Question

我编写了以下代码来实现将屏幕外渲染添加到金属纹理中的添加剂混合，但是如果启用了Metal API验证则会崩溃：

 validateRenderPassDescriptor:487: failed assertion `Texture at colorAttachment[0] has usage (0x02) which doesn't specify MTLTextureUsageRenderTarget (0x04)'

以下是代码：

  let renderPipelineDescriptorGreen = MTLRenderPipelineDescriptor()
    renderPipelineDescriptorGreen.vertexFunction = vertexFunctionGreen
    renderPipelineDescriptorGreen.fragmentFunction = fragmentFunctionAccumulator
    renderPipelineDescriptorGreen.colorAttachments[0].pixelFormat = .bgra8Unorm
    renderPipelineDescriptorGreen.colorAttachments[0].isBlendingEnabled = true
    renderPipelineDescriptorGreen.colorAttachments[0].rgbBlendOperation = .add
    renderPipelineDescriptorGreen.colorAttachments[0].sourceRGBBlendFactor = .one
    renderPipelineDescriptorGreen.colorAttachments[0].destinationRGBBlendFactor = .one

我想要实现的是加色混合，在OpenGLES中是这样的：

  glBlendEquation(GL_FUNC_ADD);
  glBlendFunc(GL_ONE, GL_ONE);
  glEnable(GL_BLEND);

我的代码有什么问题？

Answer 1

好的，我找到了解决方案。解决方案是在创建纹理时设置纹理使用标志MTLTextureUsage.renderTarget（或者代替使用，shaderRead或shaderWrite创建纹理：

        let textureDescriptor = MTLTextureDescriptor()
        textureDescriptor.textureType = .type3D
        textureDescriptor.pixelFormat = .bgra8Unorm
        textureDescriptor.width = 256
        textureDescriptor.height = 1
        textureDescriptor.usage = .renderTarget

        let texture = device.makeTexture(descriptor: textureDescriptor)

金属API验证崩溃

1 个答案: