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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/common/gpu/client/gl_helper_scaling.h"
#include <deque>
#include <string>
#include <vector>
#include "base/bind.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/message_loop/message_loop.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "gpu/command_buffer/client/gles2_interface.h"
#include "third_party/skia/include/core/SkRegion.h"
#include "ui/gfx/geometry/rect.h"
#include "ui/gfx/geometry/size.h"
using gpu::gles2::GLES2Interface;
namespace content {
GLHelperScaling::GLHelperScaling(GLES2Interface* gl, GLHelper* helper)
: gl_(gl), helper_(helper), vertex_attributes_buffer_(gl_) {
InitBuffer();
}
GLHelperScaling::~GLHelperScaling() {}
// Used to keep track of a generated shader program. The program
// is passed in as text through Setup and is used by calling
// UseProgram() with the right parameters. Note that |gl_|
// and |helper_| are assumed to live longer than this program.
class ShaderProgram : public base::RefCounted<ShaderProgram> {
public:
ShaderProgram(GLES2Interface* gl, GLHelper* helper)
: gl_(gl),
helper_(helper),
program_(gl_->CreateProgram()),
position_location_(-1),
texcoord_location_(-1),
src_subrect_location_(-1),
src_pixelsize_location_(-1),
dst_pixelsize_location_(-1),
scaling_vector_location_(-1),
color_weights_location_(-1) {}
// Compile shader program.
void Setup(const GLchar* vertex_shader_text,
const GLchar* fragment_shader_text);
// UseProgram must be called with GL_TEXTURE_2D bound to the
// source texture and GL_ARRAY_BUFFER bound to a vertex
// attribute buffer.
void UseProgram(const gfx::Size& src_size,
const gfx::Rect& src_subrect,
const gfx::Size& dst_size,
bool scale_x,
bool flip_y,
GLfloat color_weights[4]);
bool Initialized() const { return position_location_ != -1; }
private:
friend class base::RefCounted<ShaderProgram>;
~ShaderProgram() { gl_->DeleteProgram(program_); }
GLES2Interface* gl_;
GLHelper* helper_;
// A program for copying a source texture into a destination texture.
GLuint program_;
// The location of the position in the program.
GLint position_location_;
// The location of the texture coordinate in the program.
GLint texcoord_location_;
// The location of the source texture in the program.
GLint texture_location_;
// The location of the texture coordinate of
// the sub-rectangle in the program.
GLint src_subrect_location_;
// Location of size of source image in pixels.
GLint src_pixelsize_location_;
// Location of size of destination image in pixels.
GLint dst_pixelsize_location_;
// Location of vector for scaling direction.
GLint scaling_vector_location_;
// Location of color weights.
GLint color_weights_location_;
DISALLOW_COPY_AND_ASSIGN(ShaderProgram);
};
// Implementation of a single stage in a scaler pipeline. If the pipeline has
// multiple stages, it calls Scale() on the subscaler, then further scales the
// output. Caches textures and framebuffers to avoid allocating/deleting
// them once per frame, which can be expensive on some drivers.
class ScalerImpl : public GLHelper::ScalerInterface,
public GLHelperScaling::ShaderInterface {
public:
// |gl| and |copy_impl| are expected to live longer than this object.
// |src_size| is the size of the input texture in pixels.
// |dst_size| is the size of the output texutre in pixels.
// |src_subrect| is the portion of the src to copy to the output texture.
// If |scale_x| is true, we are scaling along the X axis, otherwise Y.
// If we are scaling in both X and Y, |scale_x| is ignored.
// If |vertically_flip_texture| is true, output will be upside-down.
// If |swizzle| is true, RGBA will be transformed into BGRA.
// |color_weights| are only used together with SHADER_PLANAR to specify
// how to convert RGB colors into a single value.
