将 IOSurface 绘制到另一个 IOSurface [英] Draw IOSurfaces to another IOSurface

问题描述

如何将一系列 IOSurfaces 绘制到另一个然后将其绘制到屏幕上?我在 MultiGPU 示例项目中使用了来自苹果的一些源代码，但我设法做的最好的事情是绘制一个白屏或获得大量工件并使应用程序崩溃.

How can I draw a series of IOSurfaces to another then draw it to the screen? I've played around with some source from apple in the MultiGPU sample project, but the best I managed to do is draw a white screen or get tons of artifacts and crash the app.

我对 openGL 很陌生，我不太了解帧缓冲区和纹理的绑定以及它们如何与 IOSurfaces 交互.

I'm very new to openGL and I don't quite understand the binding of framebuffers and textures and how they interact with IOSurfaces.

这是我必须从 IOSurface(直接来自 Apple 的来源)创建纹理的内容

This is what I have to create a texture from an IOSurface (directly from Apple's source)

// Create an IOSurface backed texture
// Create an FBO using the name of this texture and bind the texture to the color attachment of the FBO
- (GLuint)setupIOSurfaceTexture:(IOSurfaceRef)ioSurfaceBuffer {
    GLuint name;
    CGLContextObj cgl_ctx = (CGLContextObj)[[self openGLContext] CGLContextObj];

    glGenTextures(1, &name);

    glBindTexture(GL_TEXTURE_RECTANGLE_EXT, name);
    CGLTexImageIOSurface2D(cgl_ctx, GL_TEXTURE_RECTANGLE_EXT, GL_RGBA, 512, 512, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV,
                ioSurfaceBuffer, 0);
    glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 

    // Generate an FBO using the same name with the same texture bound to it as a render target.

    glBindTexture(GL_TEXTURE_RECTANGLE_EXT, 0);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, name);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_RECTANGLE_EXT, name, 0);

    if(!_depthBufferName) {
        glGenRenderbuffersEXT(1, &_depthBufferName);
        glRenderbufferStorageEXT(GL_TEXTURE_RECTANGLE_EXT, GL_DEPTH, 512, 512);
    }
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_TEXTURE_RECTANGLE_EXT, _depthBufferName);

    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

    return name;
}

我有这段代码可以将表面绘制到屏幕上.(同样来自苹果的消息)

And I have this piece of code to draw the surface to the screen. (Also from Apple's source)

// Fill the view with the IOSurface backed texture 
- (void)textureFromCurrentIOSurface {
    NSRect bounds = [self bounds];
    CGLContextObj cgl_ctx = (CGLContextObj)[[self openGLContext] CGLContextObj];

    // Render quad from our iosurface texture
    glViewport(0, 0, (GLint)bounds.size.width, (GLint)bounds.size.height);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();   
    glOrtho(0.0, (GLfloat)bounds.size.width, 0.0f, (GLfloat)bounds.size.height, -1.0f, 1.0f);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    glBindTexture(GL_TEXTURE_RECTANGLE_EXT, [[NSApp delegate] currentTextureName]); // Grab the texture from the delegate
    glEnable(GL_TEXTURE_RECTANGLE_EXT);
    glTexEnvi(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_ENV_MODE, GL_REPLACE);

    glBegin(GL_QUADS);
    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

    glTexCoord2f(0.0f, 0.0f);
    glVertex2f(0.0f, 0.0f);

    glTexCoord2f(512.0f, 0.0f);
    glVertex2f((GLfloat)bounds.size.width, 0.0f);

    glTexCoord2f(512.0f, 512.0f);
    glVertex2f((GLfloat)bounds.size.width, (GLfloat)bounds.size.height);

    glTexCoord2f(0.0f, 512.0f);
    glVertex2f(0.0f, (GLfloat)bounds.size.height);

    glEnd();

    glDisable(GL_TEXTURE_RECTANGLE_EXT);
}

将单个 IOSurface 绘制到屏幕上时，这可以正常工作.将 IOSurface 绘制到另一个时我缺少什么?

With a single IOSurface being draw to the screen this works fine. What am I missing to draw an IOSurface to another?

假设我有我想要的纹理 A、B、C 和 D:

Assuming I have textures A, B, C, and D I want to:

-在特定区域将A画到C上，
- 将 B 绘制到不同区域的 C 上(可能与 A 重叠)，
- 将 C 绘制到屏幕上.

-Draw A onto C in a specific region,
-Draw B onto C in a different region (may overlap A),
-Draw C to the screen.

推荐答案

我使用以下代码解决了这个问题，但是在绘制之前缩放 IOSurface 存在一些小问题.

I solved the issue using the following code, however there are some minor issues with scaling the IOSurface before drawing.

- (void)renderIOSurface:(IOSurfaceRef)surface toBuffer:(GLuint)buffer atPoint:(CGPoint)point withSize:(CGSize)size {
CGLContextObj cgl_ctx = (CGLContextObj)[[self openGLContext] CGLContextObj];

// Bind framebuffer
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, buffer);

glViewport(0, 0, TEXWIDE, TEXHIGH);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, TEXWIDE, 0.0, TEXHIGH, -1, 1);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();

GLsizei sH  = (GLsizei)IOSurfaceGetHeight(surface);
GLsizei sW   = (GLsizei)IOSurfaceGetWidth(surface);

// Create texture
GLuint name;
glGenTextures(1, &name);
glEnable(GL_TEXTURE_RECTANGLE_EXT);
glBindTexture(GL_TEXTURE_RECTANGLE_EXT, name);
CGLTexImageIOSurface2D(cgl_ctx, GL_TEXTURE_RECTANGLE_EXT, GL_RGBA, sW, sH, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, surface, 0);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//  glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
//  glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glBindTexture(GL_TEXTURE_RECTANGLE_EXT, 0);

//glDisable(GL_BLEND);

glBindTexture(GL_TEXTURE_RECTANGLE_EXT, name);
    glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

glBegin(GL_QUADS);
glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

glTexCoord2f(0.0f, 0.0f);
glVertex2f(point.x, point.y);

glTexCoord2f(sW, 0.0f);
glVertex2f(point.x + size.width, point.y);

glTexCoord2f(sW, sH);
glVertex2f(point.x + size.width, point.y + size.height);

glTexCoord2f(0.0f, sH);
glVertex2f(point.x, point.y + size.height);

glEnd();

//glDisable(GL_TEXTURE_RECTANGLE_EXT);

// Bindback to normal
glBindTexture(GL_TEXTURE_RECTANGLE_EXT, 0);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

// Delete the name texture
glDeleteTextures(1, &name);

//  [[self openGLContext] flushBuffer];
// This flush is necessary to ensure proper behavior if the MT engine is enabled.
//  glFlush();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glFlush();
}

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