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XNA ParallaxMapping
Simon Jackson edited this page Jun 8, 2017
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1 revision
Here is a sample of using Parallax mapping in XNA using the sample shader provided in the August 2006 DirectX SDK from Microsoft (Here)
First off lsets define the assemblies we will be requiring:
using System;
using System.Xml;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Components;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Storage;Here begins the main namespace for our game:
namespace FarkleXNA
{
public class Game1 : Microsoft.Xna.Framework.Game
{Lets declare a HighPerformanceTimer.
(see the previous tutorials for explanations of these items)
HighPerformanceTimer timer;
Vector3 vCamPos;
Vector3 vCamDir;
Matrix viewMatrix, projMatrix;
Die testDie;
public Game1()
{
InitializeComponent();
}Initialize your objects in the initialize function:
protected override void Initialize()
{
timer = new HighPerformanceTimer();
vCamPos = new Vector3(1, 1,1.5f);
vCamDir = Vector3.Normalize(vCamPos);
viewMatrix = Matrix.CreateLookAt(vCamPos, Vector3.Zero, Vector3.Up);
projMatrix = Matrix.CreatePerspectiveFieldOfView(
(float)Math.PI / 2.0f,
(float)Window.ClientWidth / (float)Window.ClientHeight,
0.1f,
1000.0f);
graphics.AllowMultiSampling = false;
graphics.ApplyChanges();
testDie = new Die(graphics.GraphicsDevice);
}In the Update method you should do any per-frame calculations that are needed
protected override void Update()
{
// The time since Update was called last
float elapsed = timer.Elapsed;
// TODO: Add your game logic here
testDie.Update(elapsed);
// Let the GameComponents update
UpdateComponents();
}The draw method is where we will render the Parallax mapped dice
protected override void Draw()
{
// Make sure we have a valid device
if (!graphics.EnsureDevice())
return;
graphics.GraphicsDevice.Clear(Color.CornflowerBlue);
graphics.GraphicsDevice.BeginScene();
// TODO: Add your drawing code herePass in the current camera position, camera direction, view and projection matrices( for the shader)
testDie.Render(graphics.GraphicsDevice,
vCamPos,
vCamDir,
viewMatrix,
projMatrix);
// Let the GameComponents draw
DrawComponents();
graphics.GraphicsDevice.EndScene();
graphics.GraphicsDevice.Present();
}
}Here is the Die class for rendering dice:
public class Die
{
Texture2D[,] Textures;
public VertexBuffer vb;
static Vector3[] vNormals = new Vector3[6];
Effect effectNormalMapping;
Matrix world;
float fRot=0;Always have a dispose method to clean up any data that is created for this object
public void Dispose()
{
foreach (Texture2D tex in Textures)
tex.Dispose();
Textures = null;
vb.Dispose();
effectNormalMapping.Dispose();
}The constructor
public Die(GraphicsDevice device)
{Populate the vertices
//one
verts[0] = new VertexPosTexNormalTanBitan(
new Vector3(-1, 1, -1), new Vector2(0, 0),
new Vector3(0, 1, 0), new Vector3(1, 0, 0), new Vector3(0, 0, 1));
verts[1] = new VertexPosTexNormalTanBitan(
new Vector3(1, 1, -1), new Vector2(1, 0),
new Vector3(0, 1, 0), new Vector3(1, 0, 0), new Vector3(0, 0, 1));
verts[2] = new VertexPosTexNormalTanBitan(
new Vector3(1, 1, 1), new Vector2(1, 1),
new Vector3(0, 1, 0), new Vector3(1, 0, 0), new Vector3(0, 0, 1));
verts[3] = new VertexPosTexNormalTanBitan(
new Vector3(-1, 1, 1), new Vector2(0, 1),
new Vector3(0, 1, 0), new Vector3(1, 0, 0), new Vector3(0, 0, 1));
//two
verts[4] = new VertexPosTexNormalTanBitan(
new Vector3(1,-1,-1), new Vector2(0, 0),
