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MGLLayer.mm
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//
// Copyright 2019 Le Hoang Quyen. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
#import "MGLLayer+Private.h"
#include <vector>
#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <EGL/eglext_angle.h>
#include <EGL/eglplatform.h>
//#include <common/debug.h>
#include <GLES3/gl3.h>
#include <GLES3/gl3ext.h>
#import "MGLContext+Private.h"
#import "MGLDisplay.h"
namespace
{
constexpr GLchar kBlitVS[] = R"(
attribute vec2 aPosition;
varying mediump vec2 vTexcoords;
void main()
{
gl_Position = vec4(aPosition.x, aPosition.y, 0.0, 1.0);
vTexcoords = 0.5 * (aPosition + vec2(1.0, 1.0));
}
)";
constexpr GLchar kBlitFS[] = R"(
uniform sampler2D uTexture;
varying mediump vec2 vTexcoords;
void main()
{
gl_FragColor = texture2D(uTexture, vTexcoords);
}
)";
template <GLenum State>
class ScopedGLEnable
{
public:
ScopedGLEnable(bool enable)
{
glGetIntegerv(State, &mPrevState);
if (enable)
{
glEnable(State);
}
else
{
glDisable(State);
}
}
~ScopedGLEnable()
{
if (mPrevState)
{
glEnable(State);
}
else
{
glDisable(State);
}
}
private:
GLint mPrevState;
};
template <GLenum Target, GLenum TargetBindingGet, void (*BindFunc)(GLenum, GLuint)>
class ScopedGLBinding
{
public:
ScopedGLBinding(GLuint newObj)
{
glGetIntegerv(TargetBindingGet, &mPrevBoundObj);
BindFunc(Target, newObj);
}
~ScopedGLBinding() { BindFunc(Target, mPrevBoundObj); }
private:
GLint mPrevBoundObj;
};
using ScopedTextureBind = ScopedGLBinding<GL_TEXTURE_2D, GL_TEXTURE_BINDING_2D, glBindTexture>;
using ScopedBufferBind = ScopedGLBinding<GL_ARRAY_BUFFER, GL_ARRAY_BUFFER_BINDING, glBindBuffer>;
using ScopedRenderbufferBind =
ScopedGLBinding<GL_RENDERBUFFER, GL_RENDERBUFFER_BINDING, glBindRenderbuffer>;
using ScopedFBOBind = ScopedGLBinding<GL_FRAMEBUFFER, GL_FRAMEBUFFER_BINDING, glBindFramebuffer>;
using ScopedDrawFBOBind =
ScopedGLBinding<GL_DRAW_FRAMEBUFFER, GL_FRAMEBUFFER_BINDING, glBindFramebuffer>;
using ScopedReadFBOBind =
ScopedGLBinding<GL_READ_FRAMEBUFFER, GL_FRAMEBUFFER_BINDING, glBindFramebuffer>;
class ScopedProgramBind
{
public:
ScopedProgramBind(GLuint program)
{
glGetIntegerv(GL_CURRENT_PROGRAM, &mPrevProgram);
glUseProgram(program);
}
~ScopedProgramBind() { glUseProgram(mPrevProgram); }
private:
GLint mPrevProgram;
};
class ScopedActiveTexture
{
public:
ScopedActiveTexture(GLenum unit)
{
glGetIntegerv(GL_ACTIVE_TEXTURE, &mPrevActiveTexture);
glActiveTexture(unit);
}
~ScopedActiveTexture() { glActiveTexture(mPrevActiveTexture); }
private:
GLint mPrevActiveTexture;
};
struct ScopedVAOBind
{
public:
ScopedVAOBind(GLuint vao)
{
glGetIntegerv(GL_VERTEX_ARRAY_BINDING_OES, &mPrevVAO);
glBindVertexArrayOES(vao);
}
~ScopedVAOBind() { glBindVertexArrayOES(mPrevVAO); }
private:
GLint mPrevVAO;
};
template <void (*DeleteFunc)(GLsizei, const GLuint *)>
class ScopedGLObject
{
public:
ScopedGLObject() : mObject(0) {}
ScopedGLObject(GLuint object) : mObject(object) {}
~ScopedGLObject()
{
if (mObject)
{
DeleteFunc(1, &mObject);
}
mObject = 0;
}
ScopedGLObject &operator=(GLuint object)
{
mObject = object;
return *this;
}
operator GLuint() const { return get(); }
const GLuint &get() const { return mObject; }
GLuint &get() { return mObject; }
private:
GLuint mObject;
};
using ScopedTexture = ScopedGLObject<glDeleteTextures>;
