VkLogicOp

Logical operations are controlled by the logicOpEnable and logicOp members of VkPipelineColorBlendStateCreateInfo. The logicOpEnable state can also be controlled by vkCmdSetLogicOpEnableEXT if graphics pipeline is created with VK_DYNAMIC_STATE_LOGIC_OP_ENABLE_EXT set in VkPipelineDynamicStateCreateInfo::pDynamicStates. The logicOp state can also be controlled by vkCmdSetLogicOpEXT if graphics pipeline is created with VK_DYNAMIC_STATE_LOGIC_OP_EXT set in VkPipelineDynamicStateCreateInfo::pDynamicStates. 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;

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 R_s0, G_s0, B_s0 or A_s0 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:

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