new Vector3(1, 0, 0), new Vector3(0, 0, 1), new Vector3(0, 1, 0));
verts[5] = new VertexPosTexNormalTanBitan(
new Vector3(1,-1, 1), new Vector2(1, 0),
new Vector3(1, 0, 0), new Vector3(0, 0, 1), new Vector3(0, 1, 0));
verts[6] = new VertexPosTexNormalTanBitan(
new Vector3(1, 1, 1), new Vector2(1, 1),
new Vector3(1, 0, 0), new Vector3(0, 0, 1), new Vector3(0, 1, 0));
verts[7] = new VertexPosTexNormalTanBitan(
new Vector3(1, 1,-1), new Vector2(0, 1),
new Vector3(1, 0, 0), new Vector3(0, 0, 1), new Vector3(0, 1, 0));
//three
verts[8] = new VertexPosTexNormalTanBitan(
new Vector3(1, -1, 1), new Vector2(0, 0),
new Vector3(0, 0, 1), new Vector3(-1, 0, 0), new Vector3(0, 1, 0));
verts[9] = new VertexPosTexNormalTanBitan(
new Vector3(-1,-1, 1), new Vector2(1, 0),
new Vector3(0, 0, 1), new Vector3(-1, 0, 0), new Vector3(0, 1, 0));
verts[10] = new VertexPosTexNormalTanBitan(
new Vector3(-1, 1, 1), new Vector2(1, 1),
new Vector3(0, 0, 1), new Vector3(-1, 0, 0), new Vector3(0, 1, 0));
verts[11] = new VertexPosTexNormalTanBitan(
new Vector3(1, 1, 1), new Vector2(0, 1),
new Vector3(0, 0, 1), new Vector3(-1, 0, 0), new Vector3(0, 1, 0));
//four
verts[12] = new VertexPosTexNormalTanBitan(
new Vector3(-1,-1, -1), new Vector2(0, 0),
new Vector3(0, 0, -1), new Vector3(1, 0, 0), new Vector3(0, 1, 0));
verts[13] = new VertexPosTexNormalTanBitan(
new Vector3( 1,-1, -1), new Vector2(1, 0),
new Vector3(0, 0, -1), new Vector3(1, 0, 0), new Vector3(0, 1, 0));
verts[14] = new VertexPosTexNormalTanBitan(
new Vector3( 1, 1, -1), new Vector2(1, 1),
new Vector3(0, 0, -1), new Vector3(1, 0, 0), new Vector3(0, 1, 0));
verts[15] = new VertexPosTexNormalTanBitan(
new Vector3(-1, 1, -1), new Vector2(0, 1),
new Vector3(0, 0, -1), new Vector3(1, 0, 0), new Vector3(0, 1, 0));
//five
verts[16] = new VertexPosTexNormalTanBitan(
new Vector3(-1, -1, 1), new Vector2(0, 0),
new Vector3(-1, 0, 0), new Vector3(0, 0, -1), new Vector3(0, 1, 0));
verts[17] = new VertexPosTexNormalTanBitan(
new Vector3(-1, -1,-1), new Vector2(1, 0),
new Vector3(-1, 0, 0), new Vector3(0, 0, -1), new Vector3(0, 1, 0));
verts[18] = new VertexPosTexNormalTanBitan(
new Vector3(-1, 1,-1), new Vector2(1, 1),
new Vector3(-1, 0, 0), new Vector3(0, 0, -1), new Vector3(0, 1, 0));
verts[19] = new VertexPosTexNormalTanBitan(
new Vector3(-1, 1, 1), new Vector2(0, 1),
new Vector3(-1, 0, 0), new Vector3(0, 0, -1), new Vector3(0, 1, 0));
//six
verts[20] = new VertexPosTexNormalTanBitan(
new Vector3( 1, -1, -1), new Vector2(0, 0),
new Vector3(0, -1, 0), new Vector3(-1, 0, 0), new Vector3(0, 0, 1));
verts[21] = new VertexPosTexNormalTanBitan(
new Vector3(-1, -1,-1), new Vector2(1, 0),
new Vector3(0, -1, 0), new Vector3(-1, 0, 0), new Vector3(0, 0, 1));
verts[22] = new VertexPosTexNormalTanBitan(
new Vector3(-1, -1, 1), new Vector2(1, 1),
new Vector3(0, -1, 0), new Vector3(-1, 0, 0), new Vector3(0, 0, 1));
verts[23] = new VertexPosTexNormalTanBitan(
new Vector3(1, -1, 1), new Vector2(0, 1),
new Vector3(0, -1, 0), new Vector3(-1, 0, 0), new Vector3(0, 0, 1));Pre-compute the side normals so we can optimize the rendering to exclude non visible sides of the dice
for (int x = 0; x < 6; x++)
{
vNormals[x] = verts[x * 4].Normal;
}Setup the new vertex buffer and pass it the data we defined above:
vb = new VertexBuffer(device, typeof(VertexPosTexNormalTanBitan), verts.Length, BufferUsage.WriteOnly);
vb.SetData(verts);Lets load up the ParallaxOcclusionMapping effect, a new LoadContent method, along with the textures needed (see previous tutorial on HLSL effect files)