using ScopedRenderbuffer = ScopedGLObject<glDeleteRenderbuffers>;
using ScopedFramebuffer = ScopedGLObject<glDeleteFramebuffers>;
class ScopedViewport
{
public:
ScopedViewport(GLint x, GLint y, GLint width, GLint height)
{
glGetIntegerv(GL_VIEWPORT, mPrevViewport);
glViewport(x, y, width, height);
}
~ScopedViewport()
{
glViewport(mPrevViewport[0], mPrevViewport[1], mPrevViewport[2], mPrevViewport[3]);
}
private:
GLint mPrevViewport[4];
};
class ScopedReadBuffer
{
public:
ScopedReadBuffer(GLint buffer, bool readBufferAvail) : mReadBufferAvail(readBufferAvail)
{
if (!mReadBufferAvail)
{
return;
}
glGetIntegerv(GL_READ_BUFFER, &mPrevReadBuffer);
glReadBuffer(buffer);
}
~ScopedReadBuffer()
{
if (mReadBufferAvail)
{
glReadBuffer(mPrevReadBuffer);
}
}
private:
const bool mReadBufferAvail;
GLint mPrevReadBuffer;
};
class ScopedDrawBuffer
{
public:
ScopedDrawBuffer(GLenum drawbuffer, PFNGLDRAWBUFFERSEXTPROC drawBuffersFunc)
: mDrawBuffersFunc(drawBuffersFunc)
{
if (!mDrawBuffersFunc)
{
return;
}
GLint maxDrawBuffers;
glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxDrawBuffers);
mPrevDrawBuffers.resize(maxDrawBuffers, GL_NONE);
for (int i = 0; i < maxDrawBuffers; ++i)
{
GLint buffer = GL_NONE;
glGetIntegerv(GL_DRAW_BUFFER0 + i, &buffer);
mPrevDrawBuffers[i] = buffer;
}
mDrawBuffersFunc(1, &drawbuffer);
}
~ScopedDrawBuffer()
{
if (!mDrawBuffersFunc)
{
return;
}
GLint currentFBO;
glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, ¤tFBO);
if (currentFBO == 0)
{
mDrawBuffersFunc(1, mPrevDrawBuffers.data());
}
else
{
mDrawBuffersFunc(mPrevDrawBuffers.size(), mPrevDrawBuffers.data());
}
}
private:
std::vector<GLenum> mPrevDrawBuffers;
const PFNGLDRAWBUFFERSEXTPROC mDrawBuffersFunc;
};
void Throw(NSString *msg)
{
[NSException raise:@"MGLSurfaceException" format:@"%@", msg];
}
GLint CompileShader(GLenum target, const GLchar *source, GLuint *shader)
{
GLint logLength, status;
*shader = glCreateShader(target);
const GLchar *sources[] = {source};
glShaderSource(*shader, 1, sources, NULL);
glCompileShader(*shader);
glGetShaderiv(*shader, GL_INFO_LOG_LENGTH, &logLength);
if (logLength > 0)
{
GLchar *log = (GLchar *)malloc(logLength);
glGetShaderInfoLog(*shader, logLength, &logLength, log);
NSLog(@"Shader compile log:\n%s", log);
free(log);
}
glGetShaderiv(*shader, GL_COMPILE_STATUS, &status);
if (status == GL_FALSE)
{
NSLog(@"Failed to compile shader:\n");
NSLog(@"%s", source);
}
return status && *shader;
}
GLint LinkProgram(GLuint program)
{
GLint logLength, status;
glLinkProgram(program);
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logLength);
if (logLength > 0)
{
GLchar *log = (GLchar *)malloc(logLength);
glGetProgramInfoLog(program, logLength, &logLength, log);
NSLog(@"Program link log:\n%s", log);
free(log);
}
glGetProgramiv(program, GL_LINK_STATUS, &status);
if (status == 0)
NSLog(@"Failed to link program %d", program);
return status && program;
}
}
// MGLLayer implementation
@implementation MGLLayer
- (id)init
{
if (self = [super init])
{
[self constructor];
}
return self;
}
- (id)initWithCoder:(NSCoder *)coder
{
if (self = [super initWithCoder:coder])
{
[self constructor];
}
return self;
}
- (void)constructor
{
_drawableColorFormat = MGLDrawableColorFormatRGBA8888;
_drawableDepthFormat = MGLDrawableDepthFormatNone;
_drawableStencilFormat = MGLDrawableStencilFormatNone;
