編寫Unity Shader時有很多內置函數，在網上查找了一些，把他們記錄了下來，以供大家參考使用
參考網址：http://www.cppblog.com/lai3d/archive/2008/10/23/64889.html

這個是MSDN上的，DirectX Documentation里也有，其實也就是HLSL的內置函數

Intrinsic Functions (DirectX HLSL)

The following table lists the intrinsic functions available in HLSL. Each function has a brief description, and a link to a reference page that has more detail about the input argument and return type.

NameSyntaxDescription

abs	abs(x)	Absolute value (per component).
acos	acos(x)	Returns the arccosine of each component of x.
all	all(x)	Test if all components of x are nonzero.
any	any(x)	Test if any component of x is nonzero.
asfloat	asfloat(x)	Convert the input type to a float.
asin	asin(x)	Returns the arcsine of each component of x.
asint	asint(x)	Convert the input type to an integer.
asuint	asuint(x)	Convert the input type to an unsigned integer.
atan	atan(x)	Returns the arctangent of x.
atan2	atan2(y, x)	Returns the arctangent of of two values (x,y).
ceil	ceil(x)	Returns the smallest integer which is greater than or equal to x.
clamp	clamp(x, min, max)	Clamps x to the range [min, max].
clip	clip(x)	Discards the current pixel, if any component of x is less than zero.
cos	cos(x)	Returns the cosine of x.
cosh	cosh(x)	Returns the hyperbolic cosine of x.
cross	cross(x, y)	Returns the cross product of two 3D vectors.
D3DCOLORtoUBYTE4	D3DCOLORtoUBYTE4(x)	Swizzles and scales components of the 4D vector x to compensate for the lack of UBYTE4 support in some hardware.
ddx	ddx(x)	Returns the partial derivative of x with respect to the screen-space x-coordinate.
ddy	ddy(x)	Returns the partial derivative of x with respect to the screen-space y-coordinate.
degrees	degrees(x)	Converts x from radians to degrees.
determinant	determinant(m)	Returns the determinant of the square matrix m.
distance	distance(x, y)	Returns the distance between two points.
dot	dot(x, y)	Returns the dot product of two vectors.
exp	exp(x)	Returns the base-e exponent.
exp2	exp2(x)	Base 2 exponent (per component).
faceforward	faceforward(n, i, ng)	Returns -n * sign(?(i, ng)).
floor	floor(x)	Returns the greatest integer which is less than or equal to x.
fmod	fmod(x, y)	Returns the floating point remainder of x/y.
frac	frac(x)	Returns the fractional part of x.
frexp	frexp(x, exp)	Returns the mantissa and exponent of x.
fwidth	fwidth(x)	Returns abs(ddx(x)) + abs(ddy(x))
GetRenderTargetSampleCount	GetRenderTargetSampleCount()	Returns the number of render-target samples.
GetRenderTargetSamplePosition	GetRenderTargetSamplePosition(x)	Returns a sample position (x,y) for a given sample index.
isfinite	isfinite(x)	Returns true if x is finite, false otherwise.
isinf	isinf(x)	Returns true if x is +INF or -INF, false otherwise.
isnan	isnan(x)	Returns true if x is NAN or QNAN, false otherwise.
ldexp	ldexp(x, exp)	Returns x * 2exp
length	length(v)	Returns the length of the vector v.
lerp	lerp(x, y, s)	Returns x + s(y - x).
lit	lit(n ? l, n ? h, m)	Returns a lighting vector (ambient, diffuse, specular, 1)
log	log(x)	Returns the base-e logarithm of x.
log10	log10(x)	Returns the base-10 logarithm of x.
log2	log2(x)	Returns the base-2 logarithm of x.
max	max(x, y)	Selects the greater of x and y.
min	min(x, y)	Selects the lesser of x and y.
modf	modf(x, out ip)	Splits the value x into fractional and integer parts.
mul	mul(x, y)	Performs matrix multiplication using x and y.
noise	noise(x)	Generates a random value using the Perlin-noise algorithm.
normalize	normalize(x)	Returns a normalized vector.
pow	pow(x, y)	Returns xy.
radians	radians(x)	Converts x from degrees to radians.
reflect	reflect(i, n)	Returns a reflection vector.
refract	refract(i, n, R)	Returns the refraction vector.
round	round(x)	Rounds x to the nearest integer
rsqrt	rsqrt(x)	Returns 1 / sqrt(x)
saturate	saturate(x)	Clamps x to the range [0, 1]
sign	sign(x)	Computes the sign of x.
sin	sin(x)	Returns the sine of x
sincos	sincos(x, out s, out c)	Returns the sine and cosine of x.
sinh	sinh(x)	Returns the hyperbolic sine of x
smoothstep	smoothstep(min, max, x)	Returns a smooth Hermite interpolation between 0 and 1.
sqrt	sqrt(x)	Square root (per component)
step	step(a, x)	Returns (x >= a) ? 1 : 0
tan	tan(x)	Returns the tangent of x
tanh	tanh(x)	Returns the hyperbolic tangent of x
tex1D	tex1D(s, t)	1D texture lookup.
tex1Dbias	tex1Dbias(s, t)	1D texture lookup with bias.
tex1Dgrad	tex1Dgrad(s, t, ddx, ddy)	1D texture lookup with a gradient.
tex1Dlod	tex1Dlod(s, t)	1D texture lookup with LOD.
tex1Dproj	tex1Dproj(s, t)	1D texture lookup with projective divide.
tex2D	tex2D(s, t)	2D texture lookup.
tex2Dbias	tex2Dbias(s, t)	2D texture lookup with bias.
tex2Dgrad	tex2Dgrad(s, t, ddx, ddy)	2D texture lookup with a gradient.
tex2Dlod	tex2Dlod(s, t)	2D texture lookup with LOD.
tex2Dproj	tex2Dproj(s, t)	2D texture lookup with projective divide.
tex3D	tex3D(s, t)	3D texture lookup.
tex3Dbias	tex3Dbias(s, t)	3D texture lookup with bias.
tex3Dgrad	tex3Dgrad(s, t, ddx, ddy)	3D texture lookup with a gradient.
tex3Dlod	tex3Dlod(s, t)	3D texture lookup with LOD.
tex3Dproj	tex3Dproj(s, t)	3D texture lookup with projective divide.
texCUBE	texCUBE(s, t)	Cube texture lookup.
texCUBEbias	texCUBEbias(s, t)	Cube texture lookup with bias.
texCUBEgrad	texCUBEgrad(s, t, ddx, ddy)	Cube texture lookup with a gradient.
texCUBElod	tex3Dlod(s, t)	Cube texture lookup with LOD.
texCUBEproj	texCUBEproj(s, t)	Cube texture lookup with projective divide.
transpose	transpose(m)	Returns the transpose of the matrix m.
trunc	trunc(x)	Truncates floating-point value(s) to integer value(s)

