Question

如何将一系列IOSurfaces绘制到另一个IOSurfaces然后将其绘制到屏幕上？我在MultiGPU示例项目中玩了一些来自apple的源代码，但我设法做的最好的事情是绘制白屏或获取大量文件并使应用程序崩溃。

我对openGL很新，我不太了解帧缓冲区和纹理的绑定以及它们与IOSurfaces的交互方式。

这就是我必须从IOSurface创建纹理（直接来自Apple的源代码）

// 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;
}

我有这段代码将表面绘制到屏幕上。（也来自Apple的消息来源）

// 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);
}

只有一个IOSurface被绘制到屏幕上，这很好用。我错过了将IOSurface画给另一个人吗？

假设我有纹理A，B，C和D我想：

-Draw A到特定区域的C，
- 将B绘制到不同区域的C上（可能与A重叠），
-Draw C到屏幕。

Answer 1

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();
}

将IOSurfaces绘制到另一个IOSurface

1 个答案: