CG中的类型

【Matrix】

　　通常像下面这样定义Matrix：

int1x1    iMatrix;   // integer matrix with 1 row,  1 column
int4x1    iMatrix;   // integer matrix with 4 rows, 1 column
int1x4    iMatrix;   // integer matrix with 1 row, 4 columns
double3x3 dMatrix;   // double matrix with 3 rows, 3 columns

float2x2 fMatrix = { 0.0f, 0.1, // row 1
                     2.1f, 2.2f // row 2
                   };   

　　也可以像下面这样定义Matrix:

matrix <Type, Number> VariableName
matrix <float, 2, 2> fMatrix = { 0.0f, 0.1, // row 1
                                 2.1f, 2.2f // row 2
                               };

　　Member access for matrix types

_m00, _m01,_m02, _m03 

_m10, _m11,_m12, _m13 

_m20, _m21,_m22, _m23 

_m30, _m31,_m32, _m33 

or

_11, _12,_13, _14 

_21, _22,_23, _24 

_31, _32,_33, _34 

_41, _42,_43, _4

参考：http://msdn.microsoft.com/en-us/library/windows/desktop/bb509623(v=vs.85).aspx

【Vector】

　　通常像下面这样定义Vector：

bool    bVector;   // scalar containing 1 Boolean
int1    iVector = 1;
float3  fVector = { 0.2f, 0.3f, 0.4f };

　　也可像下面这样定义：

vector <Type, Number> VariableName

vector <int,    1> iVector = 1;
vector <double, 4> dVector = { 0.2, 0.3, 0.4, 0.5 };

【Scalar】

• bool - true or false.
• int - 32-bit signed integer.
• uint - 32-bit unsigned integer.
• dword - 32-bit unsigned integer.
• half - 16-bit floating point value. This data type is provided only for language compatibility. Direct3D 10 shader targets map all half data types to float data types. A half data type cannot be used on a uniform global variable (use the /Gec flag if this functionality is desired).
• float - 32-bit floating point value.
• double - 64-bit floating point value. You cannot use double precision values as inputs and outputs for a stream. To pass double precision values between shaders, declare each double as a pair of uint data types. Then, use the asdouble function to pack each double into the pair of uints and the asuint function to unpack the pair of uints back into the double.

【Per-Component Math Operations】

　　可以单独取出Vector中的分量进行计算：

float4 pos = float4(0,0,2,1);
float2 f_2D;
f_2D = pos.xy;   // read two components 
f_2D = pos.xz;   // read components in any order       
f_2D = pos.zx;

f_2D = pos.xx;   // components can be read more than once
f_2D = pos.yy;

　　读取matrix的某一行：

float2 temp;
float2x2 fMatrix;
temp = fMatrix[0] // read the first row

参考：http://msdn.microsoft.com/en-us/library/windows/desktop/bb509634(v=vs.85).aspx