ScalerImpl(GLES2Interface* gl,
GLHelperScaling* scaler_helper,
const GLHelperScaling::ScalerStage& scaler_stage,
ScalerImpl* subscaler,
const float* color_weights)
: gl_(gl),
scaler_helper_(scaler_helper),
spec_(scaler_stage),
intermediate_texture_(0),
dst_framebuffer_(gl),
subscaler_(subscaler) {
if (color_weights) {
color_weights_[0] = color_weights[0];
color_weights_[1] = color_weights[1];
color_weights_[2] = color_weights[2];
color_weights_[3] = color_weights[3];
} else {
color_weights_[0] = 0.0;
color_weights_[1] = 0.0;
color_weights_[2] = 0.0;
color_weights_[3] = 0.0;
}
shader_program_ =
scaler_helper_->GetShaderProgram(spec_.shader, spec_.swizzle);
if (subscaler_) {
intermediate_texture_ = 0u;
gl_->GenTextures(1, &intermediate_texture_);
ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_,
intermediate_texture_);
gl_->TexImage2D(GL_TEXTURE_2D,
0,
GL_RGBA,
spec_.src_size.width(),
spec_.src_size.height(),
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
NULL);
}
}
~ScalerImpl() override {
if (intermediate_texture_) {
gl_->DeleteTextures(1, &intermediate_texture_);
}
}
// GLHelperShader::ShaderInterface implementation.
void Execute(GLuint source_texture,
const std::vector<GLuint>& dest_textures) override {
if (subscaler_) {
subscaler_->Scale(source_texture, intermediate_texture_);
source_texture = intermediate_texture_;
}
ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(
gl_, dst_framebuffer_);
DCHECK_GT(dest_textures.size(), 0U);
scoped_ptr<GLenum[]> buffers(new GLenum[dest_textures.size()]);
for (size_t t = 0; t < dest_textures.size(); t++) {
ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, dest_textures[t]);
gl_->FramebufferTexture2D(GL_FRAMEBUFFER,
GL_COLOR_ATTACHMENT0 + t,
GL_TEXTURE_2D,
dest_textures[t],
0);
buffers[t] = GL_COLOR_ATTACHMENT0 + t;
}
ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, source_texture);
gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
ScopedBufferBinder<GL_ARRAY_BUFFER> buffer_binder(
gl_, scaler_helper_->vertex_attributes_buffer_);
DCHECK(shader_program_->Initialized());
shader_program_->UseProgram(spec_.src_size,
spec_.src_subrect,
spec_.dst_size,
spec_.scale_x,
spec_.vertically_flip_texture,
color_weights_);
gl_->Viewport(0, 0, spec_.dst_size.width(), spec_.dst_size.height());
if (dest_textures.size() > 1) {
DCHECK_LE(static_cast<int>(dest_textures.size()),
scaler_helper_->helper_->MaxDrawBuffers());
gl_->DrawBuffersEXT(dest_textures.size(), buffers.get());
}
// Conduct texture mapping by drawing a quad composed of two triangles.
gl_->DrawArrays(GL_TRIANGLE_STRIP, 0, 4);
if (dest_textures.size() > 1) {
// Set the draw buffers back to not confuse others.
gl_->DrawBuffersEXT(1, &buffers[0]);
}
}
// GLHelper::ScalerInterface implementation.
void Scale(GLuint source_texture, GLuint dest_texture) override {
std::vector<GLuint> tmp(1);
tmp[0] = dest_texture;
Execute(source_texture, tmp);
}
const gfx::Size& SrcSize() override {
if (subscaler_) {
return subscaler_->SrcSize();
}
return spec_.src_size;
}
const gfx::Rect& SrcSubrect() override {
if (subscaler_) {
return subscaler_->SrcSubrect();
}
return spec_.src_subrect;
}
const gfx::Size& DstSize() override { return spec_.dst_size; }
private:
GLES2Interface* gl_;
GLHelperScaling* scaler_helper_;
GLHelperScaling::ScalerStage spec_;
GLfloat color_weights_[4];
GLuint intermediate_texture_;
scoped_refptr<ShaderProgram> shader_program_;
ScopedFramebuffer dst_framebuffer_;
scoped_ptr<ScalerImpl> subscaler_;
};
GLHelperScaling::ScalerStage::ScalerStage(ShaderType shader_,
gfx::Size src_size_,
gfx::Rect src_subrect_,
gfx::Size dst_size_,
bool scale_x_,
bool vertically_flip_texture_,
bool swizzle_)
: shader(shader_),
src_size(src_size_),
src_subrect(src_subrect_),
dst_size(dst_size_),
scale_x(scale_x_),
vertically_flip_texture(vertically_flip_texture_),
swizzle(swizzle_) {}
// The important inputs for this function is |x_ops| and
// |y_ops|. They represent scaling operations to be done
// on an imag of size |src_size|. If |quality| is SCALER_QUALITY_BEST,
// then we will interpret these scale operations literally and we'll
// create one scaler stage for each ScaleOp. However, if |quality|
// is SCALER_QUALITY_GOOD, then we can do a whole bunch of optimizations
// by combining two or more ScaleOps in to a single scaler stage.
