gfxapi/gles/read_framebuffer.go - platform/tools/gpu - Git at Google

 // Copyright (C) 2015 The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package gles

 import (
 	"fmt"
 	"math/rand"

 	"android.googlesource.com/platform/tools/gpu/atom"
 	"android.googlesource.com/platform/tools/gpu/binary"
 	"android.googlesource.com/platform/tools/gpu/database"
 	"android.googlesource.com/platform/tools/gpu/gfxapi"
 	"android.googlesource.com/platform/tools/gpu/log"
 	"android.googlesource.com/platform/tools/gpu/memory"
 	"android.googlesource.com/platform/tools/gpu/replay"
 	"android.googlesource.com/platform/tools/gpu/replay/builder"
 	"android.googlesource.com/platform/tools/gpu/replay/value"
 )

 func readFramebufferDepth(out chan replay.Image) atom.Atom {
 	return replay.Custom(func(i atom.ID, s *gfxapi.State, d database.Database, l log.Logger, b *builder.Builder) error {
 		arch := s.Architecture
 		c := getContext(s)

 		colorW, colorH, err := getState(s).getFramebufferAttachmentSize(gfxapi.FramebufferAttachmentColor)
 		if err != nil {
 			return err
 		}
 		depthW, depthH, err := getState(s).getFramebufferAttachmentSize(gfxapi.FramebufferAttachmentDepth)
 		if err != nil {
 			return err
 		}

 		const (
 			uTextureLocation      UniformLocation   = 0
 			aScreenCoordsLocation AttributeLocation = 0

 			vertexShaderSource string = `
 				precision highp float;
 				attribute vec2 aScreenCoords;
 				varying vec2 vTexCoords;

 				void main() {
 					vTexCoords = aScreenCoords / 2. + vec2(0.5, 0.5);
 					gl_Position = vec4(aScreenCoords.xy, 0., 1.);
 				}`
 			fragmentShaderSource string = `
 				precision highp float;
 				uniform sampler2D uTexture;
 				varying vec2 vTexCoords;

 				vec4 float2rgba(float f) {
 					vec4 v = fract(f * vec4(1., 255., 65025., 16581375.));
 					return v - vec4(v.yzw, 0.) / 255.;
 				}

 				void main() {
 					float sample = texture2D(uTexture, vTexCoords).r;
 					gl_FragColor = float2rgba(sample);
 				}`
 		)

 		var (
 			origProgramID            = c.BoundProgram
 			origRenderbufferID       = c.BoundRenderbuffers[GLenum_GL_RENDERBUFFER]
 			origReadFramebufferID    = c.BoundFramebuffers[GLenum_GL_READ_FRAMEBUFFER]
 			origDrawFramebufferID    = c.BoundFramebuffers[GLenum_GL_DRAW_FRAMEBUFFER]
 			origTextureID            = c.TextureUnits[c.ActiveTextureUnit][GLenum_GL_TEXTURE_2D]
 			origArrayBufferID        = c.BoundBuffers[GLenum_GL_ARRAY_BUFFER]
 			origElementArrayBufferID = c.BoundBuffers[GLenum_GL_ELEMENT_ARRAY_BUFFER]
 			origActiveTextureUnit    = int32(c.ActiveTextureUnit - GLenum_GL_TEXTURE0)

 			inW  = int32(depthW)
 			inH  = int32(depthH)
 			outW = int32(colorW)
 			outH = int32(colorH)
 		)

 		// Generate new unused object IDs.
 		renderbufferID := RenderbufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Renderbuffers[RenderbufferId(x)]; return ok }))
 		framebufferID := FramebufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Framebuffers[FramebufferId(x)]; return ok }))
 		textureID := TextureId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Textures[TextureId(x)]; return ok }))
 		programID := ProgramId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Programs[ProgramId(x)]; return ok }))
 		vertexShaderID := ShaderId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Shaders[ShaderId(x)]; return ok }))
 		fragmentShaderID := ShaderId(newUnusedID(func(x uint32) bool {
 			_, ok := c.Instances.Shaders[ShaderId(x)]
 			return ok || ShaderId(x) == vertexShaderID
 		}))

 		// 2D vertices positions for a full screen 2D triangle strip.
 		positions := []float32{-1., -1., 1., -1., -1., 1., 1., 1.}

