graphicsdriver/opengl: Experimental PBO implementation

This change is an experimental implementation to use Pixel Buffer
Objects. This reduces calls of glTexSubImage2D.

This works only on desktops. Unfortunately WebGL does not have
this features. Mobiles can have PBO as of OpenGL ES 3.

Updates #976

internal/graphicsdriver/opengl/context_desktop.go

@@ -22,6 +22,7 @@ package opengl
 import (
 	"errors"
 	"fmt"
+	"unsafe"
 
 	"github.com/hajimehoshi/ebiten/internal/driver"
 	"github.com/hajimehoshi/ebiten/internal/graphicsdriver/opengl/gl"
@@ -509,3 +510,42 @@ func (c *context) flush() {
 func (c *context) needsRestoring() bool {
 	return false
 }
+
+func (c *context) newPixelBufferObject(width, height int) buffer {
+	var bf buffer
+	_ = c.t.Call(func() error {
+		var b uint32
+		gl.GenBuffers(1, &b)
+		gl.BindBuffer(gl.PIXEL_UNPACK_BUFFER, b)
+		gl.BufferData(gl.PIXEL_UNPACK_BUFFER, 4*width*height, nil, gl.STREAM_DRAW)
+		gl.BindBuffer(gl.PIXEL_UNPACK_BUFFER, 0)
+		bf = buffer(b)
+		return nil
+	})
+	return bf
+}
+
+func (c *context) mapPixelBuffer(buffer buffer) unsafe.Pointer {
+	var ptr unsafe.Pointer
+	_ = c.t.Call(func() error {
+		gl.BindBuffer(gl.PIXEL_UNPACK_BUFFER, uint32(buffer))
+		ptr = gl.MapBuffer(gl.PIXEL_UNPACK_BUFFER, gl.WRITE_ONLY)
+		gl.BindBuffer(gl.PIXEL_UNPACK_BUFFER, 0)
+		return nil
+	})
+	return ptr
+}
+
+func (c *context) unmapPixelBuffer(buffer buffer, t textureNative, width, height int) {
+	_ = c.t.Call(func() error {
+		gl.BindBuffer(gl.PIXEL_UNPACK_BUFFER, uint32(buffer))
+		gl.UnmapBuffer(gl.PIXEL_UNPACK_BUFFER)
+		return nil
+	})
+	c.bindTexture(t)
+	_ = c.t.Call(func() error {
+		gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, int32(width), int32(height), 0, gl.RGBA, gl.UNSIGNED_BYTE, nil)
+		gl.BindBuffer(gl.PIXEL_UNPACK_BUFFER, 0)
+		return nil
+	})
+}

internal/graphicsdriver/opengl/context_js.go

@@ -470,3 +470,7 @@ func (c *context) flush() {
 func (c *context) needsRestoring() bool {
 	return !web.IsMobileBrowser()
 }
+
+func (c *context) canUsePBO() bool {
+	return false
+}

internal/graphicsdriver/opengl/gl/package.go

@@ -20,6 +20,8 @@ const (
 	ARRAY_BUFFER         = 0x8892
 	ELEMENT_ARRAY_BUFFER = 0x8893
 	DYNAMIC_DRAW         = 0x88E8
+	STREAM_DRAW          = 0x88E0
+	PIXEL_UNPACK_BUFFER  = 0x88EC
 	SHORT                = 0x1402
 	FLOAT                = 0x1406
 
@@ -56,6 +58,7 @@ const (
 	UNSIGNED_BYTE        = 0x1401
 	UNSIGNED_SHORT       = 0x1403
 	VERTEX_SHADER        = 0x8B31
+	WRITE_ONLY           = 0x88B9
 )
 