// Normally we process ScaleOps from |y_ops| first and |x_ops| after
// all |y_ops| are processed, but sometimes we can combine one or more
// operation from both queues essentially for free. This is the reason
// why |x_ops| and |y_ops| aren't just one single queue.
void GLHelperScaling::ConvertScalerOpsToScalerStages(
GLHelper::ScalerQuality quality,
gfx::Size src_size,
gfx::Rect src_subrect,
const gfx::Size& dst_size,
bool vertically_flip_texture,
bool swizzle,
std::deque<GLHelperScaling::ScaleOp>* x_ops,
std::deque<GLHelperScaling::ScaleOp>* y_ops,
std::vector<ScalerStage>* scaler_stages) {
while (!x_ops->empty() || !y_ops->empty()) {
gfx::Size intermediate_size = src_subrect.size();
std::deque<ScaleOp>* current_queue = NULL;
if (!y_ops->empty()) {
current_queue = y_ops;
} else {
current_queue = x_ops;
}
ShaderType current_shader = SHADER_BILINEAR;
switch (current_queue->front().scale_factor) {
case 0:
if (quality == GLHelper::SCALER_QUALITY_BEST) {
current_shader = SHADER_BICUBIC_UPSCALE;
}
break;
case 2:
if (quality == GLHelper::SCALER_QUALITY_BEST) {
current_shader = SHADER_BICUBIC_HALF_1D;
}
break;
case 3:
DCHECK(quality != GLHelper::SCALER_QUALITY_BEST);
current_shader = SHADER_BILINEAR3;
break;
default:
NOTREACHED();
}
bool scale_x = current_queue->front().scale_x;
current_queue->front().UpdateSize(&intermediate_size);
current_queue->pop_front();
// Optimization: Sometimes we can combine 2-4 scaling operations into
// one operation.
if (quality == GLHelper::SCALER_QUALITY_GOOD) {
if (!current_queue->empty() && current_shader == SHADER_BILINEAR) {
// Combine two steps in the same dimension.
current_queue->front().UpdateSize(&intermediate_size);
current_queue->pop_front();
current_shader = SHADER_BILINEAR2;
if (!current_queue->empty()) {
// Combine three steps in the same dimension.
current_queue->front().UpdateSize(&intermediate_size);
current_queue->pop_front();
current_shader = SHADER_BILINEAR4;
}
}
// Check if we can combine some steps in the other dimension as well.
// Since all shaders currently use GL_LINEAR, we can easily scale up
// or scale down by exactly 2x at the same time as we do another
// operation. Currently, the following mergers are supported:
// * 1 bilinear Y-pass with 1 bilinear X-pass (up or down)
// * 2 bilinear Y-passes with 2 bilinear X-passes
// * 1 bilinear Y-pass with N bilinear X-pass
// * N bilinear Y-passes with 1 bilinear X-pass (down only)
// Measurements indicate that generalizing this for 3x3 and 4x4
// makes it slower on some platforms, such as the Pixel.
