Tutorial 9: Ambient Lighting

This tutorial will be an introduction to using ambient lighting in DirectX 10 with HLSL.

I will explain ambient lighting using an example. Imagine you are in a room and the only light source is sunlight which is coming in from a window. The sunlight doesn't directly point at all the surfaces in the room but everything in the room is illuminated to a certain extent due to bouncing light particles. This lighting effect on the surfaces that the sun isn't directly pointing at is called ambient lighting.

Now to simulate ambient lighting we use a very simple equation. We just set each pixel to be the value of the ambient light at the start of the pixel shader. From that point forward all other operations just add their value to the ambient color. This way we ensure everything is at a minimum using the ambient color value.

Ambient lighting also adds far more realism to a 3D scene. Take for example the following picture that has only diffuse lighting pointing down the positive X axis at a cube:

The image produced doesn't look realistic because ambient light is almost always everywhere giving everything their proper shape even if it is only slightly illuminated. Now if we just add 15% ambient white light to the same scene we get the following image instead:

This now gives us a more realistic lighting effect that we as humans are used to.

We will now look at the changes to the code to implement ambient lighting. This tutorial is built on the previous tutorials that used diffuse lighting. We will now add the ambient component with just a few changes.


Light.fx

////////////////////////////////////////////////////////////////////////////////
// Filename: light.fx
////////////////////////////////////////////////////////////////////////////////


/////////////
// GLOBALS //
/////////////
matrix worldMatrix;
matrix viewMatrix;
matrix projectionMatrix;
Texture2D shaderTexture;

First we add a 4 float ambient color value so that the ambient color can be set in this shader by outside classes.

float4 ambientColor;
float4 diffuseColor;
float3 lightDirection;


///////////////////
// SAMPLE STATES //
///////////////////
SamplerState SampleType
{
    Filter = MIN_MAG_MIP_LINEAR;
    AddressU = Wrap;
    AddressV = Wrap;
};


//////////////
// TYPEDEFS //
//////////////
struct VertexInputType
{
    float4 position : POSITION;
    float2 tex : TEXCOORD0;
    float3 normal : NORMAL;
};

struct PixelInputType
{
    float4 position : SV_POSITION;
    float2 tex : TEXCOORD0;
    float3 normal : NORMAL;
};


////////////////////////////////////////////////////////////////////////////////
// Vertex Shader
////////////////////////////////////////////////////////////////////////////////
PixelInputType LightVertexShader(VertexInputType input)
{
    PixelInputType output;
    
    
    // Change the position vector to be 4 units for proper matrix calculations.
    input.position.w = 1.0f;

    // Calculate the position of the vertex against the world, view, and projection matrices.
    output.position = mul(input.position, worldMatrix);
    output.position = mul(output.position, viewMatrix);
    output.position = mul(output.position, projectionMatrix);
    
    // Store the texture coordinates for the pixel shader.
    output.tex = input.tex;
    
    // Calculate the normal vector against the world matrix only.
    output.normal = mul(input.normal, (float3x3)worldMatrix);
	
    // Normalize the normal vector.
    output.normal = normalize(output.normal);

    return output;
}


////////////////////////////////////////////////////////////////////////////////
// Pixel Shader
////////////////////////////////////////////////////////////////////////////////
float4 LightPixelShader(PixelInputType input) : SV_Target
{
    float4 textureColor;
    float3 lightDir;
    float lightIntensity;
    float4 color;


    // Sample the pixel color from the texture using the sampler at this texture coordinate location.
    textureColor = shaderTexture.Sample(SampleType, input.tex);

We set the output color value to the base ambient color. All pixels will now be illuminated by a minimum of the ambient color value.

    // Set the default output color to the ambient light value for all pixels.
    color = ambientColor;

    // Invert the light direction for calculations.
    lightDir = -lightDirection;

    // Calculate the amount of light on this pixel.
    lightIntensity = saturate(dot(input.normal, lightDir));

Check if the N dot L is greater than zero. If it is then add the diffuse color to the ambient color. If not then you need to be careful to not add the diffuse color. The reason being is that the diffuse color could be negative and it will subtract away some of the ambient color in the addition which is not correct.

    if(lightIntensity > 0.0f)
    {
        // Determine the final diffuse color based on the diffuse color and the amount of light intensity.
        color += (diffuseColor * lightIntensity);
    }

Make sure to saturate the final output light color since the combination of ambient and diffuse could have been greater than 1.