 		// Temporarily change rasterizing/blending state and enable VAP 0.
 		undoList := []atom.Atom{}
 		for _, cap := range []GLenum{
 			GLenum_GL_BLEND,
 			GLenum_GL_CULL_FACE,
 			GLenum_GL_DEPTH_TEST,
 			GLenum_GL_SCISSOR_TEST,
 			GLenum_GL_STENCIL_TEST,
 		} {
 			capability := cap
 			if c.Capabilities[capability] {
 				NewGlDisable(capability).Replay(i, s, d, l, b)
 				undoList = append(undoList, NewGlEnable(capability))
 			}
 		}
 		if !c.VertexAttributeArrays[aScreenCoordsLocation].Enabled {
 			NewGlEnableVertexAttribArray(aScreenCoordsLocation).Replay(i, s, d, l, b)
 			undoList = append(undoList, NewGlDisableVertexAttribArray(aScreenCoordsLocation))
 		}

 		replayEach(i, s, d, l, b,
 			// Setup new framebuffer/renderbuffer.
 			NewGlGenFramebuffers(1, memory.Tmp).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),
 			NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, framebufferID),
 			NewGlGenRenderbuffers(1, memory.Tmp).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
 			NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, renderbufferID),
 			NewGlRenderbufferStorage(GLenum_GL_RENDERBUFFER, GLenum_GL_RGBA8, GLsizei(outW), GLsizei(outH)),
 			NewGlFramebufferRenderbuffer(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_COLOR_ATTACHMENT0, GLenum_GL_RENDERBUFFER, renderbufferID),

 			// Setup depth texture.
 			NewGlGenTextures(1, memory.Tmp).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, textureID)),
 			NewGlBindTexture(GLenum_GL_TEXTURE_2D, textureID),
 			NewGlTexImage2D(GLenum_GL_TEXTURE_2D, 0, GLint(GLenum_GL_DEPTH24_STENCIL8), GLsizei(outW), GLsizei(outH), 0, GLenum_GL_DEPTH_STENCIL, GLenum_GL_UNSIGNED_INT_24_8, memory.Nullptr),
 			NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_MIN_FILTER, GLint(GLenum_GL_NEAREST)),
 			NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_MAG_FILTER, GLint(GLenum_GL_NEAREST)),
 			NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_WRAP_S, GLint(GLenum_GL_CLAMP_TO_EDGE)),
 			NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_WRAP_T, GLint(GLenum_GL_CLAMP_TO_EDGE)),

 			// Blit depth attachment.
 			NewGlFramebufferTexture2D(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_DEPTH_ATTACHMENT, GLenum_GL_TEXTURE_2D, textureID, 0),
 			NewGlBlitFramebuffer(0, 0, GLint(inW), GLint(inH), 0, 0, GLint(outW), GLint(outH), GLbitfield_GL_DEPTH_BUFFER_BIT, GLenum_GL_NEAREST),
 			NewGlFramebufferTexture2D(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_DEPTH_ATTACHMENT, GLenum_GL_TEXTURE_2D, TextureId(0), 0),

 			// Bind new framebuffer.
 			NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, framebufferID),

 			// Render depth texture to framebuffer color attachment.
 			NewGlClear(GLbitfield_GL_COLOR_BUFFER_BIT),
 		)

 		// Create the shader program
 		replayEach(i, s, d, l, b,
 			NewProgram(arch, d, l, vertexShaderID, fragmentShaderID, programID, vertexShaderSource, fragmentShaderSource)...)

 		replayEach(i, s, d, l, b,
 			NewGlBindAttribLocation(programID, aScreenCoordsLocation, "aScreenCoords"),
 			NewGlLinkProgram(programID),
 			NewGlUseProgram(programID),
 			NewGlBindTexture(GLenum_GL_TEXTURE_2D, textureID),
 			NewGlGetUniformLocation(programID, "uTexture", uTextureLocation),
 			NewGlUniform1i(uTextureLocation, GLint(origActiveTextureUnit)),
 			NewGlBindBuffer(GLenum_GL_ARRAY_BUFFER, 0),
 			NewGlBindBuffer(GLenum_GL_ELEMENT_ARRAY_BUFFER, 0),
 			NewGlVertexAttribPointer(aScreenCoordsLocation, 2, GLenum_GL_FLOAT, false, 0, memory.Tmp),
 			NewGlDrawArrays(GLenum_GL_TRIANGLE_STRIP, 0, 4).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, positions)),
 		)

 		postColorData(i, s, d, l, b, outW, outH, out)

 		// Restore conditionally changed state.
 		replayEach(i, s, d, l, b, undoList...)

 		replayEach(i, s, d, l, b,
 			// Restore buffer/vertexAttrib state.
 			NewGlBindBuffer(GLenum_GL_ELEMENT_ARRAY_BUFFER, origElementArrayBufferID),
 			NewGlBindBuffer(GLenum_GL_ARRAY_BUFFER, origArrayBufferID),
 			// Note: we're not restoring the original VertexAttribPointer as we may re-enter an inconsistent state, which would abort the current replay batch.
 			// NewGlVertexAttribPointer(aScreenCoordsLocation, origVertexAttrib.Size, origVertexAttrib.Type, origVertexAttrib.Normalized, origVertexAttrib.Stride, VertexPointer(origVertexAttrib.Data)),

 			// Restore texture state.
 			NewGlBindTexture(GLenum_GL_TEXTURE_2D, origTextureID),
 			NewGlDeleteTextures(1, memory.Tmp).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, textureID)),

 			// Restore framebuffer/renderbuffer state.
 			NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, origRenderbufferID),
 			NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, origReadFramebufferID),
 			NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, origDrawFramebufferID),
 			NewGlDeleteRenderbuffers(1, memory.Tmp).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
 			NewGlDeleteFramebuffers(1, memory.Tmp).
 				AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),

 			// Restore program state.
 			NewGlUseProgram(origProgramID),
 			NewGlDeleteProgram(programID),
 			NewGlDeleteShader(vertexShaderID),
 			NewGlDeleteShader(fragmentShaderID),
 		)

 		return nil
 	})
 }

 func readFramebufferColor(width, height uint32, out chan replay.Image) atom.Atom {
 	return replay.Custom(func(i atom.ID, s *gfxapi.State, d database.Database, l log.Logger, b *builder.Builder) error {
 		arch := s.Architecture
 		c := getContext(s)

 		colorW, colorH, err := getState(s).getFramebufferAttachmentSize(gfxapi.FramebufferAttachmentColor)
 		if err != nil {
 			return err
 		}

 		var (
 			origRenderbufferID    = c.BoundRenderbuffers[GLenum_GL_RENDERBUFFER]
 			origReadFramebufferID = c.BoundFramebuffers[GLenum_GL_READ_FRAMEBUFFER]
 			origDrawFramebufferID = c.BoundFramebuffers[GLenum_GL_DRAW_FRAMEBUFFER]

 			inW  = int32(colorW)
 			inH  = int32(colorH)
 			outW = int32(width)
 			outH = int32(height)
 		)

 		// Generate new unused object IDs.
 		renderbufferID := RenderbufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Renderbuffers[RenderbufferId(x)]; return ok }))
 		framebufferID := FramebufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Framebuffers[FramebufferId(x)]; return ok }))

 		if inW == outW && inH == outH {
 			postColorData(i, s, d, l, b, outW, outH, out)
 		} else {
 			ctx := getContext(s)
 			origScissor := ctx.Rasterizing.Scissor

 			replayEach(i, s, d, l, b,
 				NewGlScissor(0, 0, GLsizei(colorW), GLsizei(colorH)),
 				NewGlGenFramebuffers(1, memory.Tmp).
 					AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),
 				NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, framebufferID),
 				NewGlGenRenderbuffers(1, memory.Tmp).
 					AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
 				NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, renderbufferID),
 				NewGlRenderbufferStorage(GLenum_GL_RENDERBUFFER, GLenum_GL_RGBA8, GLsizei(outW), GLsizei(outH)),
 				NewGlFramebufferRenderbuffer(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_COLOR_ATTACHMENT0, GLenum_GL_RENDERBUFFER, renderbufferID),
 				NewGlBlitFramebuffer(0, 0, GLint(inW), GLint(inH), 0, 0, GLint(outW), GLint(outH), GLbitfield_GL_COLOR_BUFFER_BIT, GLenum_GL_LINEAR),
 				NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, framebufferID),
 			)

 			postColorData(i, s, d, l, b, outW, outH, out)

 			replayEach(i, s, d, l, b,
 				NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, origRenderbufferID),
 				NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, origReadFramebufferID),
 				NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, origDrawFramebufferID),
 				NewGlDeleteRenderbuffers(1, memory.Tmp).
 					AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
 				NewGlDeleteFramebuffers(1, memory.Tmp).
 					AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),
 				NewGlScissor(origScissor.X, origScissor.Y, origScissor.Width, origScissor.Height),
 			)
 		}