public void LoadContent(GraphicsDevice device, ContentManager content)
{
effectNormalMapping = content.Load<Effect>("ParallaxOcclusionMapping");
Textures = new Texture2D[6, 2];
for (int x = 0; x < 6; x++)
{
Textures[x, 0] = content.Load<Texture2D>("textures\\" + (x + 1).ToString());
Textures[x, 1] = content.Load<Texture2D>("textures\\" + (x + 1).ToString() + ".Normal");
}
}Initialize the Die's world transform to Identity
world = Matrix.Identity;
}On Update() I am incrementing a counter to be used to rotate the object around to see all sides of the die
public void Update(float fTime)
{
fRot += fTime;
}Heres the render method
public void Render(GraphicsDevice device,
Vector3 vCamPos,
Vector3 vCamDir,
Matrix view,
Matrix proj)
{Create a rotation matrix to spin the Die around
world = Matrix.CreateRotationZ(fRot);
world = world * Matrix.CreateRotationX((float)Math.Cos((float)fRot) * 1.5f);Set the default properties in the Effect
effectNormalMapping.Parameters["g_materialAmbientColor"].SetValue(
new Vector4(.35f, .35f, .35f, 0));
effectNormalMapping.Parameters["g_materialDiffuseColor"].SetValue(
new Vector4(1, 1, 1, 1));
effectNormalMapping.Parameters["g_materialSpecularColor"].SetValue(
new Vector4(1, 1, 1, 1));
effectNormalMapping.Parameters["g_fSpecularExponent"].SetValue(120.0f);
effectNormalMapping.Parameters["g_bAddSpecular"].SetValue(true);
effectNormalMapping.Parameters["g_LightDir"].SetValue(Vector3.Normalize(
new Vector3(0, 0, 1)));
effectNormalMapping.Parameters["g_LightDiffuse"].SetValue(
new Vector4(1, 1, 1, 1));
effectNormalMapping.Parameters["g_vEye"].SetValue(new Vector4(vCamPos, 1));
effectNormalMapping.Parameters["g_fBaseTextureRepeat"].SetValue(1.0f);
effectNormalMapping.Parameters["g_fHeightMapScale"].SetValue(0.17f);
effectNormalMapping.Parameters["g_mWorldViewProjection"].SetValue(
world * view * proj);
effectNormalMapping.Parameters["g_mWorld"].SetValue(world);
effectNormalMapping.Parameters["g_mView"].SetValue(view);
effectNormalMapping.Parameters["g_bVisualizeLOD"].SetValue(false);
effectNormalMapping.Parameters["g_bVisualizeMipLevel"].SetValue(false);
effectNormalMapping.Parameters["g_bDisplayShadows"].SetValue(true);
effectNormalMapping.Parameters["g_vTextureDims"].SetValue(
new Vector2(Textures[0, 0].Width, Textures[0, 0].Height));
effectNormalMapping.Parameters["g_nLODThreshold"].SetValue(5);
effectNormalMapping.Parameters["g_fShadowSoftening"].SetValue(0.58f);
effectNormalMapping.Parameters["g_nMinSamples"].SetValue(10);
effectNormalMapping.Parameters["g_nMaxSamples"].SetValue(100);transform the camera direction into model space for faster comparisons
Vector3 vCamDirLocal = Vector3.TransformNormal(vCamDir, Matrix.Invert(world));
for (int x = 0; x < 6; x++)
{check the angle between the camera direction and the face normal to see if it should be rendered or not
if (Vector3.Dot(vNormals[x], vCamDirLocal) < 0)
continue;This polygon is facing the camera so lets go ahead and set the diffuse and normal map's
effectNormalMapping.Parameters["g_baseTexture"].SetValue(Textures[x, 0]);
effectNormalMapping.Parameters["g_nmhTexture"].SetValue(Textures[x, 1]);
}With everything defined, all we need to do is setup the Vertex Buffer and set it drawing, as follows: Set the device's VertexDeclaration
device.SetVertexBuffer(vb);
foreach (EffectPass pass in effectNormalMapping.CurrentTechnique.Passes)
{
pass.Apply();
device.DrawPrimitives(PrimitiveType.TriangleList, 0, 12);
}
}
}ANd here is the ParallaxOcclusionMapping effect file for adding in to your content project.
