多光源光照示例程序
在示例程序MultiLights中一共使用了三個光源，分別是漫反射方向光光源、漫反射點光源、鏡面反射方向光光源，而且可以控制分別使用三個光源和同時使用三個光源的顯示效果。為了測試不同光源的光照效果，在示例程序中通過鍵盤上的數字鍵來控制3個光源的啟用。
按下數字鍵1，開啟1號光源，關閉2號和3號光源，從而可以觀察方向光漫反射效果。
按下數字鍵2，開啟2號光源，關閉1號和3號光源，從而可以觀察點光源漫反射效果。
按下數字鍵3，開啟3號光源，關閉1號和1號光源，從而可以觀察方向光鏡面反射效果。
按下數字鍵4，同時開啟3個光源，可以觀察同時使用多個光源的效果。
按下數字鍵0，返回默認狀態，只啟用環境光，關閉所有光源。
按下數字鍵5，啟用FLAT著色模式。
按下數字鍵6，啟用GOURAUD著色模式（默認著色模式)。
源程序：
#include <d3dx9.h>
#pragma warning(disable : 4127)
#define CLASS_NAME "GameApp"
#define release_com(p) do { if(p) { (p)->Release(); (p) = NULL; } } while(0)
IDirect3D9* g_d3d;
IDirect3DDevice9* g_device;
IDirect3DVertexBuffer9* g_vertex_buffer;
struct sCustomVertex
{
D3DXVECTOR3 position;
D3DXVECTOR3 normal;
};
#define D3DFVF_CUSTOM_VERTEX (D3DFVF_XYZ | D3DFVF_NORMAL)
void init_geometry()
{
g_device->CreateVertexBuffer(50 * 2 * sizeof(sCustomVertex), 0, D3DFVF_CUSTOM_VERTEX, D3DPOOL_DEFAULT,
&g_vertex_buffer, NULL);
sCustomVertex* vertices;
g_vertex_buffer->Lock(0, 0, (void**)&vertices, 0);
for(int i = 0; i < 50; i++)
{
float theta = (2 * D3DX_PI * i) / (50 - 1);
vertices[2 * i + 0].position = D3DXVECTOR3(sin(theta), -1.0f, cos(theta));
vertices[2 * i + 0].normal = D3DXVECTOR3(sin(theta), 0.0f, cos(theta));
vertices[2 * i + 1].position = D3DXVECTOR3(sin(theta), 1.0f, cos(theta));
vertices[2 * i + 1].normal = D3DXVECTOR3(sin(theta), 0.0f, cos(theta));
}
g_vertex_buffer->Unlock();
}
void setup_matrices()
{
// build world matrix
D3DXMATRIX mat_world;
D3DXMatrixIdentity(&mat_world);
g_device->SetTransform(D3DTS_WORLD, &mat_world);
// setup view matrix
D3DXVECTOR3 eye(0.0f, 3.0f, -5.0f);
D3DXVECTOR3 at(0.0f, 0.0f, 0.0f);
D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);
D3DXMATRIX mat_view;
D3DXMatrixLookAtLH(&mat_view, &eye, &at, &up);
g_device->SetTransform(D3DTS_VIEW, &mat_view);
// setup projection matrix
D3DXMATRIX mat_proj;
D3DXMatrixPerspectiveFovLH(&mat_proj, D3DX_PI/4, 1.33f, 1.0f, 100.0f);
g_device->SetTransform(D3DTS_PROJECTION, &mat_proj);
}
bool init_d3d(HWND hwnd)
{
g_d3d = Direct3DCreate9(D3D_SDK_VERSION);
if(g_d3d == NULL)
return false;
D3DPRESENT_PARAMETERS d3dpp;
ZeroMemory(&d3dpp, sizeof(d3dpp));
d3dpp.Windowed = TRUE;
d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;
d3dpp.EnableAutoDepthStencil = TRUE; // Direct3D will manage depth buffers for the application
d3dpp.AutoDepthStencilFormat = D3DFMT_D16; // 16-bit z-buffer bit depth
if(FAILED(g_d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hwnd, D3DCREATE_SOFTWARE_VERTEXPROCESSING,
&d3dpp, &g_device)))
{
return false;
}
init_geometry();
setup_matrices();
g_device->SetRenderState(D3DRS_ZENABLE, TRUE);
g_device->SetRenderState(D3DRS_SPECULARENABLE, TRUE);
g_device->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);
return true;
}
void cleanup()
{
release_com(g_vertex_buffer);
release_com(g_device);
release_com(g_d3d);
}
void setup_material_light()
{
// setup material
D3DMATERIAL9 material;
ZeroMemory(&material, sizeof(material));
material.Diffuse.r = material.Ambient.r = material.Specular.r = 0.3f;
material.Diffuse.g = material.Ambient.g = material.Specular.g = 1.0f;
material.Diffuse.b = material.Ambient.b = material.Specular.b = 1.0f;
material.Diffuse.a = material.Ambient.a = material.Specular.a = 1.0f;
g_device->SetMaterial(&material);
// setup light1
D3DLIGHT9 light1;
ZeroMemory(&light1, sizeof(light1));
light1.Type = D3DLIGHT_DIRECTIONAL;
light1.Diffuse.r = 1.0f;
light1.Diffuse.g = 0.8f;
light1.Diffuse.b = 1.0f;
light1.Direction = D3DXVECTOR3(-10, 0, 10);
g_device->SetLight(0, &light1);
