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Changing the shape of our light |
OK, we’ve got a square light, casting shadows on our scene. How can we make it look more like a real light? A real light shines a round beam of light, so let’s start with that. To determine the pixels that are part of the round beam, we could add some (difficult?) mathematical checks. That would be OK for a normal light, but for the headlights of a car? This should have 2 beams, so more maths..
In my opinion, a much easier method is to throw in another texture that can be used by our pixel shader:
By looking at the image above I think you get the idea: only the white part will be lit. You can download it by right-clicking on it or by clicking here. We can already add the texture sampler to our HLSL code:
Texture xCarLightTexture;
sampler CarLightSampler = sampler_state { texture = <xCarLightTexture>
; magfilter = LINEAR; minfilter=LINEAR; mipfilter = LINEAR; AddressU = clamp; AddressV = clamp;};
Now we can simply sample the color value of this image, which gives us a value between 0 and 1. We simply need to multiply our final color by this value, so this is the core of your pixel shader:
float LightTextureFactor = tex2D(CarLightSampler, ProjectedTexCoords).r;
float DiffuseLightingFactor = DotProduct(xLightPos, PSIn.Position3D, PSIn.Normal);
float4 ColorComponent = tex2D(ColoredTextureSampler, PSIn.TexCoords);
Output.Color = ColorComponent*LightTextureFactor*DiffuseLightingFactor*xLightPower;
That’s it for the HLSL code! In our DirectX code, we’re going to load the texture file, as well as this one, which we’ll be using for our lampposts:
Which you can also download here here. First we’ll need to declare these 2 variables:
private Texture CarLight;
private Texture PointLight;
And load the image files into them in your FillResources method:
CarLight = TextureLoader.FromFile(device, "carlight.jpg");
SpotLight = TextureLoader.FromFile(device, "spotlight.jpg");
effect.SetValue("xCarLightTexture", CarLight);
The last line passes the resource on to our HLSL code.
Et voila! That’s all there is to it. You should see the image below:
Click here to go to the forum on this chapter!
Try changing the CarLight to a SpotLight, you’ll see how easy it is to change the shape of our light. You can also use shaping images with other values than completely white/black. Grey pixels will be lit with less light than white pixels!
The HLSL code:
struct SMapVertexToPixel
{
float4 Position : POSITION;
float3 Position2D : TEXCOORD0;
};
struct SMapPixelToFrame
{
float4 Color : COLOR0;
};
struct SSceneVertexToPixel
{
float4 Position : POSITION;
float4 ShadowMapSamplingPos : TEXCOORD0;
float4 RealDistance : TEXCOORD1;
float2 TexCoords : TEXCOORD2;
float3 Normal : TEXCOORD3;
float3 Position3D : TEXCOORD4;
};
struct SScenePixelToFrame
{
float4 Color : COLOR0;
};
//------- Constants --------
float4x4 xWorldViewProjection;
float4x4 xLightWorldViewProjection;
float4x4 xRot;
float4 xLightPos;
float xLightPower;
float xMaxDepth;
//------- Texture Samplers --------
Texture xColoredTexture;
sampler ColoredTextureSampler = sampler_state { texture = <xColoredTexture>
; magfilter = LINEAR; minfilter = LINEAR; mipfilter=LINEAR; AddressU = mirror; AddressV = mirror;};
Texture xShadowMap;
sampler ShadowMapSampler = sampler_state { texture = <xShadowMap>
; magfilter = LINEAR; minfilter = LINEAR; mipfilter=LINEAR; AddressU = clamp; AddressV = clamp;};
Texture xCarLightTexture;
sampler CarLightSampler = sampler_state { texture = <xCarLightTexture>
; magfilter = LINEAR; minfilter=LINEAR; mipfilter = LINEAR; AddressU = clamp; AddressV = clamp;};
//------- Vertex Shaders --------