 // Init initializes the OpenGL bindings by loading the function pointers (for

internal/graphicsdriver/opengl/gl/package_notwindows.go

@@ -144,6 +144,7 @@ package gl
 // typedef GLboolean  (APIENTRYP GPISPROGRAM)(GLuint  program);
 // typedef GLboolean  (APIENTRYP GPISTEXTURE)(GLuint  texture);
 // typedef void  (APIENTRYP GPLINKPROGRAM)(GLuint  program);
+// typedef void * (APIENTRYP GPMAPBUFFER)(GLenum  target, GLenum  access);
 // typedef void  (APIENTRYP GPPIXELSTOREI)(GLenum  pname, GLint  param);
 // typedef void  (APIENTRYP GPREADPIXELS)(GLint  x, GLint  y, GLsizei  width, GLsizei  height, GLenum  format, GLenum  type, void * pixels);
 // typedef void  (APIENTRYP GPSHADERSOURCE)(GLuint  shader, GLsizei  count, const GLchar *const* string, const GLint * length);
@@ -155,6 +156,7 @@ package gl
 // typedef void  (APIENTRYP GPUNIFORM2FV)(GLint  location, GLsizei  count, const GLfloat * value);
 // typedef void  (APIENTRYP GPUNIFORM4FV)(GLint  location, GLsizei  count, const GLfloat * value);
 // typedef void  (APIENTRYP GPUNIFORMMATRIX4FV)(GLint  location, GLsizei  count, GLboolean  transpose, const GLfloat * value);
+// typedef GLboolean  (APIENTRYP GPUNMAPBUFFER)(GLenum  target);
 // typedef void  (APIENTRYP GPUSEPROGRAM)(GLuint  program);
 // typedef void  (APIENTRYP GPVERTEXATTRIBPOINTER)(GLuint  index, GLint  size, GLenum  type, GLboolean  normalized, GLsizei  stride, const uintptr_t pointer);
 // typedef void  (APIENTRYP GPVIEWPORT)(GLint  x, GLint  y, GLsizei  width, GLsizei  height);
@@ -303,6 +305,9 @@ package gl
 // static void  glowLinkProgram(GPLINKPROGRAM fnptr, GLuint  program) {
 //   (*fnptr)(program);
 // }
+// static void * glowMapBuffer(GPMAPBUFFER fnptr, GLenum  target, GLenum  access) {
+//   return (*fnptr)(target, access);
+// }
 // static void  glowPixelStorei(GPPIXELSTOREI fnptr, GLenum  pname, GLint  param) {
 //   (*fnptr)(pname, param);
 // }
@@ -336,6 +341,9 @@ package gl
 // static void  glowUniformMatrix4fv(GPUNIFORMMATRIX4FV fnptr, GLint  location, GLsizei  count, GLboolean  transpose, const GLfloat * value) {
 //   (*fnptr)(location, count, transpose, value);
 // }
+// static GLboolean  glowUnmapBuffer(GPUNMAPBUFFER fnptr, GLenum  target) {
+//   return (*fnptr)(target);
+// }
 // static void  glowUseProgram(GPUSEPROGRAM fnptr, GLuint  program) {
 //   (*fnptr)(program);
 // }
@@ -401,6 +409,7 @@ var (
 	gpIsProgram                   C.GPISPROGRAM
 	gpIsTexture                   C.GPISTEXTURE
 	gpLinkProgram                 C.GPLINKPROGRAM
+	gpMapBuffer                   C.GPMAPBUFFER
 	gpPixelStorei                 C.GPPIXELSTOREI
 	gpReadPixels                  C.GPREADPIXELS
 	gpShaderSource                C.GPSHADERSOURCE
@@ -412,6 +421,7 @@ var (
 	gpUniform2fv                  C.GPUNIFORM2FV
 	gpUniform4fv                  C.GPUNIFORM4FV
 	gpUniformMatrix4fv            C.GPUNIFORMMATRIX4FV
+	gpUnmapBuffer                 C.GPUNMAPBUFFER
 	gpUseProgram                  C.GPUSEPROGRAM
 	gpVertexAttribPointer         C.GPVERTEXATTRIBPOINTER
 	gpViewport                    C.GPVIEWPORT
@@ -616,6 +626,11 @@ func LinkProgram(program uint32) {
 	C.glowLinkProgram(gpLinkProgram, (C.GLuint)(program))
 }
 
+func MapBuffer(target uint32, access uint32) unsafe.Pointer {
+	ret := C.glowMapBuffer(gpMapBuffer, (C.GLenum)(target), (C.GLenum)(access))
+	return (unsafe.Pointer)(ret)
+}
+
 func PixelStorei(pname uint32, param int32) {
 	C.glowPixelStorei(gpPixelStorei, (C.GLenum)(pname), (C.GLint)(param))
 }
@@ -660,6 +675,11 @@ func UniformMatrix4fv(location int32, count int32, transpose bool, value *float3
 	C.glowUniformMatrix4fv(gpUniformMatrix4fv, (C.GLint)(location), (C.GLsizei)(count), (C.GLboolean)(boolToInt(transpose)), (*C.GLfloat)(unsafe.Pointer(value)))
 }
 