    // Saturate the final light color.
    color = saturate(color);

    // Multiply the texture pixel and the final diffuse color to get the final pixel color result.
    color = color * textureColor;

    return color;
}


////////////////////////////////////////////////////////////////////////////////
// Technique
////////////////////////////////////////////////////////////////////////////////
technique10 LightTechnique
{
    pass pass0
    {
        SetVertexShader(CompileShader(vs_4_0, LightVertexShader()));
        SetPixelShader(CompileShader(ps_4_0, LightPixelShader()));
        SetGeometryShader(NULL);
    }
}

Lightshaderclass.h

////////////////////////////////////////////////////////////////////////////////
// Filename: lightshaderclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _LIGHTSHADERCLASS_H_
#define _LIGHTSHADERCLASS_H_


//////////////
// INCLUDES //
//////////////
#include <d3d10.h>
#include <d3dx10math.h>
#include <fstream>
using namespace std;


////////////////////////////////////////////////////////////////////////////////
// Class name: LightShaderClass
////////////////////////////////////////////////////////////////////////////////
class LightShaderClass
{
public:
	LightShaderClass();
	LightShaderClass(const LightShaderClass&);
	~LightShaderClass();

	bool Initialize(ID3D10Device*, HWND);
	void Shutdown();
	void Render(ID3D10Device*, int, D3DXMATRIX, D3DXMATRIX, D3DXMATRIX, ID3D10ShaderResourceView*, D3DXVECTOR3, D3DXVECTOR4, D3DXVECTOR4);

private:
	bool InitializeShader(ID3D10Device*, HWND, WCHAR*);
	void ShutdownShader();
	void OutputShaderErrorMessage(ID3D10Blob*, HWND, WCHAR*);

	void SetShaderParameters(D3DXMATRIX, D3DXMATRIX, D3DXMATRIX, ID3D10ShaderResourceView*, D3DXVECTOR3, D3DXVECTOR4, D3DXVECTOR4);
	void RenderShader(ID3D10Device*, int);

private:
	ID3D10Effect* m_effect;
	ID3D10EffectTechnique* m_technique;
	ID3D10InputLayout* m_layout;

	ID3D10EffectMatrixVariable* m_worldMatrixPtr;
	ID3D10EffectMatrixVariable* m_viewMatrixPtr;
	ID3D10EffectMatrixVariable* m_projectionMatrixPtr;
	ID3D10EffectShaderResourceVariable* m_texturePtr;
	ID3D10EffectVectorVariable* m_lightDirectionPtr;

The LightShaderClass now has a new private pointer to the ambient color.

	ID3D10EffectVectorVariable* m_ambientColorPtr;
	ID3D10EffectVectorVariable* m_diffuseColorPtr;
};

#endif

Lightshaderclass.cpp

////////////////////////////////////////////////////////////////////////////////
// Filename: lightshaderclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "lightshaderclass.h"


LightShaderClass::LightShaderClass()
{
	m_effect = 0;
	m_technique = 0;
	m_layout = 0;

	m_worldMatrixPtr = 0;
	m_viewMatrixPtr = 0;
	m_projectionMatrixPtr = 0;
	m_texturePtr = 0;
	m_lightDirectionPtr = 0;

Initialize the ambient light pointer to null in the class constructor.

	m_ambientColorPtr = 0;
	m_diffuseColorPtr = 0;
}


LightShaderClass::LightShaderClass(const LightShaderClass& other)
{
}


LightShaderClass::~LightShaderClass()
{
}


bool LightShaderClass::Initialize(ID3D10Device* device, HWND hwnd)
{
	bool result;


	// Initialize the shader that will be used to draw the triangle.
	result = InitializeShader(device, hwnd, L"../Engine/light.fx");
	if(!result)
	{
		return false;
	}

	return true;
}


void LightShaderClass::Shutdown()
{
	// Shutdown the shader effect.
	ShutdownShader();

	return;
}

The Render function now takes in an ambient color value which it then sets in the shader before rendering.

void LightShaderClass::Render(ID3D10Device* device, int indexCount, D3DXMATRIX worldMatrix, D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix, 
			      ID3D10ShaderResourceView* texture, D3DXVECTOR3 lightDirection, D3DXVECTOR4 ambientColor, D3DXVECTOR4 diffuseColor)
{
	// Set the shader parameters that it will use for rendering.
	SetShaderParameters(worldMatrix, viewMatrix, projectionMatrix, texture, lightDirection, ambientColor, diffuseColor);

