An Introduction to Lighting in Direct3D

An Introduction to Lighting in Direct3D
with Examples in C++

Prof. David Bernstein
James Madison University

Computer Science Department

bernstdh@jmu.edu

Parts of the Process

Specify normal vectors
Specify material properties
Create and position light sources
Specify properties of the lighting model
Enable lighting and light sources

Specifying Normal Vectors

The Custom Vertex struct:

Can use a D3DXVECTOR3


                           struct CUSTOMVERTEX
{
    D3DXVECTOR3 position;
    D3DXVECTOR3 normal;
};

Set the Flexible Vertex Format (FVF):
- Use the bitflag D3DFVF_NORMAL

Specifying Normal Vectors (cont.)

An Example

directx9examples/lighting/cube/cube.cpp

(Fragment: vertices)

        // Specify the struct for a vertex
struct CUSTOMVERTEX
{
    float x, y, z;
        float nx, ny, nz;
};

// Specify the flexible vertex format (FVF) for the struct above
#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ | D3DFVF_NORMAL)


// Color Definitions
DWORD colorBlue   = 0xFF0000FF;
DWORD colorGold   = 0xFFC2A14D; // JMU Gold
DWORD colorGray   = 0xFFAAAAAA;
DWORD colorGreen  = 0xFF00FF00;
DWORD colorPurple = 0xFF450084; // JMU Purple
DWORD colorRed    = 0xFFFF0000;
DWORD colorYellow = 0xFFFFFF00;

// Create the vertex elements
CUSTOMVERTEX vertices[] =
{
        {-1.0f, 1.0f,-1.0f,  0.0f,  0.0f, -1.0f}, // Front
        { 1.0f, 1.0f,-1.0f,  0.0f,  0.0f, -1.0f},
        {-1.0f,-1.0f,-1.0f,  0.0f,  0.0f, -1.0f},
        { 1.0f,-1.0f,-1.0f,  0.0f,  0.0f, -1.0f},
        
        {-1.0f, 1.0f, 1.0f,  0.0f,  0.0f,  1.0f}, // Back
        {-1.0f,-1.0f, 1.0f,  0.0f,  0.0f,  1.0f},
        { 1.0f, 1.0f, 1.0f,  0.0f,  0.0f,  1.0f},
        { 1.0f,-1.0f, 1.0f,  0.0f,  0.0f,  1.0f},
        
        {-1.0f, 1.0f, 1.0f,  0.0f,  1.0f,  0.0f}, // Top
        { 1.0f, 1.0f, 1.0f,  0.0f,  1.0f,  0.0f},
        {-1.0f, 1.0f,-1.0f,  0.0f,  1.0f,  0.0f},
        { 1.0f, 1.0f,-1.0f,  0.0f,  1.0f,  0.0f},
        
        {-1.0f,-1.0f, 1.0f,  0.0f, -1.0f,  0.0f}, // Bottom
        {-1.0f,-1.0f,-1.0f,  0.0f, -1.0f,  0.0f},
        { 1.0f,-1.0f, 1.0f,  0.0f, -1.0f,  0.0f},
        { 1.0f,-1.0f,-1.0f,  0.0f, -1.0f,  0.0f},

        { 1.0f, 1.0f,-1.0f,  1.0f,  0.0f,  0.0f}, // Right
        { 1.0f, 1.0f, 1.0f,  1.0f,  0.0f,  0.0f},
        { 1.0f,-1.0f,-1.0f,  1.0f,  0.0f,  0.0f},
        { 1.0f,-1.0f, 1.0f,  1.0f,  0.0f,  0.0f},
        
        {-1.0f, 1.0f,-1.0f, -1.0f,  0.0f,  0.0f}, // Left
        {-1.0f,-1.0f,-1.0f, -1.0f,  0.0f,  0.0f},
        {-1.0f, 1.0f, 1.0f, -1.0f,  0.0f,  0.0f},
        {-1.0f,-1.0f, 1.0f, -1.0f,  0.0f,  0.0f}
};

Specifying Material Properties

D3DMATERIAL9:


                           typedef struct D3DMATERIAL9 
{
  D3DCOLORVALUE diffuse; 
  D3DCOLORVALUE ambient; 
  D3DCOLORVALUE specular; 
  D3DCOLORVALUE emissive; 
  float         exponent;
}

D3DCOLORVALUE:


                           typedef struct D3DCOLORVALUE 
{
  float r; 
  float g; 
  float b; 
  float alpha;
}

Specifying Material Properties (cont.)

