ios - 执行 CMSampleBuffer OpenGL Swift 的平移/旋转

Question

我正在尝试读取 AVAsset 并在 Assets 的每一帧中使用 GPU 进行平移或旋转操作。

根据我的研究，我找到了一种将 CMSampleBuffer 转换为 GPU 纹理的方法。我正在使用以下方法来做到这一点:

func texture(fromBuffer sampleBuffer: CMSampleBuffer) -> GLuint {
        var texture : GLuint = 0
        glGenTextures(1, &texture)
        glBindTexture(GLenum(GL_TEXTURE_2D), texture)
        glTexParameteri(GLenum(GL_TEXTURE_2D), GLenum(GL_TEXTURE_MIN_FILTER), GL_LINEAR)
        glTexParameteri(GLenum(GL_TEXTURE_2D), GLenum(GL_TEXTURE_MAG_FILTER), GL_LINEAR)
        glTexParameteri(GLenum(GL_TEXTURE_2D), GLenum(GL_TEXTURE_WRAP_S), GL_CLAMP_TO_EDGE)
        glTexParameteri(GLenum(GL_TEXTURE_2D), GLenum(GL_TEXTURE_WRAP_T), GL_CLAMP_TO_EDGE)

        if let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) {
            CVPixelBufferLockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
            let width = CVPixelBufferGetWidth(pixelBuffer)
            let height = CVPixelBufferGetHeight(pixelBuffer)
            glTexImage2D(GLenum(GL_TEXTURE_2D), 0, GL_RGBA, GLsizei(width), GLsizei(height), 0, GLenum(GL_BGRA), GLenum(GL_UNSIGNED_BYTE), CVPixelBufferGetBaseAddress(pixelBuffer))
            CVPixelBufferUnlockBaseAddress(pixelBuffer, CVPixelBufferLockFlags(rawValue: 0))
        }
        return texture
}

现在我需要用这个纹理做我想要的操作，但这是我卡住的地方。从一个 Objc 示例中，我翻译了一个函数，该函数接收一个纹理作为参数并返回一个 CGImage。

方法如下:

func processTexture(_ texture: GLuint, width: Int, height: Int) -> CGImage? {
        var newImage : CGImage?
        var frameBuffer : GLuint = 0

        glGenFramebuffers(1, &frameBuffer)
        glBindFramebuffer(GLenum(GL_FRAMEBUFFER), frameBuffer)

        var colorRenderbuffer : GLuint = 0


        glGenRenderbuffers(1, &colorRenderbuffer)
        glBindRenderbuffer(GLenum(GL_RENDERBUFFER), colorRenderbuffer)
        glRenderbufferStorage(GLenum(GL_RENDERBUFFER), GLenum(GL_RGBA8_OES), GLsizei(width), GLsizei(height))
        glFramebufferRenderbuffer(GLenum(GL_FRAMEBUFFER), GLenum(GL_COLOR_ATTACHMENT0), GLenum(GL_RENDERBUFFER), colorRenderbuffer)

        let status = glCheckFramebufferStatus(GLenum(GL_FRAMEBUFFER))
        if status != GLenum(GL_FRAMEBUFFER_COMPLETE) {
            print("ERROR")
        } else {
            glViewport(0, 0, GLsizei(width), GLsizei(height))
            glClearColor(0.0, 0.0, 0.0, 1.0)
            glClear(GLbitfield(GL_COLOR_BUFFER_BIT))

            let data = UnsafeMutablePointer<Data>.allocate(capacity: width * height * 4)

            glReadPixels(0, 0, GLsizei(width), GLsizei(height), GLenum(GL_RGBA), GLenum(GL_UNSIGNED_BYTE), data)

            let cgDataProviderReleaseDataCallback: CGDataProviderReleaseDataCallback = { (info: UnsafeMutableRawPointer?, data: UnsafeRawPointer, size: Int) -> () in
                return
            }

            if let dataProvider = CGDataProvider(dataInfo: nil, data: data, size: width * height * 4, releaseData: cgDataProviderReleaseDataCallback) {
                let colorSpace = CGColorSpaceCreateDeviceRGB()
                newImage = CGImage(width: width, height: height, bitsPerComponent: 8, bitsPerPixel: 32, bytesPerRow: width * 4, space: colorSpace, bitmapInfo:  .byteOrder32Big, provider: dataProvider, decode: nil, shouldInterpolate: true, intent: .defaultIntent)
            }
        }
        return newImage
    }

但是我找不到在哪里可以对这段代码进行平移和旋转操作，或者我该如何做。

很高兴，如果有人已经在 iOS 上使用过 OpenGL，可以给我帮助，甚至可以告诉我在哪里可以找到此类操作的示例。

Answer 1

您需要有一个带有纹理的四边形(两个三角形)。您对该四边形应用变换(旋转、平移、缩放等)。查看 GPUImage 库源代码。