VkLogicOp(3)

# VkLogicOp(3) Manual Page

## Name

VkLogicOp - Framebuffer logical operations

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## 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:

    // Provided by VK_VERSION_1_0
    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

VkPipelineColorBlendStateCreateInfo

## 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

Copyright (c) 2014-2020 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0