16.7内建函数
HLSL有一个丰富的内建函数的集合，它们对3D图形来说非常有用。下表是一个删减了的列表，注意：要得到更多的参考，可以参看DirectX文档中内建HLSL函数的完整列表。
以下表格中，//<variable>//表示变量variable的模（例如向量的绝对值）。
|
函数 |
描述 |
|
abs(x) |
返回 |x| |
|
ceil(x) |
返回 ≥ x 的最小整数 |
|
clamp(x, a, b) |
Clamps x to the range [a, b] and returns the result. |
|
cross(u, v) |
返回 u × v（叉积） |
|
degrees(x) |
转换 x 从弧度到角度 |
|
determinant(M) |
返回矩阵M的行列式det(M) |
|
distance(u, v) |
返回u点和v点之间的距离||v - u|| |
|
dot(u, v) |
返回 u · v（点积） |
|
floor(x) |
返回 ≤ x 的最大整数 |
|
length(v) |
返回 ||v|| |
|
lerp(u, v, t) |
在u和v之间线性插值，参数 t 在[0, 1 ]之间变化。 |
|
log(x) |
返回 ln(x) |
|
log10(x) |
返回 log10(x) |
|
log2(x) |
返回 log2(x) |
|
max(x, y) |
如果x ≥ y，则返回 x；否则返回 y |
|
min(x, y) |
如果 x ≤ y，返回x；否则返回 y |
|
mul(M, N) |
返回矩阵乘积 MN. 注意：矩阵乘积必须是已定义的. 如果M是一个向量，它被作为一个行向量，则向量－矩阵（vector-matrix）乘法是已定义的。类似的,如果N 是一个向量，他被作为一个列向量，则矩阵－向量（matrix-vector）乘法是已定义的。 |
|
normalize(v) |
返回 v/∥v∥ |
|
pow(b, n) |
返回 bn |
|
radians(x) |
转换 x 从 角度 到 弧度 |
|
reflect(v, n) |
给定向量v和表面法线n，计算其反射向量 |
|
refract(v,n, eta) |
给定向量v、表面法线n和两种材质的两个索引的比率eta，计算其折射向量. 翻看一下物理书中Snell的规则或者在互联网上搜索一下关于refraction（反射）的信息 |
|
rsqrt(x) |
返回x的平方根的倒数 |
|
saturate(x) |
返回clamp(x, 0.0, 1.0) |
|
sin(x) |
返回x的正弦,其中x单位为弧度 |
|
sincos(in x, out s, out c) |
返回x的正弦和余弦，其中x单位为弧度 |
|
sqrt(x) |
返回x的平方根 |
|
tan(x) |
返回x的正切,其中 x 单位为弧度 |
|
transpose(M) |
返回M的转置 |
abs (Direct3D 9 HLSL)
Computes the absolute value of each component.
Syntax
| ret abs(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float, int | any |
| ret | out | same as input x | same as input x | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_1_4 |
ceil (Direct3D 9 HLSL)
Returns the smallest integer which is greater than or equal to x.
Syntax
| ret ceil(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
clamp (Direct3D 9 HLSL)
Clamps x to the range [min, max].
Syntax
| ret clamp(x, min, max) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float, int | any |
| min | in | same as input x | float, int | same dimension(s) as input x |
| max | in | same as input x | float, int | same dimension(s) as input x |
| ret | out | same as input x | float, int | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_1_4 |
cross (Direct3D 9 HLSL)
Returns the cross product of two 3D vectors.
Syntax
| ret cross(x, y) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | vector | float | 3 |
| y | in | vector | float | 3 |
| ret | out | vector | float | 3 |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_1_4 |
degrees (Direct3D 9 HLSL)
Converts x from radians to degrees.
Syntax
| ret degrees(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
determinant (Direct3D 9 HLSL)
Returns the determinant of the square matrix m.
Syntax
| ret determinant(m) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| m | in | matrix | float | any (number of rows = number of columns) |
| ret | out | scalar | float | 1 |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_1_4 |
distance (Direct3D 9 HLSL)
Returns the distance between two points x and y.
Syntax
| ret distance(x, y) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | vector | float | any |
| y | in | vector | float | same dimension(s) as input x |
| ret | out | scalar | float | 1 |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
dot (Direct3D 9 HLSL)
Returns the • product of two vectors, x and y.
Syntax
| ret dot(x, y) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | vector | float, int | any |
| y | in | vector | float, int | same dimensions(s) as input x |
| ret | out | scalar | float, int | 1 |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_1_1 |
floor (Direct3D 9 HLSL)
Returns the greatest integer which is less than or equal to x.
Syntax
| ret floor(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
length (Direct3D 9 HLSL)
Returns the length of the vector x.
Syntax
| ret length(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | vector | float | any |
| ret | out | scalar | float | 1 |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
lerp (Direct3D 9 HLSL)
Returns x + s(y - x). This linearly interpolates between x and y, such that the return value is x when s is 0, and y when s is 1.
Syntax
| ret lerp(x, y, s) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| y | in | same as input x | float | same dimension(s) as input x |
| s | in | same as input x | float | same dimension(s) as input x |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_1_4 |
log (Direct3D 9 HLSL)
Returns the base-e logarithm of x. If x is negative, the function returns indefinite. If x is 0, the function returns +INF.
Syntax
| ret log(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
log10 (Direct3D 9 HLSL)
Returns the base-10 logarithm of x. If x is negative, the function returns indefinite. If x is 0, the function returns +INF.
Syntax
| ret log10(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |
log2 (Direct3D 9 HLSL)
Returns the base-2 logarithm of x. If x is negative, the function returns indefinite. If x is 0, the function returns +INF.
Syntax
| ret log2(x) |
|---|
Where:
| Name | In/Out | Template Type | Component Type | Size |
|---|---|---|---|---|
| x | in | scalar, vector, or matrix | float | any |
| ret | out | same as input x | float | same dimension(s) as input x |
Minimum Shader Version
This intrinsic function is supported in the following (or above) shader versions:
| Vertex Shader | Pixel Shader |
|---|---|
| vs_1_1 | ps_2_0 |