_drawableMultisample = MGLDrawableMultisampleNone;
_display = [MGLDisplay defaultDisplay];
_eglSurface = EGL_NO_SURFACE;
if (1)
{
_metalLayer = [[CAMetalLayer alloc] init];
_metalLayer.frame = self.bounds;
[self addSublayer:_metalLayer];
}
else
{
_legacyGLLayer = [[CALayer alloc] init];
_legacyGLLayer.frame = self.bounds;
[self addSublayer:_legacyGLLayer];
}
}
- (void)dealloc
{
[self releaseSurface];
_display = nil;
}
- (void)setContentsScale:(CGFloat)contentsScale
{
[super setContentsScale:contentsScale];
if (1)
{
_metalLayer.contentsScale = contentsScale;
}
else
{
_legacyGLLayer.contentsScale = contentsScale;
}
}
- (CGSize)drawableSize
{
if (1)
{
if (_metalLayer.drawableSize.width == 0 && _metalLayer.drawableSize.height == 0)
{
[self checkLayerSize];
}
return _metalLayer.drawableSize;
}
return CGSizeMake(self.bounds.size.width * self.contentsScale,
self.bounds.size.height * self.contentsScale);
}
- (BOOL)setCurrentContext:(MGLContext *)context
{
if (eglGetCurrentContext() != context.eglContext ||
eglGetCurrentSurface(EGL_READ) != self.eglSurface ||
eglGetCurrentSurface(EGL_DRAW) != self.eglSurface)
{
if (!eglMakeCurrent(_display.eglDisplay, self.eglSurface, self.eglSurface,
context.eglContext))
{
return NO;
}
}
if (_useOffscreenFBO)
{
GLint currentFBO;
glGetIntegerv(GL_FRAMEBUFFER_BINDING, ¤tFBO);
BOOL offscreenFBOWasBound = currentFBO == _defaultOpenGLFrameBufferID;
if (![self ensureOffscreenFBOCreated])
{
return NO;
}
if (offscreenFBOWasBound)
{
// Draw to offscreen texture instead of eglSurface
glBindFramebuffer(GL_FRAMEBUFFER, _defaultOpenGLFrameBufferID);
}
}
return YES;
}
- (void)bindDefaultFrameBuffer
{
glBindFramebuffer(GL_FRAMEBUFFER, _defaultOpenGLFrameBufferID);
}
- (BOOL)present
{
if (_useOffscreenFBO)
{
if (_blitFramebufferAvail)
{
if (![self blitFBO:_defaultOpenGLFrameBufferID
sourceSize:_offscreenFBOSize
toFBO:0
destinationSize:self.drawableSize
destinationMSAA:NO])
{
return NO;
}
}
else if (![self blitOffscreenTexture:_offscreenTexture toFBO:0])
{
return NO;
}
}
if (!eglSwapBuffers(_display.eglDisplay, self.eglSurface))
{
return NO;
}
[self checkLayerSize];
return YES;
}
- (BOOL)blitFBO:(GLuint)srcFbo
sourceSize:(CGSize)srcSize
toFBO:(GLuint)dstFbo
destinationSize:(CGSize)dstSize
destinationMSAA:(BOOL)destinationMSAA
{
if (srcSize.width != dstSize.width || srcSize.height != dstSize.height || destinationMSAA)
{
// Blit to a temporary texture
ScopedTexture tempTexture;
glGenTextures(1, &tempTexture.get());
ScopedTextureBind bindTexture(tempTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, _offscreenColorUnsizedFormat,
static_cast<GLint>(srcSize.width), static_cast<GLint>(srcSize.height), 0,
_offscreenColorUnsizedFormat, _offscreenColorFormatDataType, 0);
ScopedFramebuffer tempFBO;
glGenFramebuffers(1, &tempFBO.get());
ScopedFBOBind bindFBO(tempFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tempTexture,
0);
if (![self blitFBO:srcFbo
sourceSize:srcSize
toFBO:tempFBO
destinationSize:srcSize
destinationMSAA:NO])
{
return NO;
}
// Draw the temporary texture to destination framebuffer
return [self blitOffscreenTexture:tempTexture toFBO:dstFbo];
}
// Same size blitting
assert(_blitFramebufferAvail);
auto currentCtx = [MGLContext currentContext];
auto currentLayer = [MGLContext currentLayer];
[MGLContext setCurrentContext:_offscreenFBOCreatorContext forLayer:self];