表 3-1 HLSL內置函數

函數名?????????? ?用法

abs???????????????????????? 計算輸入值的絕對值。

acos??????????????????????? 返回輸入值反余弦值。

all?????????????????????????? 測試非0值。

any???????????????????????? 測試輸入值中的任何非零值。

asin???????????????????????? 返回輸入值的反正弦值。

atan??????????????????????? 返回輸入值的反正切值。

atan2?????????????????????? 返回y/x的反正切值。

ceil???????????????????????? 返回大于或等于輸入值的最小整數。

clamp????????????????????? 把輸入值限制在[min, max]范圍內。

clip???????????????????????? 如果輸入向量中的任何元素小于0，則丟棄當前像素。

cos???????????????????????? 返回輸入值的余弦。

cosh?????????????????????? 返回輸入值的雙曲余弦。

cross????????????????????? 返回兩個3D向量的叉積。

ddx???????????????????????? 返回關于屏幕坐標x軸的偏導數。

ddy???????????????????????? 返回關于屏幕坐標y軸的偏導數。

degrees?????????????????? 弧度到角度的轉換

determinant????????????? 返回輸入矩陣的值。

distance?????????????????? 返回兩個輸入點間的距離。

dot????????????????????????? 返回兩個向量的點積。

exp???????????????????????? 返回以e為底數，輸入值為指數的指數函數值。

exp2?????????????????????? 返回以2為底數，輸入值為指數的指數函數值。

faceforward???????????? 檢測多邊形是否位于正面。

floor?????????????????????? 返回小于等于x的最大整數。

fmod?????????????????????? 返回a / b的浮點余數。

frac??????????????????????? 返回輸入值的小數部分。

frexp?????????????????????? 返回輸入值的尾數和指數

fwidth???????????????????? 返回 abs ( ddx (x) + abs ( ddy(x))。

isfinite???????????????????? 如果輸入值為有限值則返回true，否則返回false。

isinf??????????????????????? 如何輸入值為無限的則返回true。

isnan?????????????????????? 如果輸入值為NAN或QNAN則返回true。

ldexp?????????????????????? frexp的逆運算，返回 x * 2 ^ exp。

len / lenth??????????????? 返回輸入向量的長度。

lerp???????????????????????? 對輸入值進行插值計算。

lit??????????????????????????? 返回光照向量（環境光，漫反射光，鏡面高光，1）。

log????????????????????????? 返回以e為底的對數。

log10????????????????????? 返回以10為底的對數。

log2??????????????????????? 返回以2為底的對數。

max??????????????????????? 返回兩個輸入值中較大的一個。

min???????????????????????? 返回兩個輸入值中較小的一個。

modf?????????????????????? 把輸入值分解為整數和小數部分。

mul???????????????????????? 返回輸入矩陣相乘的積。

normalize???????????????? 返回規范化的向量，定義為 x / length(x)。

pow??????????????????????? 返回輸入值的指定次冪。

radians??????????????????? 角度到弧度的轉換。

reflect???????????????????? 返回入射光線i對表面法線n的反射光線。

refract???????????????????? 返回在入射光線i，表面法線n，折射率為eta下的折射光線v。

round????????????????????? 返回最接近于輸入值的整數。

rsqrt?????????????????????? 返回輸入值平方根的倒數。

saturate?????????????????? 把輸入值限制到[0, 1]之間。

sign??????????????????????? 計算輸入值的符號。

sin????????????????????????? 計算輸入值的正弦值。

sincos???????????????????? 返回輸入值的正弦和余弦值。

sinh??????????????????????? 返回x的雙曲正弦。

smoothstep????????????? 返回一個在輸入值之間平穩變化的插值。

sqrt???????????????????????? 返回輸入值的平方根。

step??????????????????????? 返回（x >= a）? 1 : 0。

tan????????????????????????? 返回輸入值的正切值。

fanh??????????????????????? 返回輸入值的雙曲線切線。

transpose???????????????? 返回輸入矩陣的轉置。

tex1D*??????????????????? 1D紋理查詢。

tex2D*??????????????????? 2D紋理查詢。

tex3D*??????????????????? 3D紋理查詢。

texCUBE*??????????????? 立方紋理查詢。

Intrinsic Functions (DirectX HLSL)

The following table lists the intrinsic functions available in HLSL. Each function has a brief description, and a link to a reference page that has more detail about the input argument and return type.