SMapVertexToPixel ShadowMapVertexShader( float4 inPos : POSITION)
{
SMapVertexToPixel Output = (SMapVertexToPixel)0;
Output.Position = mul(inPos, xLightWorldViewProjection);
Output.Position2D = Output.Position;
return Output;
}
SSceneVertexToPixel ShadowedSceneVertexShader( float4 inPos : POSITION, float2 inTexCoords : TEXCOORD0, float3 inNormal : NORMAL)
{
SSceneVertexToPixel Output = (SSceneVertexToPixel)0;
Output.Position = mul(inPos, xWorldViewProjection);
Output.ShadowMapSamplingPos = mul(inPos, xLightWorldViewProjection);
Output.RealDistance = Output.ShadowMapSamplingPos.z/xMaxDepth;
Output.TexCoords = inTexCoords;
Output.Normal = mul(inNormal, xRot);
Output.Position3D = inPos;
return Output;
}
//------- Pixel Shaders --------
float DotProduct(float4 LightPos, float3 Pos3D, float3 Normal)
{
float3 LightDir = normalize(LightPos - Pos3D);
return dot(LightDir, Normal);
}
SMapPixelToFrame ShadowMapPixelShader(SMapVertexToPixel PSIn)
{
SMapPixelToFrame Output = (SMapPixelToFrame)0;
Output.Color = PSIn.Position2D.z/xMaxDepth;
return Output;
}
SScenePixelToFrame ShadowedScenePixelShader(SSceneVertexToPixel PSIn)
{
SScenePixelToFrame Output = (SScenePixelToFrame)0;
float2 ProjectedTexCoords;
ProjectedTexCoords[0] = PSIn.ShadowMapSamplingPos.x/PSIn.ShadowMapSamplingPos.w/2.0f +0.5f;
ProjectedTexCoords[1] = -PSIn.ShadowMapSamplingPos.y/PSIn.ShadowMapSamplingPos.w/2.0f +0.5f;
if ((saturate(ProjectedTexCoords.x) == ProjectedTexCoords.x) && (saturate(ProjectedTexCoords.y) == ProjectedTexCoords.y))
{
float StoredDepthInShadowMap = tex2D(ShadowMapSampler, ProjectedTexCoords).x;
if ((PSIn.RealDistance.x - 1.0f/100.0f) <= StoredDepthInShadowMap)
{
float LightTextureFactor = tex2D(CarLightSampler, ProjectedTexCoords).r;
float DiffuseLightingFactor = DotProduct(xLightPos, PSIn.Position3D, PSIn.Normal);
float4 ColorComponent = tex2D(ColoredTextureSampler, PSIn.TexCoords);
Output.Color = ColorComponent*LightTextureFactor*DiffuseLightingFactor*xLightPower;
}
}
return Output;
}
//------- Techniques --------
technique ShadowMap
{
pass Pass0
{
VertexShader = compile vs_2_0 ShadowMapVertexShader();
PixelShader = compile ps_2_0 ShadowMapPixelShader();
}
}
technique ShadowedScene
{
pass Pass0
{
VertexShader = compile vs_2_0 ShadowedSceneVertexShader();
PixelShader = compile ps_2_0 ShadowedScenePixelShader();
}
}
And the DirectX code:
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using Microsoft.DirectX;
using Microsoft.DirectX.Direct3D;
using D3D = Microsoft.DirectX.Direct3D;
namespace DirectX_Tutorial
{
struct myownvertexformat
{
public Vector3 Pos;
public Vector3 Normal;
public Vector2 TexCoord;
public myownvertexformat(Vector3 _Pos, Vector3 _Normal, float texx, float texy)
{
Pos = _Pos;
Normal = _Normal;
TexCoord.X = texx;
TexCoord.Y = texy;
}
}
public class WinForm : System.Windows.Forms.Form
{
private System.ComponentModel.Container components = null;
private D3D.Device device;
private VertexBuffer vb;
private Vector3 CameraPos;
private VertexDeclaration vd;
private Effect effect;
private Texture StreetTexture;
private Texture CarLight;
private Texture SpotLight;
private Mesh Lamppost;
private Material[] LamppostMaterials;
private Texture[] LamppostTextures;
private Mesh Car;
private Material[] CarMaterials;
private Texture[] CarTextures;
private Matrix matView;
private Matrix matProjection;
private Matrix LightViewProjection;
private int LastTickCount = 1;
private int Frames = 0;
private float LastFrameRate = 0;
private D3D.Font text;
private RenderToSurface RtsHelper;
private Texture RenderTexture;
private Surface RenderSurface;
private int RenderSurfaceSize = 512;
public WinForm()
{
InitializeComponent();