if (!scale_x && x_ops->size() > 0 && x_ops->front().scale_factor <= 2) {
int x_passes = 0;
if (current_shader == SHADER_BILINEAR2 && x_ops->size() >= 2) {
// 2y + 2x passes
x_passes = 2;
current_shader = SHADER_BILINEAR2X2;
} else if (current_shader == SHADER_BILINEAR) {
// 1y + Nx passes
scale_x = true;
switch (x_ops->size()) {
case 0:
NOTREACHED();
case 1:
if (x_ops->front().scale_factor == 3) {
current_shader = SHADER_BILINEAR3;
}
x_passes = 1;
break;
case 2:
x_passes = 2;
current_shader = SHADER_BILINEAR2;
break;
default:
x_passes = 3;
current_shader = SHADER_BILINEAR4;
break;
}
} else if (x_ops->front().scale_factor == 2) {
// Ny + 1x-downscale
x_passes = 1;
}
for (int i = 0; i < x_passes; i++) {
x_ops->front().UpdateSize(&intermediate_size);
x_ops->pop_front();
}
}
}
scaler_stages->push_back(ScalerStage(current_shader,
src_size,
src_subrect,
intermediate_size,
scale_x,
vertically_flip_texture,
swizzle));
src_size = intermediate_size;
src_subrect = gfx::Rect(intermediate_size);
vertically_flip_texture = false;
swizzle = false;
}
}
void GLHelperScaling::ComputeScalerStages(
GLHelper::ScalerQuality quality,
const gfx::Size& src_size,
const gfx::Rect& src_subrect,
const gfx::Size& dst_size,
bool vertically_flip_texture,
bool swizzle,
std::vector<ScalerStage>* scaler_stages) {
if (quality == GLHelper::SCALER_QUALITY_FAST ||
src_subrect.size() == dst_size) {
scaler_stages->push_back(ScalerStage(SHADER_BILINEAR,
src_size,
src_subrect,
dst_size,
false,
vertically_flip_texture,
swizzle));
return;
}
std::deque<GLHelperScaling::ScaleOp> x_ops, y_ops;
GLHelperScaling::ScaleOp::AddOps(src_subrect.width(),
dst_size.width(),
true,
quality == GLHelper::SCALER_QUALITY_GOOD,
&x_ops);
GLHelperScaling::ScaleOp::AddOps(src_subrect.height(),
dst_size.height(),
false,
quality == GLHelper::SCALER_QUALITY_GOOD,
&y_ops);
ConvertScalerOpsToScalerStages(quality,
src_size,
src_subrect,
dst_size,
vertically_flip_texture,
swizzle,
&x_ops,
&y_ops,
scaler_stages);
}
GLHelper::ScalerInterface* GLHelperScaling::CreateScaler(
GLHelper::ScalerQuality quality,
gfx::Size src_size,
gfx::Rect src_subrect,
const gfx::Size& dst_size,
bool vertically_flip_texture,
bool swizzle) {
std::vector<ScalerStage> scaler_stages;
ComputeScalerStages(quality,
src_size,
src_subrect,
dst_size,
vertically_flip_texture,
swizzle,
&scaler_stages);
ScalerImpl* ret = NULL;
for (unsigned int i = 0; i < scaler_stages.size(); i++) {
ret = new ScalerImpl(gl_, this, scaler_stages[i], ret, NULL);
}
return ret;
}
GLHelper::ScalerInterface* GLHelperScaling::CreatePlanarScaler(
const gfx::Size& src_size,
const gfx::Rect& src_subrect,
const gfx::Size& dst_size,
bool vertically_flip_texture,
bool swizzle,
const float color_weights[4]) {
ScalerStage stage(SHADER_PLANAR,
src_size,
src_subrect,
dst_size,
true,
vertically_flip_texture,
swizzle);
return new ScalerImpl(gl_, this, stage, NULL, color_weights);
}
GLHelperScaling::ShaderInterface* GLHelperScaling::CreateYuvMrtShader(
const gfx::Size& src_size,
const gfx::Rect& src_subrect,
const gfx::Size& dst_size,
bool vertically_flip_texture,
bool swizzle,
ShaderType shader) {
DCHECK(shader == SHADER_YUV_MRT_PASS1 || shader == SHADER_YUV_MRT_PASS2);
ScalerStage stage(shader,
src_size,
src_subrect,
dst_size,
true,
vertically_flip_texture,
swizzle);
return new ScalerImpl(gl_, this, stage, NULL, NULL);
}
const GLfloat GLHelperScaling::kVertexAttributes[] = {
-1.0f, -1.0f, 0.0f, 0.0f, // vertex 0
1.0f, -1.0f, 1.0f, 0.0f, // vertex 1
-1.0f, 1.0f, 0.0f, 1.0f, // vertex 2
1.0f, 1.0f, 1.0f, 1.0f, }; // vertex 3
void GLHelperScaling::InitBuffer() {
ScopedBufferBinder<GL_ARRAY_BUFFER> buffer_binder(gl_,
vertex_attributes_buffer_);
gl_->BufferData(GL_ARRAY_BUFFER,
sizeof(kVertexAttributes),
kVertexAttributes,
GL_STATIC_DRAW);
}
scoped_refptr<ShaderProgram> GLHelperScaling::GetShaderProgram(ShaderType type,
bool swizzle) {
ShaderProgramKeyType key(type, swizzle);
scoped_refptr<ShaderProgram>& cache_entry(shader_programs_[key]);
if (!cache_entry.get()) {
cache_entry = new ShaderProgram(gl_, helper_);
std::basic_string<GLchar> vertex_program;
std::basic_string<GLchar> fragment_program;
std::basic_string<GLchar> vertex_header;
std::basic_string<GLchar> fragment_directives;
std::basic_string<GLchar> fragment_header;
std::basic_string<GLchar> shared_variables;
vertex_header.append(
"precision highp float;\n"
"attribute vec2 a_position;\n"
"attribute vec2 a_texcoord;\n"
"uniform vec4 src_subrect;\n");
fragment_header.append(
"precision mediump float;\n"
"uniform sampler2D s_texture;\n");
vertex_program.append(
" gl_Position = vec4(a_position, 0.0, 1.0);\n"
" vec2 texcoord = src_subrect.xy + a_texcoord * src_subrect.zw;\n");
switch (type) {
case SHADER_BILINEAR:
shared_variables.append("varying vec2 v_texcoord;\n");
vertex_program.append(" v_texcoord = texcoord;\n");
fragment_program.append(
" gl_FragColor = texture2D(s_texture, v_texcoord);\n");
break;
case SHADER_BILINEAR2:
// This is equivialent to two passes of the BILINEAR shader above.