+func UnmapBuffer(target uint32) bool {
+	ret := C.glowUnmapBuffer(gpUnmapBuffer, (C.GLenum)(target))
+	return ret == TRUE
+}
+
 func UseProgram(program uint32) {
 	C.glowUseProgram(gpUseProgram, (C.GLuint)(program))
 }
@@ -813,6 +833,10 @@ func InitWithProcAddrFunc(getProcAddr func(name string) unsafe.Pointer) error {
 	if gpLinkProgram == nil {
 		return errors.New("glLinkProgram")
 	}
+	gpMapBuffer = (C.GPMAPBUFFER)(getProcAddr("glMapBuffer"))
+	if gpMapBuffer == nil {
+		return errors.New("glMapBuffer")
+	}
 	gpPixelStorei = (C.GPPIXELSTOREI)(getProcAddr("glPixelStorei"))
 	if gpPixelStorei == nil {
 		return errors.New("glPixelStorei")
@@ -857,6 +881,10 @@ func InitWithProcAddrFunc(getProcAddr func(name string) unsafe.Pointer) error {
 	if gpUniformMatrix4fv == nil {
 		return errors.New("glUniformMatrix4fv")
 	}
+	gpUnmapBuffer = (C.GPUNMAPBUFFER)(getProcAddr("glUnmapBuffer"))
+	if gpUnmapBuffer == nil {
+		return errors.New("glUnmapBuffer")
+	}
 	gpUseProgram = (C.GPUSEPROGRAM)(getProcAddr("glUseProgram"))
 	if gpUseProgram == nil {
 		return errors.New("glUseProgram")

internal/graphicsdriver/opengl/gl/package_windows.go

@@ -58,6 +58,7 @@ var (
 	gpIsProgram                   uintptr
 	gpIsTexture                   uintptr
 	gpLinkProgram                 uintptr
+	gpMapBuffer                   uintptr
 	gpPixelStorei                 uintptr
 	gpReadPixels                  uintptr
 	gpShaderSource                uintptr
@@ -69,6 +70,7 @@ var (
 	gpUniform2fv                  uintptr
 	gpUniform4fv                  uintptr
 	gpUniformMatrix4fv            uintptr
+	gpUnmapBuffer                 uintptr
 	gpUseProgram                  uintptr
 	gpVertexAttribPointer         uintptr
 	gpViewport                    uintptr
@@ -269,6 +271,11 @@ func IsTexture(texture uint32) bool {
 	return ret != 0
 }
 
+func MapBuffer(target uint32, access uint32) unsafe.Pointer {
+	ret, _, _ := syscall.Syscall(gpMapBuffer, 2, uintptr(target), uintptr(access), 0)
+	return unsafe.Pointer(ret)
+}
+
 func LinkProgram(program uint32) {
 	syscall.Syscall(gpLinkProgram, 1, uintptr(program), 0, 0)
 }
@@ -317,6 +324,11 @@ func UniformMatrix4fv(location int32, count int32, transpose bool, value *float3
 	syscall.Syscall6(gpUniformMatrix4fv, 4, uintptr(location), uintptr(count), boolToUintptr(transpose), uintptr(unsafe.Pointer(value)), 0, 0)
 }
 
+func UnmapBuffer(target uint32) bool {
+	ret, _, _ := syscall.Syscall(gpUnmapBuffer, 1, uintptr(target), 0, 0)
+	return ret != 0
+}
+
 func UseProgram(program uint32) {
 	syscall.Syscall(gpUseProgram, 1, uintptr(program), 0, 0)
 }
@@ -466,6 +478,10 @@ func InitWithProcAddrFunc(getProcAddr func(name string) uintptr) error {
 	if gpIsTexture == 0 {
 		return errors.New("glIsTexture")
 	}
+	gpMapBuffer = getProcAddr("glMapBuffer")
+	if gpMapBuffer == 0 {
+		return errors.New("glMapBuffer")
+	}
 	gpLinkProgram = getProcAddr("glLinkProgram")
 	if gpLinkProgram == 0 {
 		return errors.New("glLinkProgram")
@@ -514,6 +530,10 @@ func InitWithProcAddrFunc(getProcAddr func(name string) uintptr) error {
 	if gpUniformMatrix4fv == 0 {
 		return errors.New("glUniformMatrix4fv")
 	}
+	gpUnmapBuffer = getProcAddr("glUnmapBuffer")
+	if gpUnmapBuffer == 0 {
+		return errors.New("glUnmapBuffer")
+	}
 	gpUseProgram = getProcAddr("glUseProgram")
 	if gpUseProgram == 0 {
 		return errors.New("glUseProgram")

internal/graphicsdriver/opengl/image.go

@@ -22,6 +22,7 @@ type Image struct {
 	driver        *Driver
 	textureNative textureNative
 	framebuffer   *framebuffer
+	pbo           buffer
 	width         int
 	height        int
 	screen        bool
@@ -32,6 +33,10 @@ func (i *Image) IsInvalidated() bool {
 }
 