this.SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.Opaque, true);
}
public void InitializeDevice()
{
PresentParameters presentParams = new PresentParameters();
presentParams.Windowed = true;
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.AutoDepthStencilFormat = DepthFormat.D16;
presentParams.EnableAutoDepthStencil = true;
Caps DevCaps = D3D.Manager.GetDeviceCaps(0, D3D.DeviceType.Hardware);
D3D.DeviceType DevType = D3D.DeviceType.Reference;
CreateFlags DevFlags = CreateFlags.SoftwareVertexProcessing;
if ((DevCaps.VertexShaderVersion >= new Version(2, 0)) && (DevCaps.PixelShaderVersion >= new Version(2, 0)))
{
DevType = D3D.DeviceType.Hardware;
if (DevCaps.DeviceCaps.SupportsHardwareTransformAndLight)
{
DevFlags = CreateFlags.HardwareVertexProcessing;
if (DevCaps.DeviceCaps.SupportsPureDevice)
{
DevFlags |= CreateFlags.PureDevice;
}
}
}
device = new D3D.Device(0, DevType, this, DevFlags, presentParams);
device.DeviceReset += new EventHandler(this.HandleDeviceReset);
}
private void HandleDeviceReset(object sender, EventArgs e)
{
FillResources();
}
private void AllocateResources()
{
vb = new VertexBuffer(typeof(myownvertexformat), 18, device, Usage.WriteOnly, VertexFormats.Position | VertexFormats.Normal | VertexFormats.Texture0, Pool.Managed);
InitializeFont();
effect = D3D.Effect.FromFile(device, @"../../OurHLSLFile.fx", null, null, ShaderFlags.None, null);
}
private void FillResources()
{
myownvertexformat[] vertices = new myownvertexformat[18];
vertices[0] = new myownvertexformat(new Vector3(20, -10, 0), new Vector3(0, 0, 1), -0.25f, 25.0f);
vertices[1] = new myownvertexformat(new Vector3(20, 100, 0), new Vector3(0, 0, 1), -0.25f, 0.0f);
vertices[2] = new myownvertexformat(new Vector3(-2, -10, 0), new Vector3(0, 0, 1), 0.25f, 25.0f);
vertices[3] = new myownvertexformat(new Vector3(-2, 100, 0), new Vector3(0, 0, 1), 0.25f, 0.0f);
vertices[4] = new myownvertexformat(new Vector3(-2, -10, 0), new Vector3(1, 0, 0), 0.25f, 25.0f);
vertices[5] = new myownvertexformat(new Vector3(-2, 100, 0), new Vector3(1, 0, 0), 0.25f, 0.0f);
vertices[6] = new myownvertexformat(new Vector3(-2, -10, 1), new Vector3(1, 0, 0), 0.375f, 25.0f);
vertices[7] = new myownvertexformat(new Vector3(-2, 100, 1), new Vector3(1, 0, 0), 0.375f, 0.0f);
vertices[8] = new myownvertexformat(new Vector3(-2, -10, 1), new Vector3(0, 0, 1), 0.375f, 25.0f);
vertices[9] = new myownvertexformat(new Vector3(-2, 100, 1), new Vector3(0, 0, 1), 0.375f, 0.0f);
vertices[10] = new myownvertexformat(new Vector3(-3, -10, 1), new Vector3(0, 0, 1), 0.5f, 25.0f);
vertices[11] = new myownvertexformat(new Vector3(-3, 100, 1), new Vector3(0, 0, 1), 0.5f, 0.0f);
vertices[12] = new myownvertexformat(new Vector3(-13, -10, 1), new Vector3(0, 0, 1), 0.75f, 25.0f);
vertices[13] = new myownvertexformat(new Vector3(-13, 100, 1), new Vector3(0, 0, 1), 0.75f, 0.0f);
vertices[14] = new myownvertexformat(new Vector3(-13, -10, 1), new Vector3(1, 0, 0), 0.75f, 25.0f);
vertices[15] = new myownvertexformat(new Vector3(-13, 100, 1), new Vector3(1, 0, 0), 0.75f, 0.0f);
vertices[16] = new myownvertexformat(new Vector3(-13, -10, 21), new Vector3(1, 0, 0), 1.25f, 25.0f);
vertices[17] = new myownvertexformat(new Vector3(-13, 100, 21), new Vector3(1, 0, 0), 1.25f, 0.0f);
vb.SetData(vertices, 0, LockFlags.None);
SetUpCamera();
VertexElement[] velements = new VertexElement[]
{
new VertexElement(0, 0, DeclarationType.Float3, DeclarationMethod.Default, DeclarationUsage.Position, 0),
new VertexElement(0, 12, DeclarationType.Float3, DeclarationMethod.Default, DeclarationUsage.Normal, 0),
new VertexElement(0, 24, DeclarationType.Float2, DeclarationMethod.Default, DeclarationUsage.TextureCoordinate, 0),
VertexElement.VertexDeclarationEnd
