## C Specification

The source and destination color and alpha blending factors are selected from the enum:

typedef enum VkBlendFactor {
VK_BLEND_FACTOR_ZERO = 0,
VK_BLEND_FACTOR_ONE = 1,
VK_BLEND_FACTOR_SRC_COLOR = 2,
VK_BLEND_FACTOR_ONE_MINUS_SRC_COLOR = 3,
VK_BLEND_FACTOR_DST_COLOR = 4,
VK_BLEND_FACTOR_ONE_MINUS_DST_COLOR = 5,
VK_BLEND_FACTOR_SRC_ALPHA = 6,
VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA = 7,
VK_BLEND_FACTOR_DST_ALPHA = 8,
VK_BLEND_FACTOR_ONE_MINUS_DST_ALPHA = 9,
VK_BLEND_FACTOR_CONSTANT_COLOR = 10,
VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_COLOR = 11,
VK_BLEND_FACTOR_CONSTANT_ALPHA = 12,
VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_ALPHA = 13,
VK_BLEND_FACTOR_SRC_ALPHA_SATURATE = 14,
VK_BLEND_FACTOR_SRC1_COLOR = 15,
VK_BLEND_FACTOR_ONE_MINUS_SRC1_COLOR = 16,
VK_BLEND_FACTOR_SRC1_ALPHA = 17,
VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA = 18,
} VkBlendFactor;

## Description

The semantics of each enum value is described in the table below:

Table 1. Blend Factors
VkBlendFactor RGB Blend Factors (Sr,Sg,Sb) or (Dr,Dg,Db) Alpha Blend Factor (Sa or Da)

VK_BLEND_FACTOR_ZERO

(0,0,0)

0

VK_BLEND_FACTOR_ONE

(1,1,1)

1

VK_BLEND_FACTOR_SRC_COLOR

(Rs0,Gs0,Bs0)

As0

VK_BLEND_FACTOR_ONE_MINUS_SRC_COLOR

(1-Rs0,1-Gs0,1-Bs0)

1-As0

VK_BLEND_FACTOR_DST_COLOR

(Rd,Gd,Bd)

VK_BLEND_FACTOR_ONE_MINUS_DST_COLOR

(1-Rd,1-Gd,1-Bd)

VK_BLEND_FACTOR_SRC_ALPHA

(As0,As0,As0)

As0

VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA

(1-As0,1-As0,1-As0)

1-As0

VK_BLEND_FACTOR_DST_ALPHA

VK_BLEND_FACTOR_ONE_MINUS_DST_ALPHA

VK_BLEND_FACTOR_CONSTANT_COLOR

(Rc,Gc,Bc)

Ac

VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_COLOR

(1-Rc,1-Gc,1-Bc)

1-Ac

VK_BLEND_FACTOR_CONSTANT_ALPHA

(Ac,Ac,Ac)

Ac

VK_BLEND_FACTOR_ONE_MINUS_CONSTANT_ALPHA

(1-Ac,1-Ac,1-Ac)

1-Ac

VK_BLEND_FACTOR_SRC_ALPHA_SATURATE

1

VK_BLEND_FACTOR_SRC1_COLOR

(Rs1,Gs1,Bs1)

As1

VK_BLEND_FACTOR_ONE_MINUS_SRC1_COLOR

(1-Rs1,1-Gs1,1-Bs1)

1-As1

VK_BLEND_FACTOR_SRC1_ALPHA

(As1,As1,As1)

As1

VK_BLEND_FACTOR_ONE_MINUS_SRC1_ALPHA

(1-As1,1-As1,1-As1)

1-As1

In this table, the following conventions are used:

• Rs0,Gs0,Bs0 and As0 represent the first source color R, G, B, and A components, respectively, for the fragment output location corresponding to the color attachment being blended.

• Rs1,Gs1,Bs1 and As1 represent the second source color R, G, B, and A components, respectively, used in dual source blending modes, for the fragment output location corresponding to the color attachment being blended.

• Rd,Gd,Bd and Ad represent the R, G, B, and A components of the destination color. That is, the color currently in the corresponding color attachment for this fragment/sample.

• Rc,Gc,Bc and Ac represent the blend constant R, G, B, and A components, respectively.