17. 增加对硬件光照的支持

该游戏项目一开始先创建名为light.h、material.h的两个文件。

light.h头文件用于创建灯源结构，该结构用于创建Direct3D中的灯源对象。以某种方式实现该结构，这样也可将其用于OpenGL或其他渲染系统。光源结构模仿了Direct3D中的D3DLIGHT结构，所以它们是完全兼容的。

light.h

#ifndef _UGP_LIGHT_H_
#define _UGP_LIGHT_H_

struct stLight
{
   stLight()
   {
      type = 0;
      posX = 0, posY = 0, posZ = 0;
      dirX = 0, dirY = 0, dirZ = 0;
      ambientR = ambientG = ambientB = ambientA = 1;
      diffuseR = diffuseG = diffuseB = diffuseA = 1;
      specularR = specularG = specularB = specularA = 0;
      range = 0;
      falloff = 0;
      attenuation0 = 0;
      attenuation1 = 0;
      attenuation2 = 0;
      theta = 0;
      phi = 0;
   }

   int type;
   float posX, posY, posZ;
   float dirX, dirY, dirZ;
   float ambientR, ambientG, ambientB, ambientA;
   float diffuseR, diffuseG, diffuseB, diffuseA;
   float specularR, specularG, specularB, specularA;
   float range;
   float falloff;
   float attenuation0;
   float attenuation1;
   float attenuation2;
   float theta;
   float phi;
};

#endif

　　material.h

// ========================================================================
//§ material.h 文件
//§ 
//§ 【描述】：定义材质结构：stMaterial
//§
// ========================================================================

#ifndef _UGP_MATERIAL_H_
#define _UGP_MATERIAL_H_

struct stMaterial
{
   stMaterial()
   {
      emissiveR = emissiveG = emissiveB = emissiveA = 0;
      ambientR = ambientG = ambientB = ambientA = 1;
      diffuseR = diffuseG = diffuseB = diffuseA = 1;
      specularR = specularG = specularB = specularA = 0;
      power = 0;
   }

   float emissiveR, emissiveG, emissiveB, emissiveA;
   float ambientR, ambientG, ambientB, ambientA;
   float diffuseR, diffuseG, diffuseB, diffuseA;
   float specularR, specularG, specularB, specularA;
   float power;
};

#endif
    

　　

    Direct3D渲染系统需要一种创建光源和材质的方法。这可以通过为渲染系统添加三个新函数来实现。第一个函数是SetMaterial()，它的参数包括材质(stMaterial)对象，并将其施加到渲染设备上。第二个新函数是SetLight()，它的参数包括灯源对象、灯源索引(因为Direct3D和OpenGL由多达8个的硬件光源，所以索引值可以是0~7)，并且调用必须的Direct3D函数用于在硬件中创建和注册光源。最后一个新函数是DisalbeLight()，它以想要关闭灯源的索引为参数。给出了新增加的CD3DRenderer和CRenderInterface类。

class CRenderInterface
{
    // ...The beginning of the class functions...
    
    // 设置材质
    virtual void SetMaterial(stMaterial *mat) = 0;

    // 设置并启用光源
    virtual void SetLight(stLight *light, int index) = 0;

    // 关闭光源
    virtual void DisableLight(int index) = 0;
    
    // ...The rest of the class's functions...
};


class CD3DRenderer : public CRenderInterface
{
    // ...The beginning of the class functions...
    
    // 设置材质
    void SetMaterial(stMaterial *mat);

    // 设置并启用光源
    void SetLight(stLight *light, int index);
      
    // 关闭光源
    void DisableLight(int index);
    
    // ...The rest of the class's functions...
};
    

　　D3DRenderer.cpp源文件实现了三个和Direct3D打交道的函数。SetMaterial()函数使用材质结构中的信息创建Direct3D材质对象，并调用Direct3D设备函数SetMaterial()将该对象直接发送给Direct3D。这同样使用于SetLight()函数。SetLight()函数的参数包括光源结构，该函数使用该参数设置D3DLIGHT9对象，并将其直接发送给Direct3D。DisableLight()函数的参数包括光源索引，它将关闭注册在该索引上的所有光源。给出了这些函数的源代码。

// 设置材质
void CD3DRenderer::SetMaterial(stMaterial *mat)
{
   if(!mat || !m_Device) return;

   D3DMATERIAL9 m = { mat->diffuseR, mat->diffuseG,
                     mat->diffuseB, mat->diffuseA,
                     mat->ambientR, mat->ambientG,
                     mat->ambientB, mat->ambientA,
                     mat->specularR, mat->specularG,
                     mat->specularB, mat->specularA,
                     mat->emissiveR, mat->emissiveG,
                     mat->emissiveB, mat->emissiveA,
                     mat->power
   };

   m_Device->SetMaterial(&m);
}



// 设置并启用光源
void CD3DRenderer::SetLight(stLight *light, int index)
{
   if(!light || !m_Device || index < 0) return;

   D3DLIGHT9 l;

   l.Ambient.a = light->ambientA;
   l.Ambient.r = light->ambientR;
   l.Ambient.g = light->ambientG;
   l.Ambient.b = light->ambientB;
   l.Attenuation0 = light->attenuation0;
   l.Attenuation1 = light->attenuation1;
   l.Attenuation2 = light->attenuation2;
   l.Diffuse.a = light->diffuseA;
   l.Diffuse.r = light->diffuseR;
   l.Diffuse.g = light->diffuseG;
   l.Diffuse.b = light->diffuseB;
   l.Direction.x = light->dirX;
   l.Direction.y = light->dirY;
   l.Direction.z = light->dirZ;
   l.Falloff = light->falloff;
   l.Phi = light->phi;
   l.Position.x = light->posX;
   l.Position.y = light->posY;
   l.Position.z = light->posZ;
   l.Range = light->range;
   l.Specular.a = light->specularA;
   l.Specular.r = light->specularR;
   l.Specular.g = light->specularG;
   l.Specular.b = light->specularB;
   l.Theta = light->theta;


   if(light->type == LIGHT_POINT) l.Type = D3DLIGHT_POINT;
   else if (light->type == LIGHT_SPOT) l.Type = D3DLIGHT_SPOT;
   else l.Type = D3DLIGHT_DIRECTIONAL;

   m_Device->SetLight(index, &l);
   m_Device->LightEnable(index, TRUE);
}


// 关闭光源
void CD3DRenderer::DisableLight(int index)
{
   if(!m_Device) return;

   m_Device->LightEnable(index, FALSE);
}
    

　　

还需要在“defines.h”头文件里加入这几行代码：

// Light type defines. 
// 光源类型
#define LIGHT_POINT 1 　　　　　// 点光源
#define LIGHT_DIRECTIONAL 2 　// 方向光
#define LIGHT_SPOT 3　　　　　 // 聚光灯