};
vd = new VertexDeclaration(device, velements);
StreetTexture = TextureLoader.FromFile(device, "streettexture.jpg");
CarLight = TextureLoader.FromFile(device, "carlight.jpg");
SpotLight = TextureLoader.FromFile(device, "spotlight.jpg");
effect.SetValue("xColoredTexture", StreetTexture);
LoadMesh("lamppost.x", ref Lamppost, ref LamppostMaterials, ref LamppostTextures);
LoadMesh("car.x", ref Car, ref CarMaterials, ref CarTextures);
RtsHelper = new RenderToSurface(device, RenderSurfaceSize, RenderSurfaceSize, Format.X8R8G8B8, true, DepthFormat.D16);
RenderTexture = new Texture(device, RenderSurfaceSize, RenderSurfaceSize, 1, Usage.RenderTarget, Format.X8R8G8B8, Pool.Default);
RenderSurface = RenderTexture.GetSurfaceLevel(0);
}
private void InitializeFont()
{
System.Drawing.Font systemfont = new System.Drawing.Font("Arial", 12f, FontStyle.Regular);
text = new D3D.Font(device, systemfont);
}
private void DrawMesh(Mesh mesh, Material[] meshmaterials, Texture[] meshtextures)
{
for (int i = 0; i < meshmaterials.Length; i++)
{
if (meshtextures.Length > 3) effect.SetValue("xColoredTexture", meshtextures[i]);
effect.CommitChanges();
mesh.DrawSubset(i);
}
}
protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
{
UpdateLightData();
GenerateShadowMap();
device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.Black, 1.0f, 0);
device.BeginScene();
RenderShadowedScene();
using (Sprite spriteobject = new Sprite(device))
{
spriteobject.Begin(SpriteFlags.DoNotSaveState);
spriteobject.Transform = Matrix.Scaling(0.25f, 0.25f, 0.25f);
spriteobject.Draw(RenderTexture, new Rectangle(0, 0, RenderSurfaceSize, RenderSurfaceSize), new Vector3(0, 0, 0), new Vector3(0, 0, 0), Color.White);
spriteobject.End();
}
UpdateFramerate();
device.EndScene();
device.Present();
this.Invalidate();
}
private void GenerateShadowMap()
{
RtsHelper.BeginScene(RenderSurface);
device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.Black, 1.0f, 0);
effect.Technique = "ShadowMap";
effect.SetValue("xMaxDepth", 60);
int numpasses = effect.Begin(0);
for (int i = 0; i < numpasses; i++)
{
effect.BeginPass(i);
DrawScene();
effect.EndPass();
}
effect.End();
RtsHelper.EndScene(Filter.None);
}
private void RenderShadowedScene()
{
effect.Technique = "ShadowedScene";
effect.SetValue("xShadowMap", RenderTexture);
effect.SetValue("xCarLightTexture", CarLight);
int numpasses = effect.Begin(0);
for (int i = 0; i < numpasses; i++)
{
effect.BeginPass(i);
DrawScene();
effect.EndPass();
}
effect.End();
}
private void UpdateLightData()
{
Vector3 LightPos = new Vector3(18, 2, 5);
float LightPower = 2f;
LightViewProjection = Matrix.LookAtLH(LightPos, new Vector3(2, 10, -3), new Vector3(0, 0, 1)) * Matrix.PerspectiveFovLH((float)Math.PI / 2, this.Width / this.Height, 1f, 100f);
effect.SetValue("xLightPos", new Vector4(LightPos.X, LightPos.Y, LightPos.Z, 1));
effect.SetValue("xLightPower", LightPower);
}
private void DrawScene()
{
effect.SetValue("xWorldViewProjection", Matrix.Identity * matView * matProjection);
effect.SetValue("xLightWorldViewProjection", Matrix.Identity * LightViewProjection);
effect.SetValue("xRot", Matrix.Identity);
effect.SetValue("xColoredTexture", StreetTexture);
effect.CommitChanges();
device.SetStreamSource(0, vb, 0);
device.VertexDeclaration = vd;
device.DrawPrimitives(PrimitiveType.TriangleStrip, 0, 16);
Matrix LamppostWorld = Matrix.Scaling(0.05f, 0.05f, 0.05f) * Matrix.RotationX((float)Math.PI / 2) * Matrix.Translation(-4.0f, 5, 1);
effect.SetValue("xWorldViewProjection", LamppostWorld * matView * matProjection);
effect.SetValue("xLightWorldViewProjection", LamppostWorld * LightViewProjection);
effect.SetValue("xRot", Matrix.RotationX((float)Math.PI / 2));