An Example

directx9examples/lighting/cube/cube.cpp

(Fragment: material)

                // Specify the properties for brass
    D3DMATERIAL9 brass = {
                      {0.78f, 0.57f, 0.11f, 1.00f}, // Diffuse RGBA
                      {0.33f, 0.22f, 0.03f, 1.00f}, // Ambient RGBA
                      {0.99f, 0.94f, 0.81f, 1.00f}, // Specular RGBA
                      {0.00f, 0.00f, 0.00f, 1.00f}, // Emissive RGBA
                      27.89f
                     };
                                         
        // Tell the device to make brasas the current material
        d3dDevice->SetMaterial(&brass);

Creating and Positioning Light Sources

D3DLIGHT9:


                           typedef struct D3DLIGHT9 
{
  D3DLIGHTTYPE  type;
  D3DCOLORVALUE diffuse;
  D3DCOLORVALUE specular;
  D3DCOLORVALUE ambient;
  D3DVECTOR     position;
  D3DVECTOR     direction;
  float         range;
  float         falloff;
  float         attenuation0;
  float         attenuation1;
  float         attenuation2;
  float         theta;
  float         phi;
}

Type of Light:
- Point
- Directional
- Spotlight

Light Sources (cont.)

An Example

directx9examples/lighting/cube/cube.cpp

(Fragment: lightsource)

                // Declare a light source
        D3DLIGHT9   light;

        // Clear the memory since we aren't setting all components
        ZeroMemory( &light, sizeof(light) );

        // Initialize the light source
        light.Type      = D3DLIGHT_DIRECTIONAL;
        light.Diffuse.r = 1.0f;
        light.Diffuse.g = 1.0f;
        light.Diffuse.b = 1.0f;
        light.Range     = 1.0f;

        // Declare a direction vector
        D3DXVECTOR3 direction;

        // Change the direction over time
        direction = D3DXVECTOR3(cosf(timeGetTime()/360.0f),
                                    0.0f,
                                        sinf(timeGetTime()/360.0f));

        // Normalize the direction vector
        D3DXVec3Normalize((D3DXVECTOR3*)&light.Direction, &direction);

        // Tell the device to use the light source
        d3dDevice->SetLight(0, &light);

Specifying the Lighting Model

The Function:
- HRESULT IDirect3DDevice9::SetRenderState(D3DRENDERSTATETYPE name, DWORD value);
An Important Name-Value Pair:
- Name: D3DRS_AMBIENT
- Value: A color

Enabling Lighting

The Method:
- HRESULT IDirect3DDevice9::SetRenderState(D3DRENDERSTATETYPE type, DWORD value)
The Name-Value Pair:
- type is D3DRS_LIGHTING and the value is TRUE

Light Sources (cont.)

An Example of Setting-Up Lighting

directx9examples/lighting/cube/cube.cpp

(Fragment: setupLighting)

                // Set the lighting properties
        d3dDevice->SetRenderState(D3DRS_LIGHTING, TRUE);
        d3dDevice->SetRenderState(D3DRS_AMBIENT, 0x00AAAAAA);

Enabling Lights

The Method:
- HRESULT IDirect3DDevice9::LightEnable(DWORD index, BOOL enable)
The Parameters:
- index is the ID of the light
- enable is TRUE or FALSE

Light Sources (cont.)

An Example of Enabling a Light

directx9examples/lighting/cube/cube.cpp

(Fragment: enable)

                // Enable lighhting
        d3dDevice->LightEnable(0, TRUE);