ScopedDrawFBOBind bindDrawFBO(dstFbo);
ScopedReadFBOBind bindReadFBO(srcFbo);
ScopedReadBuffer setReadBuffer(GL_COLOR_ATTACHMENT0, _isGLES3Plus);
ScopedDrawBuffer setDrawBuffer(dstFbo ? GL_COLOR_ATTACHMENT0 : GL_BACK,
_isGLES3Plus ? glDrawBuffers : glDrawBuffersEXT);
ScopedGLEnable<GL_SCISSOR_TEST> disableScissorTest(false);
auto blitFunc = _isGLES3Plus ? glBlitFramebuffer : glBlitFramebufferANGLE;
blitFunc(0, 0, static_cast<GLint>(srcSize.width), static_cast<GLint>(srcSize.height), 0, 0,
static_cast<GLint>(dstSize.width), static_cast<GLint>(dstSize.height),
GL_COLOR_BUFFER_BIT, GL_NEAREST);
BOOL re = glGetError() == GL_NO_ERROR;
[MGLContext setCurrentContext:currentCtx forLayer:currentLayer];
return re;
}
- (BOOL)blitOffscreenTexture:(GLuint)texture toFBO:(GLuint)fbo
{
assert(texture && _offscreenBlitProgram && _offscreenBlitVAO);
auto currentCtx = [MGLContext currentContext];
auto currentLayer = [MGLContext currentLayer];
[MGLContext setCurrentContext:_offscreenFBOCreatorContext forLayer:self];
ScopedFBOBind bindFBO(fbo);
ScopedDrawBuffer setDrawBuffer(fbo ? GL_COLOR_ATTACHMENT0 : GL_BACK,
_isGLES3Plus ? glDrawBuffers : glDrawBuffersEXT);
ScopedProgramBind bindProgram(_offscreenBlitProgram);
ScopedActiveTexture activeTexture(GL_TEXTURE0);
ScopedTextureBind bindTexture(texture);
ScopedVAOBind bindVAO(_offscreenBlitVAO);
ScopedGLEnable<GL_CULL_FACE> disableCull(false);
ScopedGLEnable<GL_DEPTH_TEST> disableDepthTest(false);
ScopedGLEnable<GL_STENCIL_TEST> disableStencilTest(false);
ScopedGLEnable<GL_BLEND> disableBlend(false);
ScopedGLEnable<GL_SCISSOR_TEST> disableScissorTest(false);
ScopedViewport setViewport(0, 0, static_cast<GLint>(_offscreenFBOSize.width),
static_cast<GLint>(_offscreenFBOSize.height));
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
BOOL re = glGetError() == GL_NO_ERROR;
[MGLContext setCurrentContext:currentCtx forLayer:currentLayer];
return re;
}
- (EGLSurface)eglSurface
{
[self ensureSurfaceCreated];
return _eglSurface;
}
- (void)setDrawableProperties:(NSDictionary *)properties {
NSString *colorFormat = properties[kEAGLDrawablePropertyColorFormat];
if ([colorFormat isEqualToString:kEAGLColorFormatRGBA8]) {
_drawableColorFormat = MGLDrawableColorFormatRGBA8888;
} else if ([colorFormat isEqualToString:kEAGLColorFormatRGB565]) {
_drawableColorFormat = MGLDrawableColorFormatRGB565;
} else if ([colorFormat isEqualToString:kEAGLColorFormatSRGBA8]) {
_drawableColorFormat = MGLDrawableColorFormatSRGBA8888;
}
NSNumber *retainedBacking = properties[kEAGLDrawablePropertyRetainedBacking];
if (retainedBacking) {
_retainedBacking = retainedBacking.boolValue;
}
[self releaseSurface];
}
- (void)setDrawableColorFormat:(MGLDrawableColorFormat)drawableColorFormat
{
_drawableColorFormat = drawableColorFormat;
[self releaseSurface];
}
- (void)setDrawableDepthFormat:(MGLDrawableDepthFormat)drawableDepthFormat
{
_drawableDepthFormat = drawableDepthFormat;
[self releaseSurface];
}
- (void)setDrawableStencilFormat:(MGLDrawableStencilFormat)drawableStencilFormat
{
_drawableStencilFormat = drawableStencilFormat;
[self releaseSurface];
}
- (void)setDrawableMultisample:(MGLDrawableMultisample)drawableMultisample
{
_drawableMultisample = drawableMultisample;
if (!1 && _drawableMultisample > 0)
{
// Default backbuffer MSAA is not supported in native GL backend yet.