effect.CommitChanges();
DrawMesh(Lamppost, LamppostMaterials, LamppostTextures);
LamppostWorld = Matrix.Scaling(0.05f, 0.05f, 0.05f) * Matrix.RotationX((float)Math.PI / 2) * Matrix.Translation(-4.0f, 35, 1);
effect.SetValue("xWorldViewProjection", LamppostWorld * matView * matProjection);
effect.SetValue("xLightWorldViewProjection", LamppostWorld * LightViewProjection);
effect.SetValue("xRot", Matrix.RotationX((float)Math.PI / 2));
effect.CommitChanges();
DrawMesh(Lamppost, LamppostMaterials, LamppostTextures);
Matrix CarWorld = Matrix.Scaling(4f, 4f, 4f) * Matrix.RotationYawPitchRoll((float)Math.PI / 2, (float)Math.PI / 2, (float)Math.PI / 2) * Matrix.Translation(3, 15, 0f);
effect.SetValue("xWorldViewProjection", CarWorld * matView * matProjection);
effect.SetValue("xLightWorldViewProjection", CarWorld * LightViewProjection);
effect.SetValue("xRot", Matrix.RotationYawPitchRoll((float)Math.PI / 2, (float)Math.PI / 2, (float)Math.PI / 2) * Matrix.Translation(3, 15, 0f));
DrawMesh(Car, CarMaterials, CarTextures);
CarWorld = Matrix.Scaling(4f, 4f, 4f) * Matrix.RotationYawPitchRoll((float)Math.PI / 2, (float)Math.PI / 8, (float)Math.PI / 2) * Matrix.Translation(28, -1.9f, 0f);
effect.SetValue("xWorldViewProjection", CarWorld * matView * matProjection);
effect.SetValue("xLightWorldViewProjection", CarWorld * LightViewProjection);
effect.SetValue("xRot", Matrix.RotationYawPitchRoll((float)Math.PI / 2, (float)Math.PI / 2, (float)Math.PI / 2) * Matrix.Translation(3, 15, 0f));
DrawMesh(Car, CarMaterials, CarTextures);
}
private void UpdateFramerate()
{
Frames++;
if (Math.Abs(Environment.TickCount - LastTickCount) > 1000)
{
LastFrameRate = (float)Frames * 1000 / Math.Abs(Environment.TickCount - LastTickCount);
LastTickCount = Environment.TickCount;
Frames = 0;
}
text.DrawText(null, string.Format("Framerate : {0:0.00} fps", LastFrameRate), new Point(10, 430), Color.Red);
}
private void SetUpCamera()
{
CameraPos = new Vector3(25, -18, 13);
matProjection = Matrix.PerspectiveFovLH((float)Math.PI / 4, this.Width / this.Height, 0.3f, 200f);
matView = Matrix.LookAtLH(CameraPos, new Vector3(0, 12, 2), new Vector3(0, 0, 1));
}
private void LoadMesh(string filename, ref Mesh mesh, ref Material[] meshmaterials, ref Texture[] meshtextures)
{
ExtendedMaterial[] materialarray;
GraphicsStream adj = null;
mesh = Mesh.FromFile(filename, MeshFlags.Managed, device, out adj, out materialarray);
if ((materialarray != null) && (materialarray.Length > 0))
{
meshmaterials = new Material[materialarray.Length];
meshtextures = new Texture[materialarray.Length];
for (int i = 0; i < materialarray.Length; i++)
{
meshmaterials[i] = materialarray[i].Material3D;
meshmaterials[i].Ambient = meshmaterials[i].Diffuse;
if ((materialarray[i].TextureFilename != null) && (materialarray[i].TextureFilename != string.Empty))
{
meshtextures[i] = TextureLoader.FromFile(device, materialarray[i].TextureFilename);
}
}
}
mesh = mesh.Clone(mesh.Options.Value, CustomVertex.PositionNormalTextured.Format, device);
mesh.ComputeNormals();
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose(disposing);
}
private void InitializeComponent()
{
this.components = new System.ComponentModel.Container();
this.Size = new System.Drawing.Size(500, 500);
this.Text = "Riemer's DirectX & HLSL Tutorial using C# -- Season 3";
}
static void Main()
{
using (WinForm our_directx_form = new WinForm())
{
our_directx_form.InitializeDevice();
our_directx_form.AllocateResources();
our_directx_form.FillResources();
Application.Run(our_directx_form);
}
}
}
}
- Website design & XNA + DirectX code : Riemer Grootjans -
©2003 - 2011 Riemer Grootjans
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