	// Now render the prepared buffers with the shader.
	RenderShader(device, indexCount);

	return;
}


bool LightShaderClass::InitializeShader(ID3D10Device* device, HWND hwnd, WCHAR* filename)
{
	HRESULT result;
	ID3D10Blob* errorMessage;
	D3D10_INPUT_ELEMENT_DESC polygonLayout[3];
	unsigned int numElements;
	D3D10_PASS_DESC passDesc;


	// Initialize the error message.
	errorMessage = 0;

	// Load the shader in from the file.
	result = D3DX10CreateEffectFromFile(filename, NULL, NULL, "fx_4_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, 
					    device, NULL, NULL, &m_effect, &errorMessage, NULL);
	if(FAILED(result))
	{
		// If the shader failed to compile it should have writen something to the error message.
		if(errorMessage)
		{
			OutputShaderErrorMessage(errorMessage, hwnd, filename);
		}
		// If there was nothing in the error message then it simply could not find the shader file itself.
		else
		{
			MessageBox(hwnd, filename, L"Missing Shader File", MB_OK);
		}

		return false;
	}

	// Get a pointer to the technique inside the shader.
	m_technique = m_effect->GetTechniqueByName("LightTechnique");
	if(!m_technique)
	{
		return false;
	}

	// Now setup the layout of the data that goes into the shader.
	// This setup needs to match the VertexType stucture in the ModelClass and in the shader.
	polygonLayout[0].SemanticName = "POSITION";
	polygonLayout[0].SemanticIndex = 0;
	polygonLayout[0].Format = DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[0].InputSlot = 0;
	polygonLayout[0].AlignedByteOffset = 0;
	polygonLayout[0].InputSlotClass = D3D10_INPUT_PER_VERTEX_DATA;
	polygonLayout[0].InstanceDataStepRate = 0;

	polygonLayout[1].SemanticName = "TEXCOORD";
	polygonLayout[1].SemanticIndex = 0;
	polygonLayout[1].Format = DXGI_FORMAT_R32G32_FLOAT;
	polygonLayout[1].InputSlot = 0;
	polygonLayout[1].AlignedByteOffset = D3D10_APPEND_ALIGNED_ELEMENT;
	polygonLayout[1].InputSlotClass = D3D10_INPUT_PER_VERTEX_DATA;
	polygonLayout[1].InstanceDataStepRate = 0;

	polygonLayout[2].SemanticName = "NORMAL";
	polygonLayout[2].SemanticIndex = 0;
	polygonLayout[2].Format = DXGI_FORMAT_R32G32B32_FLOAT;
	polygonLayout[2].InputSlot = 0;
	polygonLayout[2].AlignedByteOffset = D3D10_APPEND_ALIGNED_ELEMENT;
	polygonLayout[2].InputSlotClass = D3D10_INPUT_PER_VERTEX_DATA;
	polygonLayout[2].InstanceDataStepRate = 0;

	// Get a count of the elements in the layout.
	numElements = sizeof(polygonLayout) / sizeof(polygonLayout[0]);

	// Get the description of the first pass described in the shader technique.
	m_technique->GetPassByIndex(0)->GetDesc(&passDesc);

	// Create the input layout.
	result = device->CreateInputLayout(polygonLayout, numElements, passDesc.pIAInputSignature, passDesc.IAInputSignatureSize, &m_layout);
	if(FAILED(result))
	{
		return false;
	}

	// Get pointers to the three matrices inside the shader so we can update them from this class.
	m_worldMatrixPtr = m_effect->GetVariableByName("worldMatrix")->AsMatrix();
	m_viewMatrixPtr = m_effect->GetVariableByName("viewMatrix")->AsMatrix();
	m_projectionMatrixPtr = m_effect->GetVariableByName("projectionMatrix")->AsMatrix();

	// Get pointer to the texture resource inside the shader.
	m_texturePtr = m_effect->GetVariableByName("shaderTexture")->AsShaderResource();

	// Get pointers to the light direction and diffuse color variables inside the shader.
	m_lightDirectionPtr = m_effect->GetVariableByName("lightDirection")->AsVector();

The new ambient light pointer is set to interface to the ambient color inside the light shader.