Name Description Minimum shader model

abs	Absolute value (per component).	11
acos	Returns the arccosine of each component of x.	11
all	Test if all components of x are nonzero.	11
AllMemoryBarrier	Blocks execution of all threads in a group until all memory accesses have been completed.	5
AllMemoryBarrierWithGroupSync	Blocks execution of all threads in a group until all memory accesses have been completed and all threads in the group have reached this call.	5
any	Test if any component of x is nonzero.	11
asdouble	Reinterprets a cast value into a double.	5
asfloat	Convert the input type to a float.	4
asin	Returns the arcsine of each component of x.	11
asint	Convert the input type to an integer.	4
asuint	Reinterprets the bit pattern of a 64-bit type to a uint.	5
asuint	Convert the input type to an unsigned integer.	4
atan	Returns the arctangent of x.	11
atan2	Returns the arctangent of of two values (x,y).	11
ceil	Returns the smallest integer which is greater than or equal to x.	11
clamp	Clamps x to the range [min, max].	11
clip	Discards the current pixel, if any component of x is less than zero.	11
cos	Returns the cosine of x.	11
cosh	Returns the hyperbolic cosine of x.	11
countbits	Counts the number of bits (per component) in the input integer.	5
cross	Returns the cross product of two 3D vectors.	11
D3DCOLORtoUBYTE4	Swizzles and scales components of the 4D vector xto compensate for the lack of UBYTE4 support in some hardware.	11
ddx	Returns the partial derivative of x with respect to the screen-space x-coordinate.	21
ddx_coarse	Computes a low precision partial derivative with respect to the screen-space x-coordinate.	5
ddx_fine	Computes a high precision partial derivative with respect to the screen-space x-coordinate.	5
ddy	Returns the partial derivative of x with respect to the screen-space y-coordinate.	21
ddy_coarse	Computes a low precision partial derivative with respect to the screen-space y-coordinate.	5
ddy_fine	Computes a high precision partial derivative with respect to the screen-space y-coordinate.	5
degrees	Converts x from radians to degrees.	11
determinant	Returns the determinant of the square matrix m.	11
DeviceMemoryBarrier	Blocks execution of all threads in a group until all device memory accesses have been completed.	5
DeviceMemoryBarrierWithGroupSync	Blocks execution of all threads in a group until all device memory accesses have been completed and all threads in the group have reached this call.	5
distance	Returns the distance between two points.	11
dot	Returns the dot product of two vectors.	1
dst	Calculates a distance vector.	5
EvaluateAttributeAtCentroid	Evaluates at the pixel centroid.	5
EvaluateAttributeAtSample	Evaluates at the indexed sample location.	5
EvaluateAttributeSnapped	Evaluates at the pixel centroid with an offset.	5
exp	Returns the base-e exponent.	11
exp2	Base 2 exponent (per component).	11
f16tof32	Converts the float16 stored in the low-half of the uint to a float.	5
f32tof16	Converts an input into a float16 type.	5
faceforward	Returns -n * sign(dot(i, ng)).	11
firstbithigh	Gets the location of the first set bit starting from the highest order bit and working downward, per component.	5
firstbitlow	Returns the location of the first set bit starting from the lowest order bit and working upward, per component.	5
floor	Returns the greatest integer which is less than or equal to x.	11
fmod	Returns the floating point remainder of x/y.	11
frac	Returns the fractional part of x.	11
frexp	Returns the mantissa and exponent of x.	21
fwidth	Returns abs(ddx(x)) + abs(ddy(x))	21
GetRenderTargetSampleCount	Returns the number of render-target samples.	4
GetRenderTargetSamplePosition	Returns a sample position (x,y) for a given sample index.	4
GroupMemoryBarrier	Blocks execution of all threads in a group until all group shared accesses have been completed.	5
GroupMemoryBarrierWithGroupSync	Blocks execution of all threads in a group until all group shared accesses have been completed and all threads in the group have reached this call.	5