 func (i *Image) Dispose() {
+	thePBOState.ensurePBOUnmapped()
+	if i.pbo != *new(buffer) {
+		i.driver.context.deleteBuffer(i.pbo)
+	}
 	if i.framebuffer != nil {
 		i.framebuffer.delete(&i.driver.context)
 	}
@@ -53,6 +58,7 @@ func (i *Image) setViewport() error {
 }
 
 func (i *Image) Pixels() ([]byte, error) {
+	thePBOState.ensurePBOUnmapped()
 	if err := i.ensureFramebuffer(); err != nil {
 		return nil, err
 	}
@@ -96,7 +102,13 @@ func (i *Image) ReplacePixels(p []byte, x, y, width, height int) {
 		i.driver.context.flush()
 	}
 	i.driver.drawCalled = false
+
+	if canUsePBO {
+		thePBOState.mapPBOIfNecessary(i)
+		thePBOState.draw(p, x, y, width, height)
+	} else {
 		i.driver.context.texSubImage2D(i.textureNative, p, x, y, width, height)
+	}
 }
 
 func (i *Image) SetAsSource() {

internal/graphicsdriver/opengl/pbo_desktop.go

@@ -0,0 +1,87 @@
+// Copyright 2019 The Ebiten Authors
+//
+// 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.
+
+// +build darwin freebsd linux windows
+// +build !js
+// +build !android
+// +build !ios
+
+package opengl
+
+import (
+	"reflect"
+	"runtime"
+	"unsafe"
+
+	"github.com/hajimehoshi/ebiten/internal/graphics"
+)
+
+const canUsePBO = true
+
+type pboState struct {
+	image     *Image
+	mappedPBO unsafe.Pointer
+}
+
+var thePBOState pboState
+
+func (s *pboState) mapPBOIfNecessary(img *Image) {
+	if s.image == img {
+		return
+	}
+
+	s.ensurePBOUnmapped()
+
+	if img.pbo == *new(buffer) {
+		w, h := graphics.InternalImageSize(img.width), graphics.InternalImageSize(img.height)
+		img.pbo = img.driver.context.newPixelBufferObject(w, h)
+	}
+	s.image = img
+	s.mappedPBO = img.driver.context.mapPixelBuffer(img.pbo)
+
+	if s.mappedPBO == nil {
+		panic("opengl: mapPixelBuffer failed")
+	}
+}
+
+func (s *pboState) draw(pix []byte, x, y, width, height int) {
+	w, h := graphics.InternalImageSize(s.image.width), graphics.InternalImageSize(s.image.height)
+
+	var mapped []byte
+	sh := (*reflect.SliceHeader)(unsafe.Pointer(&mapped))
+	sh.Data = uintptr(s.mappedPBO)
+	sh.Len = 4 * w * h
+	sh.Cap = 4 * w * h
+
+	stride := 4 * w
+	offset := 4 * (y*w + x)
+	for j := 0; j < height; j++ {
+		copy(mapped[offset+stride*j:offset+stride*j+4*width], pix[4*width*j:4*width*(j+1)])
+	}
+
+	runtime.KeepAlive(mapped)
+}
+
+func (s *pboState) ensurePBOUnmapped() {
+	if s.mappedPBO == nil {
+		return
+	}
+
+	i := s.image
+	w, h := graphics.InternalImageSize(i.width), graphics.InternalImageSize(i.height)
+	i.driver.context.unmapPixelBuffer(i.pbo, i.textureNative, w, h)
+
+	s.image = nil
+	s.mappedPBO = nil
+}

internal/graphicsdriver/opengl/pbo_notdesktop.go

@@ -0,0 +1,35 @@
+// Copyright 2019 The Ebiten Authors
+//
+// 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.
+
+// +build js android ios
+
+package opengl
+
+const canUsePBO = false
+
+type pboState struct{}
+
+var thePBOState pboState
+
+func (s *pboState) mapPBOIfNecessary(img *Image) {
+	panic("opengl: PBO is not available in this environment")
+}
+
+func (s *pboState) draw(pix []byte, x, y, width, height int) {
+	panic("opengl: PBO is not available in this environment")
+}
+
+func (s *pboState) ensurePBOUnmapped() {
+	// Do nothing
+}

internal/graphicsdriver/opengl/program.go

@@ -265,6 +265,8 @@ func (d *Driver) useProgram(mode driver.CompositeMode, colorM *affine.ColorM, fi
 		panic("source image is not set")
 	}
 
+	thePBOState.ensurePBOUnmapped()
+
 	if err := destination.setViewport(); err != nil {
 		return err
 	}