#if OPENGL
#define SV_POSITION POSITION
#define VS_SHADERMODEL vs_3_0
#define PS_SHADERMODEL ps_3_0
#else
#define VS_SHADERMODEL vs_4_0_level_9_1
#define PS_SHADERMODEL ps_4_0_level_9_1
#endif
//--------------------------------------------------------------------------------------
// File: ParallaxOcclusionMapping.fx
//
// Parallax occlusion mapping implementation
//
// Implementation of the algorithm as described in "Dynamic Parallax Occlusion
// Mapping with Approximate Soft Shadows" paper, by N. Tatarchuk, ATI Research,
// to appear in the proceedings of ACM Symposium on Interactive 3D Graphics and Games, 2006.
//
// For examples of use in a real-time scene, see ATI X1K demo "ToyShop":
// http://www.ati.com/developer/demos/rx1800.html
//
// Copyright (c) ATI Research, Inc. All rights reserved.
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
// Global variables
//--------------------------------------------------------------------------------------
// Base color texture
texture g_baseTexture;
// Normal map and height map texture pair
texture g_nmhTexture;
// Material's ambient color
float4 g_materialAmbientColor;
// Material's diffuse color
float4 g_materialDiffuseColor;
// Material's specular color
float4 g_materialSpecularColor;
// Material's specular exponent
float g_fSpecularExponent;
// Toggles rendering with specular or without
bool g_bAddSpecular;
// Light parameters:
// Light's direction in world space
float3 g_LightDir;
// Light's diffuse color
float4 g_LightDiffuse;
// Light's ambient color
float4 g_LightAmbient;
// Camera's location
float4 g_vEye;
// The tiling factor for base and normal map textures
float g_fBaseTextureRepeat;
// Describes the useful range of values for the height field
float g_fHeightMapScale;
// Matrices:
// World matrix for object
float4x4 g_mWorld;
// World * View * Projection matrix
float4x4 g_mWorldViewProjection;
// View matrix
float4x4 g_mView;
// Toggles visualization of level of detail colors
bool g_bVisualizeLOD;
// Toggles visualization of mip level
bool g_bVisualizeMipLevel;
// Toggles display of self-occlusion based shadows
bool g_bDisplayShadows;
// Specifies texture dimensions for computation of mip level at
// render time (width, height)
float2 g_vTextureDims;
// The mip level id for transitioning between the full computation
// for parallax occlusion mapping and the bump mapping computation
int g_nLODThreshold;
// Blurring factor for the soft shadows computation
float g_fShadowSoftening;
// The minimum number of samples for sampling the height field profile
int g_nMinSamples;
// The maximum number of samples for sampling the height field profile
int g_nMaxSamples;
//--------------------------------------------------------------------------------------
// Texture samplers
//--------------------------------------------------------------------------------------
sampler tBase =
sampler_state
{
Texture = < g_baseTexture >;
MipFilter = LINEAR;
MinFilter = LINEAR;
MagFilter = LINEAR;
};
sampler tNormalHeightMap =
sampler_state
{
Texture = < g_nmhTexture >;
MipFilter = LINEAR;
MinFilter = LINEAR;
MagFilter = LINEAR;
};
//--------------------------------------------------------------------------------------
// Vertex shader output structure
//--------------------------------------------------------------------------------------
struct VS_OUTPUT
{
float4 position : POSITION;
float2 texCoord : TEXCOORD0;
float3 vLightTS : TEXCOORD1; // light vector in tangent space, denormalized
float3 vViewTS : TEXCOORD2; // view vector in tangent space, denormalized
float2 vParallaxOffsetTS : TEXCOORD3; // Parallax offset vector in tangent space