 		return nil
 	})
 }

 func postColorData(i atom.ID, s *gfxapi.State, d database.Database, l log.Logger, b *builder.Builder, width, height int32, img chan<- replay.Image) {
 	ctx := getContext(s)
 	origPackAlignment := ctx.PixelStorage[GLenum_GL_PACK_ALIGNMENT]
 	if origPackAlignment != 1 {
 		NewGlPixelStorei(GLenum_GL_PACK_ALIGNMENT, 1).Replay(i, s, d, l, b)
 		defer NewGlPixelStorei(GLenum_GL_PACK_ALIGNMENT, origPackAlignment).Replay(i, s, d, l, b)
 	}
 	if origPackBuffer, ok := ctx.BoundBuffers[GLenum_GL_PIXEL_PACK_BUFFER]; ok && origPackBuffer != 0 {
 		NewGlBindBuffer(GLenum_GL_PIXEL_PACK_BUFFER, 0).Replay(i, s, d, l, b)
 		defer NewGlBindBuffer(GLenum_GL_PIXEL_PACK_BUFFER, origPackBuffer).Replay(i, s, d, l, b)
 	}

 	imageSize := uint64(width * height * 4)
 	NewGlReadPixels(0, 0, GLsizei(width), GLsizei(height), GLenum_GL_RGBA, GLenum_GL_UNSIGNED_BYTE, memory.Tmp).Replay(i, s, d, l, b)
 	b.Post(value.RemappedPointer(memory.Tmp.Address), imageSize, func(d binary.Decoder, err error) error {
 		var data []byte
 		if err == nil {
 			data = make([]byte, imageSize)
 			err = d.Data(data)
 		}
 		if err != nil {
 			err = fmt.Errorf("Could not read framebuffer data (expected length %d bytes): %v", imageSize, err)
 			data = nil
 		}
 		img <- replay.Image{Data: data, Error: err}
 		return err
 	})
 }

 func replayEach(i atom.ID, s *gfxapi.State, d database.Database, l log.Logger, b *builder.Builder, atoms ...atom.Atom) {
 	for _, a := range atoms {
 		if r, ok := a.(replay.Replayer); ok {
 			r.Replay(i, s, d, l, b)
 		}
 	}
 }

 func newUnusedID(existenceTest func(uint32) bool) uint32 {
 	for {
 		x := rand.Uint32()
 		if !existenceTest(x) {
 			return x
 		}
 	}
 }
	// Copyright (C) 2015 The Android Open Source Project
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package gles

	import (
	"fmt"
	"math/rand"

	"android.googlesource.com/platform/tools/gpu/atom"
	"android.googlesource.com/platform/tools/gpu/binary"
	"android.googlesource.com/platform/tools/gpu/database"
	"android.googlesource.com/platform/tools/gpu/gfxapi"
	"android.googlesource.com/platform/tools/gpu/log"
	"android.googlesource.com/platform/tools/gpu/memory"
	"android.googlesource.com/platform/tools/gpu/replay"
	"android.googlesource.com/platform/tools/gpu/replay/builder"
	"android.googlesource.com/platform/tools/gpu/replay/value"
	)

	func readFramebufferDepth(out chan replay.Image) atom.Atom {
	return replay.Custom(func(i atom.ID, s gfxapi.State, d database.Database, l log.Logger, b builder.Builder) error {
	arch := s.Architecture
	c := getContext(s)

	colorW, colorH, err := getState(s).getFramebufferAttachmentSize(gfxapi.FramebufferAttachmentColor)
	if err != nil {
	return err
	}
	depthW, depthH, err := getState(s).getFramebufferAttachmentSize(gfxapi.FramebufferAttachmentDepth)
	if err != nil {
	return err
	}

	const (
	uTextureLocation UniformLocation = 0
	aScreenCoordsLocation AttributeLocation = 0

	vertexShaderSource string = `
	precision highp float;
	attribute vec2 aScreenCoords;
	varying vec2 vTexCoords;

	void main() {
	vTexCoords = aScreenCoords / 2. + vec2(0.5, 0.5);
	gl_Position = vec4(aScreenCoords.xy, 0., 1.);
	}`
	fragmentShaderSource string = `
	precision highp float;
	uniform sampler2D uTexture;
	varying vec2 vTexCoords;

