C Specification

The weighting functions p0, p1, and p2 are defined in table Advanced Blend Overlap Modes. In these functions, the A components of the source and destination colors are taken to indicate the portion of the pixel covered by the fragment (source) and the fragments previously accumulated in the pixel (destination). The functions p0, p1, and p2 approximate the relative portion of the pixel covered by the intersection of the source and destination, covered only by the source, and covered only by the destination, respectively.

Possible values of VkPipelineColorBlendAdvancedStateCreateInfoEXT::blendOverlap, specifying the blend overlap functions, are:

typedef enum VkBlendOverlapEXT {
    VK_BLEND_OVERLAP_UNCORRELATED_EXT = 0,
    VK_BLEND_OVERLAP_DISJOINT_EXT = 1,
    VK_BLEND_OVERLAP_CONJOINT_EXT = 2,
    VK_BLEND_OVERLAP_MAX_ENUM_EXT = 0x7FFFFFFF
} VkBlendOverlapEXT;

Description

  • VK_BLEND_OVERLAP_UNCORRELATED_EXT specifies that there is no correlation between the source and destination coverage.

  • VK_BLEND_OVERLAP_CONJOINT_EXT specifies that the source and destination coverage are considered to have maximal overlap.

  • VK_BLEND_OVERLAP_DISJOINT_EXT specifies that the source and destination coverage are considered to have minimal overlap.

Table 1. Advanced Blend Overlap Modes
Overlap Mode Weighting Equations

VK_BLEND_OVERLAP_UNCORRELATED_EXT

\[ \begin{aligned} p_0(A_s,A_d) & = A_sA_d \\ p_1(A_s,A_d) & = A_s(1-A_d) \\ p_2(A_s,A_d) & = A_d(1-A_s) \\ \end{aligned}\]

VK_BLEND_OVERLAP_CONJOINT_EXT

\[ \begin{aligned} p_0(A_s,A_d) & = min(A_s,A_d) \\ p_1(A_s,A_d) & = max(A_s-A_d,0) \\ p_2(A_s,A_d) & = max(A_d-A_s,0) \\ \end{aligned}\]

VK_BLEND_OVERLAP_DISJOINT_EXT

\[ \begin{aligned} p_0(A_s,A_d) & = max(A_s+A_d-1,0) \\ p_1(A_s,A_d) & = min(A_s,1-A_d) \\ p_2(A_s,A_d) & = min(A_d,1-A_s) \\ \end{aligned}\]

See Also

Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright (c) 2014-2019 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.