// Use offscreen MSAA buffer.
_useOffscreenFBO = YES;
}
[self releaseSurface];
}
- (void)setRetainedBacking:(BOOL)retainedBacking
{
// else Metal back-end already supports preserve swap behavior.
_retainedBacking = retainedBacking;
}
- (void)releaseSurface
{
if (_eglSurface == eglGetCurrentSurface(EGL_READ) ||
_eglSurface == eglGetCurrentSurface(EGL_DRAW))
{
eglMakeCurrent(_display.eglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
}
if (_eglSurface != EGL_NO_SURFACE)
{
eglDestroySurface(_display.eglDisplay, _eglSurface);
_eglSurface = EGL_NO_SURFACE;
}
[self releaseOffscreenRenderingResources];
}
- (void)releaseOffscreenRenderingResources
{
if (_defaultOpenGLFrameBufferID)
{
auto oldUseOffscreenFBOFlag = _useOffscreenFBO;
// Avoid the buffer being created again inside setCurrentContext:
_useOffscreenFBO = NO;
auto currentCtx = [MGLContext currentContext];
auto currentLayer = [MGLContext currentLayer];
[MGLContext setCurrentContext:_offscreenFBOCreatorContext];
glDeleteFramebuffers(1, &_defaultOpenGLFrameBufferID);
_defaultOpenGLFrameBufferID = 0;
glDeleteTextures(1, &_offscreenTexture);
_offscreenTexture = 0;
glDeleteRenderbuffers(1, &_offscreenRenderBuffer);
_offscreenRenderBuffer = 0;
glDeleteRenderbuffers(1, &_offscreenDepthStencilBuffer);
_offscreenDepthStencilBuffer = 0;
glDeleteVertexArraysOES(1, &_offscreenBlitVAO);
_offscreenBlitVAO = 0;
glDeleteBuffers(1, &_offscreenBlitVBO);
_offscreenBlitVBO = 0;
glDeleteBuffers(1, &_offscreenBlitProgram);
_offscreenBlitProgram = 0;
[MGLContext setCurrentContext:currentCtx forLayer:currentLayer];
_useOffscreenFBO = oldUseOffscreenFBOFlag;
}
_offscreenFBOSize.width = _offscreenFBOSize.height = 0;
}
- (void)checkLayerSize
{
if (1)
{
// Resize the metal layer
[CATransaction begin];
[CATransaction setValue:(id)kCFBooleanTrue
forKey:kCATransactionDisableActions];
_metalLayer.frame = self.bounds;
_metalLayer.drawableSize =
CGSizeMake(_metalLayer.bounds.size.width * _metalLayer.contentsScale,
_metalLayer.bounds.size.height * _metalLayer.contentsScale);
[CATransaction commit];
}
else
{
_legacyGLLayer.frame = self.bounds;
}
}
- (void)ensureSurfaceCreated
{
if (_eglSurface != EGL_NO_SURFACE)
{
return;
}
[self checkLayerSize];
int red = 8, green = 8, blue = 8, alpha = 8;
int colorSpace;
switch (_drawableColorFormat)
{
case MGLDrawableColorFormatRGBA8888:
// RGB565 default framebuffer is not supported by Metal atm.
// Fallback to RGBA8.
case MGLDrawableColorFormatRGB565:
red = green = blue = alpha = 8;
colorSpace = EGL_GL_COLORSPACE_LINEAR_KHR;
break;
case MGLDrawableColorFormatSRGBA8888:
red = green = blue = alpha = 8;
colorSpace = EGL_GL_COLORSPACE_SRGB_KHR;
break;
default:
abort();
break;
}
// Init surface
std::vector<EGLint> surfaceAttribs = {
EGL_RED_SIZE, red,
EGL_GREEN_SIZE, green,
EGL_BLUE_SIZE, blue,
EGL_ALPHA_SIZE, alpha,
EGL_DEPTH_SIZE, _useOffscreenFBO ? 0 : _drawableDepthFormat,
EGL_STENCIL_SIZE, _useOffscreenFBO ? 0 : _drawableStencilFormat,
EGL_SAMPLE_BUFFERS, 0,
EGL_SAMPLES, _useOffscreenFBO ? EGL_DONT_CARE : _drawableMultisample,
};
surfaceAttribs.push_back(EGL_NONE);
EGLConfig config;
EGLint numConfigs;
if (!eglChooseConfig(_display.eglDisplay, surfaceAttribs.data(), &config, 1, &numConfigs) ||
numConfigs < 1)
{
Throw(@"Failed to call eglChooseConfig()");
}
EGLint creationAttribs[] = {EGL_GL_COLORSPACE_KHR, colorSpace, EGL_NONE};
EGLNativeWindowType nativeWindowPtr;
if (1)
{
// If metal layer is available, use it directly
nativeWindowPtr = (__bridge EGLNativeWindowType)_metalLayer;
}
else
{
nativeWindowPtr = (__bridge EGLNativeWindowType)_legacyGLLayer;
}
_eglSurface =
eglCreateWindowSurface(_display.eglDisplay, config, nativeWindowPtr, creationAttribs);
if (_eglSurface == EGL_NO_SURFACE)
{
Throw(@"Failed to call eglCreateWindowSurface()");
}
if (_retainedBacking && !_useOffscreenFBO)
{
eglSurfaceAttrib(_display.eglDisplay, _eglSurface, EGL_SWAP_BEHAVIOR, EGL_BUFFER_PRESERVED);
}
}
- (BOOL)ensureOffscreenFBOCreated
{
assert(eglGetCurrentContext() != EGL_NO_CONTEXT);
ScopedTexture oldOffscreenTexture = 0;
ScopedRenderbuffer oldOffscreenRenderbuffer = 0;
CGSize oldOffscreenSize = _offscreenFBOSize;
if (_offscreenFBOCreatorContext != [MGLContext currentContext] || !
[self verifyOffscreenFBOSize])
{
// We need to copy the old texture to current texture, so backup the offscreen
// texture/buffer value and set those instance variables to zero to avoid the texture/buffer
// being released.
oldOffscreenTexture = _offscreenTexture;
oldOffscreenRenderbuffer = _offscreenRenderBuffer;
oldOffscreenSize = _offscreenFBOSize;
_offscreenTexture = 0;
_offscreenRenderBuffer = 0;
[self releaseOffscreenRenderingResources];
}
if (_defaultOpenGLFrameBufferID)
{
// Already created.
return YES;
}
if (![self createOffscreenRenderingResources])
{
[self releaseOffscreenRenderingResources];
return NO;
}
// Copy old content to new offscreen framebuffer
if (oldOffscreenTexture.get() || oldOffscreenRenderbuffer.get())
{
if (_blitFramebufferAvail)
{
ScopedFramebuffer tempFBO;
glGenFramebuffers(1, &tempFBO.get());
glBindFramebuffer(GL_READ_FRAMEBUFFER, tempFBO);
glFramebufferRenderbuffer(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
oldOffscreenRenderbuffer);
return [self blitFBO:tempFBO
sourceSize:oldOffscreenSize
toFBO:_defaultOpenGLFrameBufferID
destinationSize:_offscreenFBOSize
destinationMSAA:_drawableMultisample];
}
return [self blitOffscreenTexture:oldOffscreenTexture toFBO:_defaultOpenGLFrameBufferID];
}
return YES;
}
- (BOOL)createOffscreenRenderingResources
{
auto version = reinterpret_cast<const char *>(glGetString(GL_VERSION));
auto exts = reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS));
_isGLES3Plus = strstr(version, "OpenGL ES 3") != nullptr;
_drawBuffersAvail = _isGLES3Plus || strstr(exts, "GL_EXT_draw_buffers") != nullptr;