	m_ambientColorPtr = m_effect->GetVariableByName("ambientColor")->AsVector();
	m_diffuseColorPtr = m_effect->GetVariableByName("diffuseColor")->AsVector();

	return true;
}


void LightShaderClass::ShutdownShader()
{
	// Release the light pointers.
	m_lightDirectionPtr = 0;

The new ambient light pointer released in the ShutdownShader function.

	m_ambientColorPtr = 0;
	m_diffuseColorPtr = 0;

	// Release the pointer to the texture in the shader file.
	m_texturePtr = 0;

	// Release the pointers to the matrices inside the shader.
	m_worldMatrixPtr = 0;
	m_viewMatrixPtr = 0;
	m_projectionMatrixPtr = 0;

	// Release the pointer to the shader layout.
	if(m_layout)
	{
		m_layout->Release();
		m_layout = 0;
	}

	// Release the pointer to the shader technique.
	m_technique = 0;

	// Release the pointer to the shader.
	if(m_effect)
	{
		m_effect->Release();
		m_effect = 0;
	}

	return;
}


void LightShaderClass::OutputShaderErrorMessage(ID3D10Blob* errorMessage, HWND hwnd, WCHAR* shaderFilename)
{
	char* compileErrors;
	unsigned long bufferSize, i;
	ofstream fout;


	// Get a pointer to the error message text buffer.
	compileErrors = (char*)(errorMessage->GetBufferPointer());

	// Get the length of the message.
	bufferSize = errorMessage->GetBufferSize();

	// Open a file to write the error message to.
	fout.open("shader-error.txt");

	// Write out the error message.
	for(i=0; i<bufferSize; i++)
	{
		fout << compileErrors[i];
	}

	// Close the file.
	fout.close();

	// Release the error message.
	errorMessage->Release();
	errorMessage = 0;

	// Pop a message up on the screen to notify the user to check the text file for compile errors.
	MessageBox(hwnd, L"Error compiling shader.  Check shader-error.txt for message.", shaderFilename, MB_OK);

	return;
}

The SetShaderParameters function now takes in a ambient light color value. The new m_ambientColorPtr is then used to set that ambient light color value in the shader before rendering.

void LightShaderClass::SetShaderParameters(D3DXMATRIX worldMatrix, D3DXMATRIX viewMatrix, D3DXMATRIX projectionMatrix, 
					   ID3D10ShaderResourceView* texture, D3DXVECTOR3 lightDirection, D3DXVECTOR4 ambientColor, 
					   D3DXVECTOR4 diffuseColor)
{
	// Set the world matrix variable inside the shader.
	m_worldMatrixPtr->SetMatrix((float*)&worldMatrix);

	// Set the view matrix variable inside the shader.
	m_viewMatrixPtr->SetMatrix((float*)&viewMatrix);

	// Set the projection matrix variable inside the shader.
	m_projectionMatrixPtr->SetMatrix((float*)&projectionMatrix);

	// Bind the texture.
	m_texturePtr->SetResource(texture);

	// Set the direction of the light inside the shader.
	m_lightDirectionPtr->SetFloatVector((float*)&lightDirection);

	// Set the ambient color of the light.
	m_ambientColorPtr->SetFloatVector((float*)&ambientColor);

	// Set the diffuse color of the light inside the shader.
	m_diffuseColorPtr->SetFloatVector((float*)&diffuseColor);

	return;
}


void LightShaderClass::RenderShader(ID3D10Device* device, int indexCount)
{
	D3D10_TECHNIQUE_DESC techniqueDesc;
	unsigned int i;
	

	// Set the input layout.
	device->IASetInputLayout(m_layout);

	// Get the description structure of the technique from inside the shader so it can be used for rendering.
	m_technique->GetDesc(&techniqueDesc);

	// Go through each pass in the technique (should be just one currently) and render the triangles.
	for(i=0; i<techniqueDesc.Passes; ++i)
	{
		m_technique->GetPassByIndex(i)->Apply(0);
		device->DrawIndexed(indexCount, 0, 0);
	}

	return;
}

Lightclass.h

The LightClass was updated for this tutorial to have an ambient component and related helper functions.