// It can be used to scale an image down 1.0x-2.0x in either dimension,
// or exactly 4x.
shared_variables.append(
"varying vec4 v_texcoords;\n"); // 2 texcoords packed in one quad
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
" step /= 4.0;\n"
" v_texcoords.xy = texcoord + step;\n"
" v_texcoords.zw = texcoord - step;\n");
fragment_program.append(
" gl_FragColor = (texture2D(s_texture, v_texcoords.xy) +\n"
" texture2D(s_texture, v_texcoords.zw)) / 2.0;\n");
break;
case SHADER_BILINEAR3:
// This is kind of like doing 1.5 passes of the BILINEAR shader.
// It can be used to scale an image down 1.5x-3.0x, or exactly 6x.
shared_variables.append(
"varying vec4 v_texcoords1;\n" // 2 texcoords packed in one quad
"varying vec2 v_texcoords2;\n");
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
" step /= 3.0;\n"
" v_texcoords1.xy = texcoord + step;\n"
" v_texcoords1.zw = texcoord;\n"
" v_texcoords2 = texcoord - step;\n");
fragment_program.append(
" gl_FragColor = (texture2D(s_texture, v_texcoords1.xy) +\n"
" texture2D(s_texture, v_texcoords1.zw) +\n"
" texture2D(s_texture, v_texcoords2)) / 3.0;\n");
break;
case SHADER_BILINEAR4:
// This is equivialent to three passes of the BILINEAR shader above,
// It can be used to scale an image down 2.0x-4.0x or exactly 8x.
shared_variables.append("varying vec4 v_texcoords[2];\n");
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
" step /= 8.0;\n"
" v_texcoords[0].xy = texcoord - step * 3.0;\n"
" v_texcoords[0].zw = texcoord - step;\n"
" v_texcoords[1].xy = texcoord + step;\n"
" v_texcoords[1].zw = texcoord + step * 3.0;\n");
fragment_program.append(
" gl_FragColor = (\n"
" texture2D(s_texture, v_texcoords[0].xy) +\n"
" texture2D(s_texture, v_texcoords[0].zw) +\n"
" texture2D(s_texture, v_texcoords[1].xy) +\n"
" texture2D(s_texture, v_texcoords[1].zw)) / 4.0;\n");
break;
case SHADER_BILINEAR2X2:
// This is equivialent to four passes of the BILINEAR shader above.
// Two in each dimension. It can be used to scale an image down
// 1.0x-2.0x in both X and Y directions. Or, it could be used to
// scale an image down by exactly 4x in both dimensions.
shared_variables.append("varying vec4 v_texcoords[2];\n");
vertex_header.append("uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = src_subrect.zw / 4.0 / dst_pixelsize;\n"
" v_texcoords[0].xy = texcoord + vec2(step.x, step.y);\n"
" v_texcoords[0].zw = texcoord + vec2(step.x, -step.y);\n"
" v_texcoords[1].xy = texcoord + vec2(-step.x, step.y);\n"
" v_texcoords[1].zw = texcoord + vec2(-step.x, -step.y);\n");
fragment_program.append(
" gl_FragColor = (\n"
" texture2D(s_texture, v_texcoords[0].xy) +\n"
" texture2D(s_texture, v_texcoords[0].zw) +\n"
" texture2D(s_texture, v_texcoords[1].xy) +\n"
" texture2D(s_texture, v_texcoords[1].zw)) / 4.0;\n");
break;
case SHADER_BICUBIC_HALF_1D:
// This scales down texture by exactly half in one dimension.