	vec4 float2rgba(float f) {
	vec4 v = fract(f * vec4(1., 255., 65025., 16581375.));
	return v - vec4(v.yzw, 0.) / 255.;
	}

	void main() {
	float sample = texture2D(uTexture, vTexCoords).r;
	gl_FragColor = float2rgba(sample);
	}`
	)

	var (
	origProgramID = c.BoundProgram
	origRenderbufferID = c.BoundRenderbuffers[GLenum_GL_RENDERBUFFER]
	origReadFramebufferID = c.BoundFramebuffers[GLenum_GL_READ_FRAMEBUFFER]
	origDrawFramebufferID = c.BoundFramebuffers[GLenum_GL_DRAW_FRAMEBUFFER]
	origTextureID = c.TextureUnits[c.ActiveTextureUnit][GLenum_GL_TEXTURE_2D]
	origArrayBufferID = c.BoundBuffers[GLenum_GL_ARRAY_BUFFER]
	origElementArrayBufferID = c.BoundBuffers[GLenum_GL_ELEMENT_ARRAY_BUFFER]
	origActiveTextureUnit = int32(c.ActiveTextureUnit - GLenum_GL_TEXTURE0)

	inW = int32(depthW)
	inH = int32(depthH)
	outW = int32(colorW)
	outH = int32(colorH)
	)

	// Generate new unused object IDs.
	renderbufferID := RenderbufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Renderbuffers[RenderbufferId(x)]; return ok }))
	framebufferID := FramebufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Framebuffers[FramebufferId(x)]; return ok }))
	textureID := TextureId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Textures[TextureId(x)]; return ok }))
	programID := ProgramId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Programs[ProgramId(x)]; return ok }))
	vertexShaderID := ShaderId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Shaders[ShaderId(x)]; return ok }))
	fragmentShaderID := ShaderId(newUnusedID(func(x uint32) bool {
	_, ok := c.Instances.Shaders[ShaderId(x)]
	return ok \|\| ShaderId(x) == vertexShaderID
	}))

	// 2D vertices positions for a full screen 2D triangle strip.
	positions := []float32{-1., -1., 1., -1., -1., 1., 1., 1.}

	// Temporarily change rasterizing/blending state and enable VAP 0.
	undoList := []atom.Atom{}
	for _, cap := range []GLenum{
	GLenum_GL_BLEND,
	GLenum_GL_CULL_FACE,
	GLenum_GL_DEPTH_TEST,
	GLenum_GL_SCISSOR_TEST,
	GLenum_GL_STENCIL_TEST,
	} {
	capability := cap
	if c.Capabilities[capability] {
	NewGlDisable(capability).Replay(i, s, d, l, b)
	undoList = append(undoList, NewGlEnable(capability))
	}
	}
	if !c.VertexAttributeArrays[aScreenCoordsLocation].Enabled {
	NewGlEnableVertexAttribArray(aScreenCoordsLocation).Replay(i, s, d, l, b)
	undoList = append(undoList, NewGlDisableVertexAttribArray(aScreenCoordsLocation))
	}

	replayEach(i, s, d, l, b,
	// Setup new framebuffer/renderbuffer.
	NewGlGenFramebuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),
	NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, framebufferID),
	NewGlGenRenderbuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
	NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, renderbufferID),
	NewGlRenderbufferStorage(GLenum_GL_RENDERBUFFER, GLenum_GL_RGBA8, GLsizei(outW), GLsizei(outH)),
	NewGlFramebufferRenderbuffer(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_COLOR_ATTACHMENT0, GLenum_GL_RENDERBUFFER, renderbufferID),

	// Setup depth texture.
	NewGlGenTextures(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, textureID)),
	NewGlBindTexture(GLenum_GL_TEXTURE_2D, textureID),
	NewGlTexImage2D(GLenum_GL_TEXTURE_2D, 0, GLint(GLenum_GL_DEPTH24_STENCIL8), GLsizei(outW), GLsizei(outH), 0, GLenum_GL_DEPTH_STENCIL, GLenum_GL_UNSIGNED_INT_24_8, memory.Nullptr),
	NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_MIN_FILTER, GLint(GLenum_GL_NEAREST)),
	NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_MAG_FILTER, GLint(GLenum_GL_NEAREST)),
	NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_WRAP_S, GLint(GLenum_GL_CLAMP_TO_EDGE)),
	NewGlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_WRAP_T, GLint(GLenum_GL_CLAMP_TO_EDGE)),

