金属中的混合模式

Question

这是我在 OpenGL 中使用的两种混合模式 IOS 中金属的转换是什么

glEnable(GL_BLEND);

glBlendFuncSeparate(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA,GL_ONE,GL_ONE_MINUS_SRC_ALPHA);

glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE, GL_SRC_ALPHA, GL_ONE);

Answer 1

您在渲染管道描述符上配置混合。 我相信您的GL代码的等效配置是：

// glEnable(GL_BLEND)
renderPipelineDescriptor.colorAttachments[0].isBlendingEnabled = true

// glBlendFuncSeparate(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA,GL_ONE,GL_ONE_MINUS_SRC_ALPHA)
renderPipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = .sourceAlpha
renderPipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = .oneMinusSourceAlpha
renderPipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = .one
renderPipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = .oneMinusSourceAlpha

// glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE, GL_SRC_ALPHA, GL_ONE)
renderPipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = .sourceAlpha
renderPipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = .one
renderPipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = .sourceAlpha
renderPipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = .one

Answer 2

    // source: last draw.
    // destination: previous draw.
    // when use UIGraphicsGetCurrentContext() create UIImage from UIColor. alpha will be premultiplied to RGB.
    // RGB = (Source.rgb * Source.a) + (Dest.rgb * (1 - Source.a))
    // A = (Source.a * Source.a) + (Dest.a * (1 - Source.a))
    /*
    pipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = .sourceAlpha
    pipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = .sourceAlpha
    pipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = .oneMinusSourceAlpha
    pipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = .oneMinusSourceAlpha
     */

    // source: last draw.
    // destination: previous draw.
    // when use UIGraphicsGetCurrentContext() create UIImage from UIColor. alpha will be premultiplied to RGB.
    // RGB = (Source.rgb * Source.a) + (Dest.rgb * (1 - Source.a))
    // A = (Source.a * Source.a) + (Dest.a * (1))
    pipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = .sourceAlpha
    pipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = .sourceAlpha
    pipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = .oneMinusSourceAlpha
    pipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = .one