C Specification

Logical operations are controlled by the logicOpEnable and logicOp members of VkPipelineColorBlendStateCreateInfo. If logicOpEnable is VK_TRUE, then a logical operation selected by logicOp is applied between each color attachment and the fragment’s corresponding output value, and blending of all attachments is treated as if it were disabled. Any attachments using color formats for which logical operations are not supported simply pass through the color values unmodified. The logical operation is applied independently for each of the red, green, blue, and alpha components. The logicOp is selected from the following operations:

typedef enum VkLogicOp {
    VK_LOGIC_OP_CLEAR = 0,
    VK_LOGIC_OP_AND = 1,
    VK_LOGIC_OP_AND_REVERSE = 2,
    VK_LOGIC_OP_COPY = 3,
    VK_LOGIC_OP_AND_INVERTED = 4,
    VK_LOGIC_OP_NO_OP = 5,
    VK_LOGIC_OP_XOR = 6,
    VK_LOGIC_OP_OR = 7,
    VK_LOGIC_OP_NOR = 8,
    VK_LOGIC_OP_EQUIVALENT = 9,
    VK_LOGIC_OP_INVERT = 10,
    VK_LOGIC_OP_OR_REVERSE = 11,
    VK_LOGIC_OP_COPY_INVERTED = 12,
    VK_LOGIC_OP_OR_INVERTED = 13,
    VK_LOGIC_OP_NAND = 14,
    VK_LOGIC_OP_SET = 15,
} VkLogicOp;

Description

The logical operations supported by Vulkan are summarized in the following table in which

  • ¬ is bitwise invert,

  • is bitwise and,

  • is bitwise or,

  • is bitwise exclusive or,

  • s is the fragment’s Rs0, Gs0, Bs0 or As0 component value for the fragment output corresponding to the color attachment being updated, and

  • d is the color attachment’s R, G, B or A component value:

Table 1. Logical Operations
Mode Operation

VK_LOGIC_OP_CLEAR

0

VK_LOGIC_OP_AND

s ∧ d

VK_LOGIC_OP_AND_REVERSE

s ∧ ¬ d

VK_LOGIC_OP_COPY

s

VK_LOGIC_OP_AND_INVERTED

¬ s ∧ d

VK_LOGIC_OP_NO_OP

d

VK_LOGIC_OP_XOR

s ⊕ d

VK_LOGIC_OP_OR

s ∨ d

VK_LOGIC_OP_NOR

¬ (s ∨ d)

VK_LOGIC_OP_EQUIVALENT

¬ (s ⊕ d)

VK_LOGIC_OP_INVERT

¬ d

VK_LOGIC_OP_OR_REVERSE

s ∨ ¬ d

VK_LOGIC_OP_COPY_INVERTED

¬ s

VK_LOGIC_OP_OR_INVERTED

¬ s ∨ d

VK_LOGIC_OP_NAND

¬ (s ∧ d)

VK_LOGIC_OP_SET

all 1s

The result of the logical operation is then written to the color attachment as controlled by the component write mask, described in Blend Operations.

See Also

Document Notes

For more information, see the Vulkan Specification at URL

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

Copyright (c) 2014-2017 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.