	// Blit depth attachment.
	NewGlFramebufferTexture2D(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_DEPTH_ATTACHMENT, GLenum_GL_TEXTURE_2D, textureID, 0),
	NewGlBlitFramebuffer(0, 0, GLint(inW), GLint(inH), 0, 0, GLint(outW), GLint(outH), GLbitfield_GL_DEPTH_BUFFER_BIT, GLenum_GL_NEAREST),
	NewGlFramebufferTexture2D(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_DEPTH_ATTACHMENT, GLenum_GL_TEXTURE_2D, TextureId(0), 0),

	// Bind new framebuffer.
	NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, framebufferID),

	// Render depth texture to framebuffer color attachment.
	NewGlClear(GLbitfield_GL_COLOR_BUFFER_BIT),
	)

	// Create the shader program
	replayEach(i, s, d, l, b,
	NewProgram(arch, d, l, vertexShaderID, fragmentShaderID, programID, vertexShaderSource, fragmentShaderSource)...)

	replayEach(i, s, d, l, b,
	NewGlBindAttribLocation(programID, aScreenCoordsLocation, "aScreenCoords"),
	NewGlLinkProgram(programID),
	NewGlUseProgram(programID),
	NewGlBindTexture(GLenum_GL_TEXTURE_2D, textureID),
	NewGlGetUniformLocation(programID, "uTexture", uTextureLocation),
	NewGlUniform1i(uTextureLocation, GLint(origActiveTextureUnit)),
	NewGlBindBuffer(GLenum_GL_ARRAY_BUFFER, 0),
	NewGlBindBuffer(GLenum_GL_ELEMENT_ARRAY_BUFFER, 0),
	NewGlVertexAttribPointer(aScreenCoordsLocation, 2, GLenum_GL_FLOAT, false, 0, memory.Tmp),
	NewGlDrawArrays(GLenum_GL_TRIANGLE_STRIP, 0, 4).
	AddRead(atom.Data(arch, d, l, memory.Tmp, positions)),
	)

	postColorData(i, s, d, l, b, outW, outH, out)

	// Restore conditionally changed state.
	replayEach(i, s, d, l, b, undoList...)

	replayEach(i, s, d, l, b,
	// Restore buffer/vertexAttrib state.
	NewGlBindBuffer(GLenum_GL_ELEMENT_ARRAY_BUFFER, origElementArrayBufferID),
	NewGlBindBuffer(GLenum_GL_ARRAY_BUFFER, origArrayBufferID),
	// Note: we're not restoring the original VertexAttribPointer as we may re-enter an inconsistent state, which would abort the current replay batch.
	// NewGlVertexAttribPointer(aScreenCoordsLocation, origVertexAttrib.Size, origVertexAttrib.Type, origVertexAttrib.Normalized, origVertexAttrib.Stride, VertexPointer(origVertexAttrib.Data)),

	// Restore texture state.
	NewGlBindTexture(GLenum_GL_TEXTURE_2D, origTextureID),
	NewGlDeleteTextures(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, textureID)),

	// Restore framebuffer/renderbuffer state.
	NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, origRenderbufferID),
	NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, origReadFramebufferID),
	NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, origDrawFramebufferID),
	NewGlDeleteRenderbuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
	NewGlDeleteFramebuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),

	// Restore program state.
	NewGlUseProgram(origProgramID),
	NewGlDeleteProgram(programID),
	NewGlDeleteShader(vertexShaderID),
	NewGlDeleteShader(fragmentShaderID),
	)

	return nil
	})
	}

	func readFramebufferColor(width, height uint32, out chan replay.Image) atom.Atom {
	return replay.Custom(func(i atom.ID, s gfxapi.State, d database.Database, l log.Logger, b builder.Builder) error {
	arch := s.Architecture
	c := getContext(s)

	colorW, colorH, err := getState(s).getFramebufferAttachmentSize(gfxapi.FramebufferAttachmentColor)
	if err != nil {
	return err
	}

	var (
	origRenderbufferID = c.BoundRenderbuffers[GLenum_GL_RENDERBUFFER]
	origReadFramebufferID = c.BoundFramebuffers[GLenum_GL_READ_FRAMEBUFFER]
	origDrawFramebufferID = c.BoundFramebuffers[GLenum_GL_DRAW_FRAMEBUFFER]

	inW = int32(colorW)
	inH = int32(colorH)
	outW = int32(width)
	outH = int32(height)
	)

	// Generate new unused object IDs.
	renderbufferID := RenderbufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Renderbuffers[RenderbufferId(x)]; return ok }))
	framebufferID := FramebufferId(newUnusedID(func(x uint32) bool { _, ok := c.Instances.Framebuffers[FramebufferId(x)]; return ok }))

	if inW == outW && inH == outH {
	postColorData(i, s, d, l, b, outW, outH, out)
	} else {
	ctx := getContext(s)
	origScissor := ctx.Rasterizing.Scissor

	replayEach(i, s, d, l, b,
	NewGlScissor(0, 0, GLsizei(colorW), GLsizei(colorH)),
	NewGlGenFramebuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),
	NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, framebufferID),
	NewGlGenRenderbuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
	NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, renderbufferID),
	NewGlRenderbufferStorage(GLenum_GL_RENDERBUFFER, GLenum_GL_RGBA8, GLsizei(outW), GLsizei(outH)),
	NewGlFramebufferRenderbuffer(GLenum_GL_DRAW_FRAMEBUFFER, GLenum_GL_COLOR_ATTACHMENT0, GLenum_GL_RENDERBUFFER, renderbufferID),
	NewGlBlitFramebuffer(0, 0, GLint(inW), GLint(inH), 0, 0, GLint(outW), GLint(outH), GLbitfield_GL_COLOR_BUFFER_BIT, GLenum_GL_LINEAR),
	NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, framebufferID),
	)

	postColorData(i, s, d, l, b, outW, outH, out)

	replayEach(i, s, d, l, b,
	NewGlBindRenderbuffer(GLenum_GL_RENDERBUFFER, origRenderbufferID),
	NewGlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, origReadFramebufferID),
	NewGlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, origDrawFramebufferID),
	NewGlDeleteRenderbuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, renderbufferID)),
	NewGlDeleteFramebuffers(1, memory.Tmp).
	AddRead(atom.Data(arch, d, l, memory.Tmp, framebufferID)),
	NewGlScissor(origScissor.X, origScissor.Y, origScissor.Width, origScissor.Height),
	)
	}

	return nil
	})
	}

	func postColorData(i atom.ID, s gfxapi.State, d database.Database, l log.Logger, b builder.Builder, width, height int32, img chan<- replay.Image) {
	ctx := getContext(s)
	origPackAlignment := ctx.PixelStorage[GLenum_GL_PACK_ALIGNMENT]
	if origPackAlignment != 1 {
	NewGlPixelStorei(GLenum_GL_PACK_ALIGNMENT, 1).Replay(i, s, d, l, b)
	defer NewGlPixelStorei(GLenum_GL_PACK_ALIGNMENT, origPackAlignment).Replay(i, s, d, l, b)
	}
	if origPackBuffer, ok := ctx.BoundBuffers[GLenum_GL_PIXEL_PACK_BUFFER]; ok && origPackBuffer != 0 {
	NewGlBindBuffer(GLenum_GL_PIXEL_PACK_BUFFER, 0).Replay(i, s, d, l, b)
	defer NewGlBindBuffer(GLenum_GL_PIXEL_PACK_BUFFER, origPackBuffer).Replay(i, s, d, l, b)
	}

	imageSize := uint64(width * height * 4)
	NewGlReadPixels(0, 0, GLsizei(width), GLsizei(height), GLenum_GL_RGBA, GLenum_GL_UNSIGNED_BYTE, memory.Tmp).Replay(i, s, d, l, b)
	b.Post(value.RemappedPointer(memory.Tmp.Address), imageSize, func(d binary.Decoder, err error) error {
	var data []byte
	if err == nil {
	data = make([]byte, imageSize)
	err = d.Data(data)
	}
	if err != nil {
	err = fmt.Errorf("Could not read framebuffer data (expected length %d bytes): %v", imageSize, err)
	data = nil
	}
	img <- replay.Image{Data: data, Error: err}
	return err
	})
	}

	func replayEach(i atom.ID, s gfxapi.State, d database.Database, l log.Logger, b builder.Builder, atoms ...atom.Atom) {
	for _, a := range atoms {
	if r, ok := a.(replay.Replayer); ok {
	r.Replay(i, s, d, l, b)
	}
	}
	}

	func newUnusedID(existenceTest func(uint32) bool) uint32 {
	for {
	x := rand.Uint32()
	if !existenceTest(x) {
	return x
	}
	}
	}