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkSurface.h"
#include "include/effects/SkRuntimeEffect.h"
#include "tools/Resources.h"
class KawaseBlurFilter {
public:
// Downsample scale factor used to improve performance
static constexpr float kInputScale = 0.25f;
// Downsample scale factor used to improve performance
static constexpr float kInverseInputScale = 1.0f / kInputScale;
// Maximum number of render passes
static constexpr uint32_t kMaxPasses = 4;
// To avoid downscaling artifacts, we interpolate the blurred fbo with the full composited
// image, up to this radius.
static constexpr float kMaxCrossFadeRadius = 30.0f;
KawaseBlurFilter() {
SkString blurString(R"(
uniform shader src;
uniform float in_inverseScale;
uniform float2 in_blurOffset;
half4 main(float2 xy) {
float2 scaled_xy = float2(xy.x * in_inverseScale, xy.y * in_inverseScale);
half4 c = src.eval(scaled_xy);
c += src.eval(scaled_xy + float2( in_blurOffset.x, in_blurOffset.y));
c += src.eval(scaled_xy + float2( in_blurOffset.x, -in_blurOffset.y));
c += src.eval(scaled_xy + float2(-in_blurOffset.x, in_blurOffset.y));
c += src.eval(scaled_xy + float2(-in_blurOffset.x, -in_blurOffset.y));
return half4(c.rgb * 0.2, 1.0);
}
)");
SkString mixString(R"(
uniform shader in_blur;
uniform shader in_original;
uniform float in_inverseScale;
uniform float in_mix;
half4 main(float2 xy) {
float2 scaled_xy = float2(xy.x * in_inverseScale, xy.y * in_inverseScale);
half4 blurred = in_blur.eval(scaled_xy);
half4 composition = in_original.eval(xy);
return mix(composition, blurred, in_mix);
}
)");
auto [blurEffect, error] = SkRuntimeEffect::MakeForShader(blurString);
if (!blurEffect) {
SkDEBUGFAILF("RuntimeShader error: %s\n", error.c_str());
}
fBlurEffect = std::move(blurEffect);
auto [mixEffect, error2] = SkRuntimeEffect::MakeForShader(mixString);
if (!mixEffect) {
SkDEBUGFAILF("RuntimeShader error: %s\n", error2.c_str());
}
fMixEffect = std::move(mixEffect);
}
static sk_sp<SkSurface> MakeSurface(SkCanvas* canvas, const SkImageInfo& info) {
if (sk_sp<SkSurface> surface = canvas->makeSurface(info)) {
return surface;
}
// serialize-8888 returns null from makeSurface; fallback to a raster surface.
return SkSurfaces::Raster(info);
}
void draw(SkCanvas* canvas, sk_sp<SkImage> input, int blurRadius) {
// NOTE: this is only experimental and the current blur params cause points to be sampled
// beyond the input blur radius.
// Kawase is an approximation of Gaussian, but it behaves differently from it.
// A radius transformation is required for approximating them, and also to introduce
// non-integer steps, necessary to smoothly interpolate large radii.
float tmpRadius = (float)blurRadius / 6.0f;
float numberOfPasses = std::min(kMaxPasses, (uint32_t)ceil(tmpRadius));
float radiusByPasses = tmpRadius / (float)numberOfPasses;
SkImageInfo scaledInfo = SkImageInfo::MakeN32Premul((float)input->width() * kInputScale,
(float)input->height() * kInputScale);
auto drawSurface = MakeSurface(canvas, scaledInfo);
const float stepX = radiusByPasses;
const float stepY = radiusByPasses;
// start by drawing and downscaling and doing the first blur pass
SkRuntimeShaderBuilder blurBuilder(fBlurEffect);
blurBuilder.child("src") = input->makeShader(SkSamplingOptions(SkFilterMode::kLinear));
blurBuilder.uniform("in_inverseScale") = kInverseInputScale;
blurBuilder.uniform("in_blurOffset") = SkV2{stepX * kInverseInputScale,
stepY * kInverseInputScale};
SkPaint paint;
paint.setShader(blurBuilder.makeShader());
drawSurface->getCanvas()->drawIRect(scaledInfo.bounds(), paint);
// DEBUG draw each of the stages
canvas->save();
canvas->drawImage(drawSurface->makeImageSnapshot(), input->width() / 4, 0,
SkSamplingOptions());
canvas->translate(input->width() / 4, input->height() * 0.75);
// And now we'll ping pong between our surfaces, to accumulate the result of various
// offsets.
auto lastDrawTarget = drawSurface;
if (numberOfPasses > 1) {
auto readSurface = drawSurface;
drawSurface = MakeSurface(canvas, scaledInfo);
for (auto i = 1; i < numberOfPasses; i++) {
const float stepScale = (float)i * kInputScale;
blurBuilder.child("src") = readSurface->makeImageSnapshot()->makeShader(
SkSamplingOptions(SkFilterMode::kLinear));
blurBuilder.uniform("in_inverseScale") = 1.0f;
blurBuilder.uniform("in_blurOffset") = SkV2{stepX * stepScale , stepY * stepScale};
paint.setShader(blurBuilder.makeShader());
drawSurface->getCanvas()->drawIRect(scaledInfo.bounds(), paint);
// DEBUG draw each of the stages
canvas->drawImage(drawSurface->makeImageSnapshot(), 0, 0, SkSamplingOptions());
canvas->translate(0, input->height() * 0.75);
// Swap buffers for next iteration
auto tmp = drawSurface;
drawSurface = readSurface;
readSurface = tmp;
}
lastDrawTarget = readSurface;
}
// restore translations done for debug and offset
canvas->restore();
SkAutoCanvasRestore acr(canvas, true);
canvas->translate(input->width(), 0);
// do the final composition and when we scale our blur up. It will be interpolated
// with the larger composited texture to hide downscaling artifacts.
SkRuntimeShaderBuilder mixBuilder(fMixEffect);
mixBuilder.child("in_blur") = lastDrawTarget->makeImageSnapshot()->makeShader(
SkSamplingOptions(SkFilterMode::kLinear));
mixBuilder.child("in_original") =
input->makeShader(SkSamplingOptions(SkFilterMode::kLinear));
mixBuilder.uniform("in_inverseScale") = kInputScale;
mixBuilder.uniform("in_mix") = std::min(1.0f, (float)blurRadius / kMaxCrossFadeRadius);
paint.setShader(mixBuilder.makeShader());
canvas->drawIRect(input->bounds(), paint);
}
private:
sk_sp<SkRuntimeEffect> fBlurEffect;
sk_sp<SkRuntimeEffect> fMixEffect;
};
class KawaseBlurRT : public skiagm::GM {
public:
KawaseBlurRT() {}
SkString onShortName() override { return SkString("kawase_blur_rt"); }
SkISize onISize() override { return {1280, 768}; }
void onOnceBeforeDraw() override {
fMandrill = GetResourceAsImage("images/mandrill_256.png");
}
void onDraw(SkCanvas* canvas) override {
canvas->drawImage(fMandrill, 0, 0);
canvas->translate(256, 0);
KawaseBlurFilter blurFilter;
blurFilter.draw(canvas, fMandrill, 45);
canvas->translate(512, 0);
blurFilter.draw(canvas, fMandrill, 55);
}
private:
sk_sp<SkImage> fMandrill;
};
DEF_GM(return new KawaseBlurRT;)