// directions in one pass. We use bilinear lookup to reduce
// the number of texture reads from 8 to 4
shared_variables.append(
"const float CenterDist = 99.0 / 140.0;\n"
"const float LobeDist = 11.0 / 4.0;\n"
"const float CenterWeight = 35.0 / 64.0;\n"
"const float LobeWeight = -3.0 / 64.0;\n"
"varying vec4 v_texcoords[2];\n");
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 src_pixelsize;\n");
vertex_program.append(
" vec2 step = src_subrect.zw * scaling_vector / src_pixelsize;\n"
" v_texcoords[0].xy = texcoord - LobeDist * step;\n"
" v_texcoords[0].zw = texcoord - CenterDist * step;\n"
" v_texcoords[1].xy = texcoord + CenterDist * step;\n"
" v_texcoords[1].zw = texcoord + LobeDist * step;\n");
fragment_program.append(
" gl_FragColor = \n"
// Lobe pixels
" (texture2D(s_texture, v_texcoords[0].xy) +\n"
" texture2D(s_texture, v_texcoords[1].zw)) *\n"
" LobeWeight +\n"
// Center pixels
" (texture2D(s_texture, v_texcoords[0].zw) +\n"
" texture2D(s_texture, v_texcoords[1].xy)) *\n"
" CenterWeight;\n");
break;
case SHADER_BICUBIC_UPSCALE:
// When scaling up, we need 4 texture reads, but we can
// save some instructions because will know in which range of
// the bicubic function each call call to the bicubic function
// will be in.
// Also, when sampling the bicubic function like this, the sum
// is always exactly one, so we can skip normalization as well.
shared_variables.append("varying vec2 v_texcoord;\n");
vertex_program.append(" v_texcoord = texcoord;\n");
fragment_header.append(
"uniform vec2 src_pixelsize;\n"
"uniform vec2 scaling_vector;\n"
"const float a = -0.5;\n"
// This function is equivialent to calling the bicubic
// function with x-1, x, 1-x and 2-x
// (assuming 0 <= x < 1)
"vec4 filt4(float x) {\n"
" return vec4(x * x * x, x * x, x, 1) *\n"
" mat4( a, -2.0 * a, a, 0.0,\n"
" a + 2.0, -a - 3.0, 0.0, 1.0,\n"
" -a - 2.0, 3.0 + 2.0 * a, -a, 0.0,\n"
" -a, a, 0.0, 0.0);\n"
"}\n"
"mat4 pixels_x(vec2 pos, vec2 step) {\n"
" return mat4(\n"
" texture2D(s_texture, pos - step),\n"
" texture2D(s_texture, pos),\n"
" texture2D(s_texture, pos + step),\n"
" texture2D(s_texture, pos + step * 2.0));\n"
"}\n");
fragment_program.append(
" vec2 pixel_pos = v_texcoord * src_pixelsize - \n"
" scaling_vector / 2.0;\n"
" float frac = fract(dot(pixel_pos, scaling_vector));\n"
" vec2 base = (floor(pixel_pos) + vec2(0.5)) / src_pixelsize;\n"
" vec2 step = scaling_vector / src_pixelsize;\n"
" gl_FragColor = pixels_x(base, step) * filt4(frac);\n");
break;
case SHADER_PLANAR:
// Converts four RGBA pixels into one pixel. Each RGBA
// pixel will be dot-multiplied with the color weights and
// then placed into a component of the output. This is used to
// convert RGBA textures into Y, U and V textures. We do this
// because single-component textures are not renderable on all
// architectures.
shared_variables.append("varying vec4 v_texcoords[2];\n");
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
" step /= 4.0;\n"
" v_texcoords[0].xy = texcoord - step * 1.5;\n"
" v_texcoords[0].zw = texcoord - step * 0.5;\n"
" v_texcoords[1].xy = texcoord + step * 0.5;\n"
" v_texcoords[1].zw = texcoord + step * 1.5;\n");
fragment_header.append("uniform vec4 color_weights;\n");
fragment_program.append(
" gl_FragColor = color_weights * mat4(\n"
" vec4(texture2D(s_texture, v_texcoords[0].xy).rgb, 1.0),\n"
" vec4(texture2D(s_texture, v_texcoords[0].zw).rgb, 1.0),\n"
" vec4(texture2D(s_texture, v_texcoords[1].xy).rgb, 1.0),\n"
" vec4(texture2D(s_texture, v_texcoords[1].zw).rgb, 1.0));\n");
break;
case SHADER_YUV_MRT_PASS1:
// RGB24 to YV12 in two passes; writing two 8888 targets each pass.