////////////////////////////////////////////////////////////////////////////////
// Filename: lightclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _LIGHTCLASS_H_
#define _LIGHTCLASS_H_


//////////////
// INCLUDES //
//////////////
#include <d3dx10math.h>


////////////////////////////////////////////////////////////////////////////////
// Class name: LightClass
////////////////////////////////////////////////////////////////////////////////
class LightClass
{
public:
	LightClass();
	LightClass(const LightClass&);
	~LightClass();

	void SetAmbientColor(float, float, float, float);
	void SetDiffuseColor(float, float, float, float);
	void SetDirection(float, float, float);

	D3DXVECTOR4 GetAmbientColor();
	D3DXVECTOR4 GetDiffuseColor();
	D3DXVECTOR3 GetDirection();

private:
	D3DXVECTOR4 m_ambientColor;
	D3DXVECTOR4 m_diffuseColor;
	D3DXVECTOR3 m_direction;
};

#endif

Lightclass.cpp

////////////////////////////////////////////////////////////////////////////////
// Filename: lightclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "lightclass.h"


LightClass::LightClass()
{
}


LightClass::LightClass(const LightClass& other)
{
}


LightClass::~LightClass()
{
}


void LightClass::SetAmbientColor(float red, float green, float blue, float alpha)
{
	m_ambientColor = D3DXVECTOR4(red, green, blue, alpha);
	return;
}


void LightClass::SetDiffuseColor(float red, float green, float blue, float alpha)
{
	m_diffuseColor = D3DXVECTOR4(red, green, blue, alpha);
	return;
}


void LightClass::SetDirection(float x, float y, float z)
{
	m_direction = D3DXVECTOR3(x, y, z);
	return;
}


D3DXVECTOR4 LightClass::GetAmbientColor()
{
	return m_ambientColor;
}


D3DXVECTOR4 LightClass::GetDiffuseColor()
{
	return m_diffuseColor;
}


D3DXVECTOR3 LightClass::GetDirection()
{
	return m_direction;
}

Graphicsclass.h

The header for the GraphicsClass hasn't changed for this tutorial.

////////////////////////////////////////////////////////////////////////////////
// Filename: graphicsclass.h
////////////////////////////////////////////////////////////////////////////////
#ifndef _GRAPHICSCLASS_H_
#define _GRAPHICSCLASS_H_


///////////////////////
// MY CLASS INCLUDES //
///////////////////////
#include "d3dclass.h"
#include "cameraclass.h"
#include "modelclass.h"
#include "lightshaderclass.h"
#include "lightclass.h"


/////////////
// GLOBALS //
/////////////
const bool FULL_SCREEN = true;
const bool VSYNC_ENABLED = true;
const float SCREEN_DEPTH = 1000.0f;
const float SCREEN_NEAR = 0.1f;


////////////////////////////////////////////////////////////////////////////////
// Class name: GraphicsClass
////////////////////////////////////////////////////////////////////////////////
class GraphicsClass
{
public:
	GraphicsClass();
	GraphicsClass(const GraphicsClass&);
	~GraphicsClass();

	bool Initialize(int, int, HWND);
	void Shutdown();
	bool Frame();

private:
	bool Render(float);

private:
	D3DClass* m_D3D;
	CameraClass* m_Camera;
	ModelClass* m_Model;
	LightShaderClass* m_LightShader;
	LightClass* m_Light;
};

#endif

Graphicsclass.cpp

////////////////////////////////////////////////////////////////////////////////
// Filename: graphicsclass.cpp
////////////////////////////////////////////////////////////////////////////////
#include "graphicsclass.h"


GraphicsClass::GraphicsClass()
{
	m_D3D = 0;
	m_Camera = 0;
	m_Model = 0;
	m_LightShader = 0;
	m_Light = 0;
}


GraphicsClass::GraphicsClass(const GraphicsClass& other)
{
}


GraphicsClass::~GraphicsClass()
{
}


bool GraphicsClass::Initialize(int screenWidth, int screenHeight, HWND hwnd)
{
	bool result;


	// Create the Direct3D object.
	m_D3D = new D3DClass;
	if(!m_D3D)
	{
		return false;
	}

	// Initialize the Direct3D object.
	result = m_D3D->Initialize(screenWidth, screenHeight, VSYNC_ENABLED, hwnd, FULL_SCREEN, SCREEN_DEPTH, SCREEN_NEAR);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize Direct3D.", L"Error", MB_OK);
		return false;
	}

	// Create the camera object.
	m_Camera = new CameraClass;
	if(!m_Camera)
	{
		return false;
	}

	// Set the initial position of the camera.
	m_Camera->SetPosition(0.0f, 0.0f, -10.0f);
	
	// Create the model object.
	m_Model = new ModelClass;
	if(!m_Model)
	{
		return false;
	}

