高级着色语言HLSL入门（2

高级着色语言HLSL入门（2
16.2.1 常量表

每个着色器有一个常量表，用来保存它的变量。D3DX库通过ID3DXConstantTable接口，提供给应用程序访问着色器的常量表。通过这个接口我们能够在应用程序中设置着色器源代码中的变量。

我们现在描述ID3DXConstantTable接口的方法列表的实现，全部的列表请查阅Direct3D文档。

16.2.1.1 取得常量句柄

为了在应用程序中设置着色器中的一个特定变量，需要有一种方法去引用它，我们能够在应用程序中用D3DXHANDLE引用一个在着色器中的变量，下面的方法返回一个着色器中的变量的D3DXHANDLE，使用时，需要传递一个变量的名字作为参数：

D3DXHANDLE ID3DXConstantTable::GetConstantByName(

D3DXHANDLE hConstant, // scope of constant

LPCSTR pName // name of constant

);

Hconstant——我们要取得的父结构中变量句柄的D3DXHANDLE标识。例如，如果我们想获得一个特定数据结构中单一数据成员的句柄，我们可以传递结构实例的句柄。如果我们获得一个顶级变量的句柄，给这个参数设为NULL。

PName——我们想获得的句柄的着色器代码中的变量的名字。

Gets a constant by looking up its name.
```
D3DXHANDLE GetConstantByName(
  D3DXHANDLE hConstant,
  LPCSTR pName
);
```
Parameters

hConstant
[in] Unique identifier to the parent data structure. If the constant is a top-level parameter (there is no parent data structure), use NULL.
pName
[in] Name of the constant.

Return Values

Returns a unique identifier to the constant.

例如，如果在着色器中变量的名字为ViewProjMatrix，并且这是顶级变量，我们这么写：

// 取得着色器中ViewProjMatrix变量的句柄

D3DXHANDLE h0;

h0 = ConstTable->GetConstantByName(0, "ViewProjMatrix");

16.2.1.2 设置常量

一旦应用程序有了一个D3DXHANDLE，要引用着色器代码中的具体变量，我们可以在应用程序中使用ID3DXConstantTable::SetXXX方法设置变量。如果我们想设置一个向量数组类型的变量，方法名是SetVectorArray。

ID3DXConstantTable::SetXXX的一般语法是：

HRESULT ID3DXConstantTable::SetXXX(

     LPDIRECT3DDEVICE9 pDevice,

     D3DXHANDLE hConstant,

     XXX value

);

PDevice：常量表所关联的设备的指针。

HConstant：我们正在设置的变量句柄的引用。

Value：我们要把变量设置成的值，XXX是我们设置的要替换的变量类型名，对于有些类型（bool, int, float），传递变量值的COPY，另外一些类型（vectors, matrices, structures），传递值的指针。

下面的列表描述了我们能用ID3DXConstantTable接口设置的类型列表。这里假定我们有一个有效的设备，和一个有效句柄。

SetBool—Used to set a Boolean value. Sample call:
bool b = true;

ConstTable->SetBool(Device, handle, b);
Sets a Boolean value.
```
HRESULT SetBool(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  BOOL b
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the constant. See D3DXHANDLE.
b
[in] Boolean value.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetBoolArray—Used to set a Boolean array. Sample call:
bool b[3] = {true, false, true};

ConstTable->SetBoolArray(Device, handle, b, 3);
Sets an array of Boolean values.
```
HRESULT SetBoolArray(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  CONST BOOL* pB,
  UINT Count
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the array of constants. See D3DXHANDLE.
pB
[in] Array of Boolean values.
Count
[in] Number of Boolean values in the array.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetFloat—Used to set a float. Sample call:
float f = 3.14f;

ConstTable->SetFloat(Device, handle, f);
Sets a floating-point number.
```
HRESULT SetFloat(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  FLOAT f
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the constant. See D3DXHANDLE.
f
[in] Floating-point number.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetFloatArray—Used to set a float array. Sample call:

float f[2] = {1.0f, 2.0f};

ConstTable->SetFloatArray(Device, handle, f, 2);

Sets an array of floating-point numbers.
```
HRESULT SetFloatArray(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  CONST FLOAT* pf,
  UINT Count
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the array of constants. See D3DXHANDLE.
pf
[in] Array of floating-point numbers.
Count
[in] Number of floating-point values in the array.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetInt—Used to set an integer. Sample call:

int x = 4;

ConstTable->SetInt(Device, handle, x);

Sets an integer value.
```
HRESULT SetInt(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  INT n
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the constant. See D3DXHANDLE.
n
[in] Integer.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetMatrix—Used to set a 4 × 4 matrix. Sample call:

D3DXMATRIX M(…);

ConstTable->SetMatrix(Device, handle, &M);

Sets a nontransposed matrix.
```
HRESULT SetMatrix(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  CONST D3DXMATRIX* pMatrix
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the matrix of constants. See D3DXHANDLE.
pMatrix
[in] Pointer to a nontransposed matrix. See D3DXMATRIX.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetMatrixArray—Used to set a 4 × 4 matrix array. Sample call:

D3DXMATRIX M[4];

// ...Initialize matrices

ConstTable->SetMatrixArray(Device, handle, M, 4);

Sets an array of nontransposed matrices.
```
HRESULT SetMatrixArray(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  CONST D3DXMATRIX* pMatrix,
  UINT Count
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to the array of constant matrices.
pMatrix
[in] Array of nontransposed matrices.
Count
[in] Number of matrices in the array.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

SetMatrixPointerArray—Used to set an array of 4 × 4 matrix pointers. Sample call:

D3DXMATRIX* M[4];

// ...Allocate and initialize matrix pointers

ConstTable->SetMatrixPointerArray(Device, handle, M, 4);

Sets an array of pointers to nontransposed matrices.
```
HRESULT SetMatrixPointerArray(
  LPDIRECT3DDEVICE9 pDevice,
  D3DXHANDLE hConstant,
  CONST D3DXMATRIX ** ppMatrix,
  UINT Count
);
```
Parameters

pDevice
[in] Pointer to an IDirect3DDevice9 interface, representing the device associated with the constant table.
hConstant
[in] Unique identifier to an array of constant matrices.
ppMatrix
[in] Array of pointers to nontransposed matrices.
Count
[in] Number of matrices in the array.

Return Values

If the method succeeds, the return value is D3D_OK. If the method fails, the return value can be D3DERR_INVALIDCALL.

Remarks

A nontransposed matrix contains row-major data; that is, each vector is contained in a row.
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原文地址：https://www.cnblogs.com/8586/p/1401970.html

高级着色语言HLSL入门（2

16.2.1 常量表

16.2.1.1 取得常量句柄

Parameters

Return Values

16.2.1.2 设置常量

Parameters

Return Values

Parameters

Return Values

Parameters

Return Values

Parameters

Return Values

Parameters

Return Values

Parameters

Return Values

Parameters

Return Values

Parameters

Return Values

Remarks