float3 vNormalWS : TEXCOORD4; // Normal vector in world space
float3 vViewWS : TEXCOORD5; // View vector in world space
};
//--------------------------------------------------------------------------------------
// This shader computes standard transform and lighting
//--------------------------------------------------------------------------------------
VS_OUTPUT RenderSceneVS( float4 inPositionOS : POSITION,
float2 inTexCoord : TEXCOORD0,
float3 vInNormalOS : NORMAL,
float3 vInBinormalOS : BINORMAL,
float3 vInTangentOS : TANGENT )
{
VS_OUTPUT Out;
// Transform and output input position
Out.position = mul( inPositionOS, g_mWorldViewProjection );
// Propagate texture coordinate through:
Out.texCoord = inTexCoord * g_fBaseTextureRepeat;
// Transform the normal, tangent and binormal vectors from object space
// to homogeneous projection space:
float3 vNormalWS = mul( vInNormalOS, (float3x3) g_mWorld );
float3 vTangentWS = mul( vInTangentOS, (float3x3) g_mWorld );
float3 vBinormalWS = mul( vInBinormalOS, (float3x3) g_mWorld );
// Propagate the world space vertex normal through:
Out.vNormalWS = vNormalWS;
vNormalWS = normalize( vNormalWS );
vTangentWS = normalize( vTangentWS );
vBinormalWS = normalize( vBinormalWS );
// Compute position in world space:
float4 vPositionWS = mul( inPositionOS, g_mWorld );
// Compute and output the world view vector (unnormalized):
float3 vViewWS = g_vEye - vPositionWS;
Out.vViewWS = vViewWS;
// Compute denormalized light vector in world space:
float3 vLightWS = g_LightDir;
// Normalize the light and view vectors and transform it to the tangent space:
float3x3 mWorldToTangent = float3x3( vTangentWS, vBinormalWS, vNormalWS );
// Propagate the view and the light vectors (in tangent space):
Out.vLightTS = mul( vLightWS, mWorldToTangent );
Out.vViewTS = mul( mWorldToTangent, vViewWS );
// Compute the ray direction for intersecting the height field profile with
// current view ray. See the above paper for derivation of this computation.
// Compute initial parallax displacement direction:
float2 vParallaxDirection = normalize( Out.vViewTS.xy );
// The length of this vector determines the furthest amount of displacement:
float fLength = length( Out.vViewTS );
float fParallaxLength = sqrt( fLength * fLength -
Out.vViewTS.z * Out.vViewTS.z ) / Out.vViewTS.z;
// Compute the actual reverse parallax displacement vector:
Out.vParallaxOffsetTS = vParallaxDirection * fParallaxLength;
// Need to scale the amount of displacement to account for different height ranges
// in height maps. This is controlled by an artist-editable parameter:
Out.vParallaxOffsetTS *= g_fHeightMapScale;
return Out;
}
//--------------------------------------------------------------------------------------
// Pixel shader output structure
//--------------------------------------------------------------------------------------
struct PS_OUTPUT
{
float4 RGBColor : COLOR0; // Pixel color
};
struct PS_INPUT
{
float2 texCoord : TEXCOORD0;
float3 vLightTS : TEXCOORD1; // light vector in tangent space, denormalized
float3 vViewTS : TEXCOORD2; // view vector in tangent space, denormalized
float2 vParallaxOffsetTS : TEXCOORD3; // Parallax offset vector in tangent space
float3 vNormalWS : TEXCOORD4; // Normal vector in world space
float3 vViewWS : TEXCOORD5; // View vector in world space
};
//--------------------------------------------------------------------------------------
// Function: ComputeIllumination
//
// Description: Computes phong illumination for the given pixel using its attribute
// textures and a light vector.