_blitFramebufferAvail = _isGLES3Plus || strstr(exts, "GL_ANGLE_framebuffer_blit") != nullptr;
if (![self createOffscreenBlitVBO])
{
return NO;
}
if (![self createOffscreenBlitProgram])
{
return NO;
}
return [self createOffscreenFBO];
}
- (BOOL)createOffscreenFBO
{
// Clear pending errors
glGetError();
_offscreenFBOCreatorContext = [MGLContext currentContext];
_offscreenFBOSize = self.drawableSize;
glGenFramebuffers(1, &_defaultOpenGLFrameBufferID);
ScopedFBOBind bindFBO(_defaultOpenGLFrameBufferID);
if (_blitFramebufferAvail)
{
if (![self createOffscreenRenderBuffer])
{
return NO;
}
}
else
{
if (![self createOffscreenTexture])
{
return NO;
}
}
if (![self createOffscreenDepthStencilbuffer])
{
return NO;
}
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
// Fatal error
Throw(@"Offscreen texture is not complete");
}
return _defaultOpenGLFrameBufferID && glGetError() == GL_NO_ERROR;
}
- (BOOL)createOffscreenDepthStencilbuffer
{
// Clear pending errors
glGetError();
int depthBits = _drawableDepthFormat;
int stencilBits = _drawableStencilFormat;
if (!depthBits && !stencilBits)
{
// No depth & stencil buffer
return YES;
}
GLenum depthStencilFormat = 0;
if (depthBits && stencilBits)
{
depthStencilFormat = GL_DEPTH24_STENCIL8_OES;
}
else if (depthBits)
{
depthStencilFormat = GL_DEPTH_COMPONENT24_OES;
}
else if (stencilBits)
{
depthStencilFormat = GL_STENCIL_INDEX8;
}
glGenRenderbuffers(1, &_offscreenDepthStencilBuffer);
ScopedRenderbufferBind bindRenderbuffer(_offscreenDepthStencilBuffer);
if (_drawableMultisample)
{
glRenderbufferStorageMultisampleANGLE(GL_RENDERBUFFER, _drawableMultisample,
depthStencilFormat,
static_cast<GLsizei>(_offscreenFBOSize.width),
static_cast<GLsizei>(_offscreenFBOSize.height));
}
else
{
glRenderbufferStorage(GL_RENDERBUFFER, depthStencilFormat,
static_cast<GLsizei>(_offscreenFBOSize.width),
static_cast<GLsizei>(_offscreenFBOSize.height));
}
if (depthBits)
{
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER,
_offscreenDepthStencilBuffer);
}
if (stencilBits)
{
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
_offscreenDepthStencilBuffer);
}
return _offscreenDepthStencilBuffer && glGetError() == GL_NO_ERROR;
}
// Offscreen renderbuffer is used when glBlitFramebuffer is available.
- (BOOL)createOffscreenRenderBuffer
{
assert(_blitFramebufferAvail);
// Clear pending errors
glGetError();
GLenum sizedFormat;
switch (_drawableColorFormat)
{
case MGLDrawableColorFormatRGBA8888:
case MGLDrawableColorFormatRGB565:
sizedFormat = GL_RGBA8_OES;
_offscreenColorUnsizedFormat = GL_RGBA;
_offscreenColorFormatDataType = GL_UNSIGNED_BYTE;
break;
case MGLDrawableColorFormatSRGBA8888:
sizedFormat = GL_SRGB8_ALPHA8_EXT;
_offscreenColorUnsizedFormat = GL_SRGB_ALPHA_EXT;
_offscreenColorFormatDataType = GL_UNSIGNED_BYTE;
break;
default:
abort();
break;
}
glGenRenderbuffers(1, &_offscreenRenderBuffer);
ScopedRenderbufferBind bindRenderbuffer(_offscreenRenderBuffer);
if (_drawableMultisample)
{
glRenderbufferStorageMultisampleANGLE(GL_RENDERBUFFER, _drawableMultisample, sizedFormat,
static_cast<GLsizei>(_offscreenFBOSize.width),
static_cast<GLsizei>(_offscreenFBOSize.height));
}
else
{
glRenderbufferStorage(GL_RENDERBUFFER, sizedFormat,
static_cast<GLsizei>(_offscreenFBOSize.width),
static_cast<GLsizei>(_offscreenFBOSize.height));
}
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
_offscreenRenderBuffer);