	// Initialize the model object.
	result = m_Model->Initialize(m_D3D->GetDevice(), "../Engine/data/cube.txt", L"../Engine/data/seafloor.dds");
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize the model object.", L"Error", MB_OK);
		return false;
	}

	// Create the light shader object.
	m_LightShader = new LightShaderClass;
	if(!m_LightShader)
	{
		return false;
	}

	// Initialize the light shader object.
	result = m_LightShader->Initialize(m_D3D->GetDevice(), hwnd);
	if(!result)
	{
		MessageBox(hwnd, L"Could not initialize the light shader object.", L"Error", MB_OK);
		return false;
	}

	// Create the light object.
	m_Light = new LightClass;
	if(!m_Light)
	{
		return false;
	}

Set the intensity of the ambient light to 15% white color. Also set the direction of the light to point down the positive X axis so we can directly see the effect of ambient lighting on the cube.

	// Initialize the light object.
	m_Light->SetAmbientColor(0.15f, 0.15f, 0.15f, 1.0f);
	m_Light->SetDiffuseColor(1.0f, 1.0f, 1.0f, 1.0f);
	m_Light->SetDirection(1.0f, 0.0f, 0.0f);

	return true;
}


void GraphicsClass::Shutdown()
{
	// Release the light object.
	if(m_Light)
	{
		delete m_Light;
		m_Light = 0;
	}

	// Release the light shader object.
	if(m_LightShader)
	{
		m_LightShader->Shutdown();
		delete m_LightShader;
		m_LightShader = 0;
	}

	// Release the model object.
	if(m_Model)
	{
		m_Model->Shutdown();
		delete m_Model;
		m_Model = 0;
	}

	// Release the camera object.
	if(m_Camera)
	{
		delete m_Camera;
		m_Camera = 0;
	}

	// Release the D3D object.
	if(m_D3D)
	{
		m_D3D->Shutdown();
		delete m_D3D;
		m_D3D = 0;
	}

	return;
}


bool GraphicsClass::Frame()
{
	bool result;
	static float rotation = 0.0f;

I have slowed down the rotation by half so the effect is easier to see.

	// Update the rotation variable each frame.
	rotation += (float)D3DX_PI * 0.005f;
	if(rotation > 360.0f)
	{
		rotation -= 360.0f;
	}

	// Render the graphics scene.
	result = Render(rotation);
	if(!result)
	{
		return false;
	}

	return true;
}


bool GraphicsClass::Render(float rotation)
{
	D3DXMATRIX worldMatrix, viewMatrix, projectionMatrix;


	// Clear the buffers to begin the scene.
	m_D3D->BeginScene(0.0f, 0.0f, 0.0f, 1.0f);

	// Generate the view matrix based on the camera's position.
	m_Camera->Render();

	// Get the world, view, and projection matrices from the camera and d3d objects.
	m_Camera->GetViewMatrix(viewMatrix);
	m_D3D->GetWorldMatrix(worldMatrix);
	m_D3D->GetProjectionMatrix(projectionMatrix);

	// Rotate the world matrix by the rotation value so that the triangle will spin.
	D3DXMatrixRotationY(&worldMatrix, rotation);

	// Put the model vertex and index buffers on the graphics pipeline to prepare them for drawing.
	m_Model->Render(m_D3D->GetDevice());

The light shader now takes in as input the ambient color of the light.

	// Render the model using the light shader.
	m_LightShader->Render(m_D3D->GetDevice(), m_Model->GetIndexCount(), worldMatrix, viewMatrix, projectionMatrix, m_Model->GetTexture(),
			      m_Light->GetDirection(), m_Light->GetAmbientColor(), m_Light->GetDiffuseColor());
	
	// Present the rendered scene to the screen.
	m_D3D->EndScene();

	return true;
}

Summary

With the addition of ambient lighting all surfaces now illuminate to a minimum degree to produce a more realistic lighting effect.


To Do Exercises

1. Recompile the code and ensure you get a spinning cube that is illuminated on the dark side now.

2. Change the ambient light value to (0.0f, 0.0f, 0.0f, 1.0f) to see just the diffuse component again.

3. Comment out the color = color * textureColor; line in the pixel shader to see just the lighting effect.


Source Code

Visual Studio 2010 Project: dx10tut09.zip

Source Only: dx10src09.zip

Executable Only: dx10exe09.zip

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