//--------------------------------------------------------------------------------------
float4 ComputeIllumination( float2 texCoord, float3 vLightTS,
float3 vViewTS, float fOcclusionShadow )
{
// Sample the normal from the normal map for the given texture sample:
float3 vNormalTS = normalize( tex2D( tNormalHeightMap, texCoord ) * 2 - 1 );
// Sample base map:
float4 cBaseColor = tex2D( tBase, texCoord );
// Compute diffuse color component:
float3 vLightTSAdj = float3( vLightTS.x, -vLightTS.y, vLightTS.z );
float4 cDiffuse = saturate( dot( vNormalTS, vLightTSAdj )) * g_materialDiffuseColor;
// Compute the specular component if desired:
float4 cSpecular = 0;
if ( g_bAddSpecular )
{
float3 vReflectionTS = normalize( 2 * dot( vViewTS, vNormalTS ) * vNormalTS - vViewTS );
float fRdotL = saturate( dot( vReflectionTS, vLightTSAdj ));
cSpecular = saturate( pow( fRdotL, g_fSpecularExponent )) * g_materialSpecularColor;
}
// Composite the final color:
float4 cFinalColor = (( g_materialAmbientColor + cDiffuse ) *
cBaseColor + cSpecular ) * fOcclusionShadow;
return cFinalColor;
}
//--------------------------------------------------------------------------------------
// Parallax occlusion mapping pixel shader
//
// Note: this shader contains several educational modes that would not be in the final
// game or other complicated scene rendering. The blocks of code in various "if"
// statements for turning off visual qualities (such as visual level of detail
// or specular or shadows, etc), can be handled differently, and more optimally.
// It is implemented here purely for educational purposes.
//--------------------------------------------------------------------------------------
float4 RenderScenePS( PS_INPUT i ) : COLOR0
{
// Normalize the interpolated vectors:
float3 vViewTS = normalize( i.vViewTS );
float3 vViewWS = normalize( i.vViewWS );
float3 vLightTS = normalize( i.vLightTS );
float3 vNormalWS = normalize( i.vNormalWS );
float4 cResultColor = float4( 0, 0, 0, 1 );
// Adaptive in-shader level-of-detail system implementation. Compute the
// current mip level explicitly in the pixel shader and use this information
// to transition between different levels of detail from the full effect to
// simple bump mapping. See the above paper for more discussion of the approach
// and its benefits.
// Compute the current gradients:
float2 fTexCoordsPerSize = i.texCoord * g_vTextureDims;
// Compute all 4 derivatives in x and y in a single instruction to optimize:
float2 dxSize, dySize;
float2 dx, dy;
float4( dxSize, dx ) = ddx( float4( fTexCoordsPerSize, i.texCoord ) );
float4( dySize, dy ) = ddy( float4( fTexCoordsPerSize, i.texCoord ) );
float fMipLevel;
float fMipLevelInt; // mip level integer portion
float fMipLevelFrac; // mip level fractional amount for blending in between levels
float fMinTexCoordDelta;
float2 dTexCoords;
// Find min of change in u and v across quad: compute du and dv magnitude across quad
dTexCoords = dxSize * dxSize + dySize * dySize;
// Standard mipmapping uses max here
fMinTexCoordDelta = max( dTexCoords.x, dTexCoords.y );
// Compute the current mip level (* 0.5 is effectively computing a square root before )
fMipLevel = max( 0.5 * log2( fMinTexCoordDelta ), 0 );
// Start the current sample located at the input texture coordinate, which would correspond
// to computing a bump mapping result:
float2 texSample = i.texCoord;
// Multiplier for visualizing the level of detail (see notes for 'nLODThreshold' variable
// for how that is done visually)
float4 cLODColoring = float4( 1, 1, 3, 1 );
float fOcclusionShadow = 1.0;
if ( fMipLevel <= (float) g_nLODThreshold )
{
//===============================================//
// Parallax occlusion mapping offset computation //
//===============================================//
// Utilize dynamic flow control to change the number of samples per ray
// depending on the viewing angle for the surface. Oblique angles require
// smaller step sizes to achieve more accurate precision for computing displacement.
// We express the sampling rate as a linear function of the angle between
// the geometric normal and the view direction ray:
int nNumSteps = (int) lerp( g_nMaxSamples, g_nMinSamples, dot( vViewWS, vNormalWS ) );
// Intersect the view ray with the height field profile along the direction of
// the parallax offset ray (computed in the vertex shader. Note that the code is
// designed specifically to take advantage of the dynamic flow control constructs
// in HLSL and is very sensitive to specific syntax. When converting to other examples,
// if still want to use dynamic flow control in the resulting assembly shader,
// care must be applied.
//
// In the below steps we approximate the height field profile as piecewise linear
// curve. We find the pair of endpoints between which the intersection between the
// height field profile and the view ray is found and then compute line segment
// intersection for the view ray and the line segment formed by the two endpoints.
// This intersection is the displacement offset from the original texture coordinate.
// See the above paper for more details about the process and derivation.