// setup light2
D3DLIGHT9 light2;
ZeroMemory(&light2, sizeof(light2));
light2.Type = D3DLIGHT_POINT;
light2.Diffuse.r = 1.0f;
light2.Diffuse.g = 1.0f;
light2.Diffuse.b = 0.0f;
float time = timeGetTime() / 350.0f;
light2.Position = D3DXVECTOR3(10 * sin(time), 0, 10 * cos(time));
light2.Range = 100.0f;
light2.Attenuation0 = 1.0f;
g_device->SetLight(1, &light2);
// setup light3
D3DLIGHT9 light3;
ZeroMemory(&light3, sizeof(light3));
light3.Type = D3DLIGHT_DIRECTIONAL;
light3.Specular.r = 1.0f;
light3.Specular.g = 0.5f;
light3.Specular.b = 0.5f;
light3.Specular.a = 1.0f;
light3.Direction = D3DXVECTOR3(-10, 0, 10);
g_device->SetLight(2, &light3);
g_device->SetRenderState(D3DRS_AMBIENT, 0x00777777);
}
void render()
{
g_device->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(5, 5, 5), 1.0f, 0);
g_device->BeginScene();
setup_material_light();
g_device->SetStreamSource(0, g_vertex_buffer, 0, sizeof(sCustomVertex));
g_device->SetFVF(D3DFVF_CUSTOM_VERTEX);
g_device->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2 * 50 - 2);
g_device->EndScene();
g_device->Present(NULL, NULL, NULL, NULL);
}
LRESULT WINAPI WinProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_KEYDOWN:
switch(wParam)
{
case VK_ESCAPE:
DestroyWindow(hwnd);
return 0;
case 48: // key "0", disalbe all lights, only use ambient light.
g_device->LightEnable(0, FALSE);
g_device->LightEnable(1, FALSE);
g_device->LightEnable(2, FALSE);
break;
case 49: // key "1", enable lights 1, disable other lights.
g_device->LightEnable(0, TRUE);
g_device->LightEnable(1, FALSE);
g_device->LightEnable(2, FALSE);
break;
case 50: // key "2", enable lights 2, disable other lights.
g_device->LightEnable(0, FALSE);
g_device->LightEnable(1, TRUE);
g_device->LightEnable(2, FALSE);
break;
case 51: // key "3", enable lights 3, disable other lights.
g_device->LightEnable(0, FALSE);
g_device->LightEnable(1, FALSE);
g_device->LightEnable(2, TRUE);
break;
case 52: // key "4", enable all lights.
g_device->LightEnable(0, TRUE);
g_device->LightEnable(1, TRUE);
g_device->LightEnable(2, TRUE);
break;
case 53: // key "5", flat shade mode.
g_device->SetRenderState(D3DRS_SHADEMODE, D3DSHADE_FLAT);
break;
case 54: // key "6", gouraud shade mode.
g_device->SetRenderState(D3DRS_SHADEMODE, D3DSHADE_GOURAUD);
break;
}
break;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, msg, wParam, lParam);
}
int WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR, INT)
{
WNDCLASSEX wc;
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_CLASSDC;
wc.lpfnWndProc = WinProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = inst;
wc.hIcon = NULL;
wc.hCursor = NULL;
wc.hbrBackground = NULL;
wc.lpszMenuName = NULL;
wc.lpszClassName = CLASS_NAME;
wc.hIconSm = NULL;
if(! RegisterClassEx(&wc))
return -1;
HWND hwnd = CreateWindow(CLASS_NAME, "Direct3D App", WS_OVERLAPPEDWINDOW, 200, 100, 640, 480,
NULL, NULL, wc.hInstance, NULL);
if(hwnd == NULL)
return -1;
if(init_d3d(hwnd))
{
ShowWindow(hwnd, SW_SHOWDEFAULT);
UpdateWindow(hwnd);
MSG msg;
ZeroMemory(&msg, sizeof(msg));
while(msg.message != WM_QUIT)
{
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
render();
}
}
cleanup();
UnregisterClass(CLASS_NAME, wc.hInstance);
return 0;
}
場景中的環境光有兩個來源：一是通過渲染狀態設置的全局環境光，二是通過每個光源中的環境光屬性設置的環境光。建議通過渲染狀態設置一個整體上的環境光，對于場景中的各個光源不設置其環境光屬性，因為在同一個場景中，對于每個物體其接受到的環境光應當相同，所以通過渲染狀態設置一個整體上的環境光比較方便，也符合實際情況。
在Direct3D中，光源和材質是互不分離、相互作用的兩部分，光源是相對于整個場景的，而材質是相對于每個物體的。兩者相互作用，共同決定最終的渲染結果，這樣雖然靈活但不易控制，所以光源和物體表面材質的設置應盡量符合現實情況。例如，可將光源設為白光，將各個物體材質顏色設為真實顏色，當然為了得到特殊的效果，可以在某些方面進行夸張。