//
// YV12 is full-resolution luma and half-resolution blue/red chroma.
//
// (original)
// RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
// RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
// RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
// RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
// RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
// RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
// |
// | (y plane) (temporary)
// | YYYY YYYY UUVV UUVV
// +--> { YYYY YYYY + UUVV UUVV }
// YYYY YYYY UUVV UUVV
// First YYYY YYYY UUVV UUVV
// pass YYYY YYYY UUVV UUVV
// YYYY YYYY UUVV UUVV
// |
// | (u plane) (v plane)
// Second | UUUU VVVV
// pass +--> { UUUU + VVVV }
// UUUU VVVV
//
shared_variables.append("varying vec4 v_texcoords[2];\n");
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
" step /= 4.0;\n"
" v_texcoords[0].xy = texcoord - step * 1.5;\n"
" v_texcoords[0].zw = texcoord - step * 0.5;\n"
" v_texcoords[1].xy = texcoord + step * 0.5;\n"
" v_texcoords[1].zw = texcoord + step * 1.5;\n");
fragment_directives.append("#extension GL_EXT_draw_buffers : enable\n");
fragment_header.append(
"const vec3 kRGBtoY = vec3(0.257, 0.504, 0.098);\n"
"const float kYBias = 0.0625;\n"
// Divide U and V by two to compensate for averaging below.
"const vec3 kRGBtoU = vec3(-0.148, -0.291, 0.439) / 2.0;\n"
"const vec3 kRGBtoV = vec3(0.439, -0.368, -0.071) / 2.0;\n"
"const float kUVBias = 0.5;\n");
fragment_program.append(
" vec3 pixel1 = texture2D(s_texture, v_texcoords[0].xy).rgb;\n"
" vec3 pixel2 = texture2D(s_texture, v_texcoords[0].zw).rgb;\n"
" vec3 pixel3 = texture2D(s_texture, v_texcoords[1].xy).rgb;\n"
" vec3 pixel4 = texture2D(s_texture, v_texcoords[1].zw).rgb;\n"
" vec3 pixel12 = pixel1 + pixel2;\n"
" vec3 pixel34 = pixel3 + pixel4;\n"
" gl_FragData[0] = vec4(dot(pixel1, kRGBtoY),\n"
" dot(pixel2, kRGBtoY),\n"
" dot(pixel3, kRGBtoY),\n"
" dot(pixel4, kRGBtoY)) + kYBias;\n"
" gl_FragData[1] = vec4(dot(pixel12, kRGBtoU),\n"
" dot(pixel34, kRGBtoU),\n"
" dot(pixel12, kRGBtoV),\n"
" dot(pixel34, kRGBtoV)) + kUVBias;\n");
break;
case SHADER_YUV_MRT_PASS2:
// We're just sampling two pixels and unswizzling them. There's
// no need to do vertical scaling with math, since bilinear
// interpolation in the sampler takes care of that.
shared_variables.append("varying vec4 v_texcoords;\n");
vertex_header.append(
"uniform vec2 scaling_vector;\n"
"uniform vec2 dst_pixelsize;\n");
vertex_program.append(
" vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
" step /= 2.0;\n"
" v_texcoords.xy = texcoord - step * 0.5;\n"
" v_texcoords.zw = texcoord + step * 0.5;\n");
fragment_directives.append("#extension GL_EXT_draw_buffers : enable\n");
fragment_program.append(
" vec4 lo_uuvv = texture2D(s_texture, v_texcoords.xy);\n"
" vec4 hi_uuvv = texture2D(s_texture, v_texcoords.zw);\n"
" gl_FragData[0] = vec4(lo_uuvv.rg, hi_uuvv.rg);\n"
" gl_FragData[1] = vec4(lo_uuvv.ba, hi_uuvv.ba);\n");
break;
}
if (swizzle) {
switch(type) {
case SHADER_YUV_MRT_PASS1:
fragment_program.append(" gl_FragData[0] = gl_FragData[0].bgra;\n");
break;
case SHADER_YUV_MRT_PASS2:
fragment_program.append(" gl_FragData[0] = gl_FragData[0].bgra;\n");
fragment_program.append(" gl_FragData[1] = gl_FragData[1].bgra;\n");
break;
default:
fragment_program.append(" gl_FragColor = gl_FragColor.bgra;\n");
break;
}
}
vertex_program = vertex_header + shared_variables + "void main() {\n" +
vertex_program + "}\n";
fragment_program = fragment_directives + fragment_header +
shared_variables + "void main() {\n" + fragment_program +
"}\n";
cache_entry->Setup(vertex_program.c_str(), fragment_program.c_str());
}
return cache_entry;
}
void ShaderProgram::Setup(const GLchar* vertex_shader_text,
const GLchar* fragment_shader_text) {
// Shaders to map the source texture to |dst_texture_|.
