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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取大量伪影并使应用程序崩溃。

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。

这就是我必须从 IOSurface 创建纹理（直接来自 Apple 的来源）

// 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。（也来自苹果的来源）

// 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 绘制到屏幕上可以正常工作。将 IOSurface 绘制到另一个我缺少什么？

假设我有纹理 A、B、C 和 DI 想要：

- 在特定区域中将 A 绘制到 C
上， - 在不同区域中将 B 绘制到 C 上（可能与 A 重叠）， - 将 C 绘制
到屏幕上。

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1 回答 1

2

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。

- (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();
}
于 2013-01-25T05:36:15.240 回答