InterlockedAdd	Performs a guaranteed atomic add of value to the dest resource variable.	5
InterlockedAnd	Performs a guaranteed atomic and.	5
InterlockedCompareExchange	Atomically compares the input to the comparison value and exchanges the result.	5
InterlockedCompareStore	Atomically compares the input to the comparison value.	5
InterlockedExchange	Assigns value to dest and returns the original value.	5
InterlockedMax	Performs a guaranteed atomic max.	5
InterlockedMin	Performs a guaranteed atomic min.	5
InterlockedOr	Performs a guaranteed atomic or.	5
InterlockedXor	Performs a guaranteed atomic xor.	5
isfinite	Returns true if x is finite, false otherwise.	11
isinf	Returns true if x is +INF or -INF, false otherwise.	11
isnan	Returns true if x is NAN or QNAN, false otherwise.	11
ldexp	Returns x * 2exp	11
length	Returns the length of the vector v.	11
lerp	Returns x + s(y - x).	11
lit	Returns a lighting vector (ambient, diffuse, specular, 1)	11
log	Returns the base-e logarithm of x.	11
log10	Returns the base-10 logarithm of x.	11
log2	Returns the base-2 logarithm of x.	11
mad	Performs an arithmetic multiply/add operation on three values.	5
max	Selects the greater of x and y.	11
min	Selects the lesser of x and y.	11
modf	Splits the value x into fractional and integer parts.	11
mul	Performs matrix multiplication using x and y.	1
noise	Generates a random value using the Perlin-noise algorithm.	11
normalize	Returns a normalized vector.	11
pow	Returns xy.	11
Process2DQuadTessFactorsAvg	Generates the corrected tessellation factors for a quad patch.	5
Process2DQuadTessFactorsMax	Generates the corrected tessellation factors for a quad patch.	5
Process2DQuadTessFactorsMin	Generates the corrected tessellation factors for a quad patch.	5
ProcessIsolineTessFactors	Generates the rounded tessellation factors for an isoline.	5
ProcessQuadTessFactorsAvg	Generates the corrected tessellation factors for a quad patch.	5
ProcessQuadTessFactorsMax	Generates the corrected tessellation factors for a quad patch.	5
ProcessQuadTessFactorsMin	Generates the corrected tessellation factors for a quad patch.	5
ProcessTriTessFactorsAvg	Generates the corrected tessellation factors for a tri patch.	5
ProcessTriTessFactorsMax	Generates the corrected tessellation factors for a tri patch.	5
ProcessTriTessFactorsMin	Generates the corrected tessellation factors for a tri patch.	5
radians	Converts x from degrees to radians.	1
rcp	Calculates a fast, approximate, per-component reciprocal.	5
reflect	Returns a reflection vector.	1
refract	Returns the refraction vector.	11
reversebits	Reverses the order of the bits, per component.	5
round	Rounds x to the nearest integer	11
rsqrt	Returns 1 / sqrt(x)	11
saturate	Clamps x to the range [0, 1]	1
sign	Computes the sign of x.	11
sin	Returns the sine of x	11
sincos	Returns the sine and cosine of x.	11
sinh	Returns the hyperbolic sine of x	11
smoothstep	Returns a smooth Hermite interpolation between 0 and 1.	11
sqrt	Square root (per component)	11
step	Returns (x >= a) ? 1 : 0	11
tan	Returns the tangent of x	11
tanh	Returns the hyperbolic tangent of x	11
tex1D(s, t)	1D texture lookup.	1
tex1D(s, t, ddx, ddy)	1D texture lookup.	21
tex1Dbias	1D texture lookup with bias.	21
tex1Dgrad	1D texture lookup with a gradient.	21
tex1Dlod	1D texture lookup with LOD.	31
tex1Dproj	1D texture lookup with projective divide.	21
tex2D(s, t)	2D texture lookup.	11
tex2D(s, t, ddx, ddy)	2D texture lookup.	21
tex2Dbias	2D texture lookup with bias.	21
tex2Dgrad	2D texture lookup with a gradient.	21
tex2Dlod	2D texture lookup with LOD.	3
tex2Dproj	2D texture lookup with projective divide.	21
tex3D(s, t)	3D texture lookup.	11
tex3D(s, t, ddx, ddy)	3D texture lookup.	21
tex3Dbias	3D texture lookup with bias.	21
tex3Dgrad	3D texture lookup with a gradient.	21
tex3Dlod	3D texture lookup with LOD.	31
tex3Dproj	3D texture lookup with projective divide.	21
texCUBE(s, t)	Cube texture lookup.	11
texCUBE(s, t, ddx, ddy)	Cube texture lookup.	21
texCUBEbias	Cube texture lookup with bias.	21

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