GLuint vertex_shader =
helper_->CompileShaderFromSource(vertex_shader_text, GL_VERTEX_SHADER);
if (vertex_shader == 0)
return;
gl_->AttachShader(program_, vertex_shader);
gl_->DeleteShader(vertex_shader);
GLuint fragment_shader = helper_->CompileShaderFromSource(
fragment_shader_text, GL_FRAGMENT_SHADER);
if (fragment_shader == 0)
return;
gl_->AttachShader(program_, fragment_shader);
gl_->DeleteShader(fragment_shader);
gl_->LinkProgram(program_);
GLint link_status = 0;
gl_->GetProgramiv(program_, GL_LINK_STATUS, &link_status);
if (!link_status)
return;
position_location_ = gl_->GetAttribLocation(program_, "a_position");
texcoord_location_ = gl_->GetAttribLocation(program_, "a_texcoord");
texture_location_ = gl_->GetUniformLocation(program_, "s_texture");
src_subrect_location_ = gl_->GetUniformLocation(program_, "src_subrect");
src_pixelsize_location_ = gl_->GetUniformLocation(program_, "src_pixelsize");
dst_pixelsize_location_ = gl_->GetUniformLocation(program_, "dst_pixelsize");
scaling_vector_location_ =
gl_->GetUniformLocation(program_, "scaling_vector");
color_weights_location_ = gl_->GetUniformLocation(program_, "color_weights");
return;
}
void ShaderProgram::UseProgram(const gfx::Size& src_size,
const gfx::Rect& src_subrect,
const gfx::Size& dst_size,
bool scale_x,
bool flip_y,
GLfloat color_weights[4]) {
gl_->UseProgram(program_);
// OpenGL defines the last parameter to VertexAttribPointer as type
// "const GLvoid*" even though it is actually an offset into the buffer
// object's data store and not a pointer to the client's address space.
const void* offsets[2] = {
0, reinterpret_cast<const void*>(2 * sizeof(GLfloat))
};
gl_->VertexAttribPointer(position_location_,
2,
GL_FLOAT,
GL_FALSE,
4 * sizeof(GLfloat),
offsets[0]);
gl_->EnableVertexAttribArray(position_location_);
gl_->VertexAttribPointer(texcoord_location_,
2,
GL_FLOAT,
GL_FALSE,
4 * sizeof(GLfloat),
offsets[1]);
gl_->EnableVertexAttribArray(texcoord_location_);
gl_->Uniform1i(texture_location_, 0);
// Convert |src_subrect| to texture coordinates.
GLfloat src_subrect_texcoord[] = {
static_cast<float>(src_subrect.x()) / src_size.width(),
static_cast<float>(src_subrect.y()) / src_size.height(),
static_cast<float>(src_subrect.width()) / src_size.width(),
static_cast<float>(src_subrect.height()) / src_size.height(), };
if (flip_y) {
src_subrect_texcoord[1] += src_subrect_texcoord[3];
src_subrect_texcoord[3] *= -1.0;
}
gl_->Uniform4fv(src_subrect_location_, 1, src_subrect_texcoord);
gl_->Uniform2f(src_pixelsize_location_, src_size.width(), src_size.height());
gl_->Uniform2f(dst_pixelsize_location_,
static_cast<float>(dst_size.width()),
static_cast<float>(dst_size.height()));
gl_->Uniform2f(
scaling_vector_location_, scale_x ? 1.0 : 0.0, scale_x ? 0.0 : 1.0);
gl_->Uniform4fv(color_weights_location_, 1, color_weights);
}
} // namespace content