//
float fCurrHeight = 0.0;
float fStepSize = 1.0 / (float) nNumSteps;
float fPrevHeight = 1.0;
float fNextHeight = 0.0;
int nStepIndex = 0;
bool bCondition = true;
float2 vTexOffsetPerStep = fStepSize * i.vParallaxOffsetTS;
float2 vTexCurrentOffset = i.texCoord;
float fCurrentBound = 1.0;
float fParallaxAmount = 0.0;
float2 pt1 = 0;
float2 pt2 = 0;
float2 texOffset2 = 0;
while ( nStepIndex < nNumSteps )
{
vTexCurrentOffset -= vTexOffsetPerStep;
// Sample height map which in this case is stored in the alpha channel of the normal map:
fCurrHeight = tex2Dgrad( tNormalHeightMap, vTexCurrentOffset, dx, dy ).a;
fCurrentBound -= fStepSize;
if ( fCurrHeight > fCurrentBound )
{
pt1 = float2( fCurrentBound, fCurrHeight );
pt2 = float2( fCurrentBound + fStepSize, fPrevHeight );
texOffset2 = vTexCurrentOffset - vTexOffsetPerStep;
nStepIndex = nNumSteps + 1;
fPrevHeight = fCurrHeight;
}
else
{
nStepIndex++;
fPrevHeight = fCurrHeight;
}
}
float fDelta2 = pt2.x - pt2.y;
float fDelta1 = pt1.x - pt1.y;
float fDenominator = fDelta2 - fDelta1;
// SM 3.0 requires a check for divide by zero, since that operation will generate
// an 'Inf' number instead of 0, as previous models (conveniently) did:
if ( fDenominator == 0.0f )
{
fParallaxAmount = 0.0f;
}
else
{
fParallaxAmount = (pt1.x * fDelta2 - pt2.x * fDelta1 ) / fDenominator;
}
float2 vParallaxOffset = i.vParallaxOffsetTS * (1 - fParallaxAmount );
// The computed texture offset for the displaced point on the pseudo-extruded surface:
float2 texSampleBase = i.texCoord - vParallaxOffset;
texSample = texSampleBase;
// Lerp to bump mapping only if we are in between, transition section:
cLODColoring = float4( 1, 1, 1, 1 );
if ( fMipLevel > (float)(g_nLODThreshold - 1) )
{
// Lerp based on the fractional part:
fMipLevelFrac = modf( fMipLevel, fMipLevelInt );
if ( g_bVisualizeLOD )
{
// For visualizing: lerping from regular POM-resulted color
// through blue color for transition layer:
cLODColoring = float4( 1, 1, max( 1, 2 * fMipLevelFrac ), 1 );
}
// Lerp the texture coordinate from parallax occlusion mapped
// coordinate to bump mapping
// smoothly based on the current mip level:
texSample = lerp( texSampleBase, i.texCoord, fMipLevelFrac );
}
if ( g_bDisplayShadows == true )
{
float2 vLightRayTS = vLightTS.xy * g_fHeightMapScale;
// Compute the soft blurry shadows taking into account self-occlusion for
// features of the height field:
float sh0 = tex2Dgrad( tNormalHeightMap, texSampleBase, dx, dy ).a;
float shA = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.88, dx, dy ).a - sh0 - 0.88 ) * 1 * g_fShadowSoftening;
float sh9 = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.77, dx, dy ).a - sh0 - 0.77 ) * 2 * g_fShadowSoftening;
float sh8 = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.66, dx, dy ).a - sh0 - 0.66 ) * 4 * g_fShadowSoftening;
float sh7 = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.55, dx, dy ).a - sh0 - 0.55 ) * 6 * g_fShadowSoftening;
float sh6 = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.44, dx, dy ).a - sh0 - 0.44 ) * 8 * g_fShadowSoftening;
float sh5 = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.33, dx, dy ).a - sh0 - 0.33 ) * 10 * g_fShadowSoftening;
float sh4 = (tex2Dgrad( tNormalHeightMap, texSampleBase +
vLightRayTS * 0.22, dx, dy ).a - sh0 - 0.22 ) * 12 * g_fShadowSoftening;
// Compute the actual shadow strength:
fOcclusionShadow = 1 - max( max( max( max( max( max( shA,
sh9 ), sh8 ), sh7 ), sh6 ), sh5 ), sh4 );
// The previous computation overbrightens the image, let's adjust for that:
fOcclusionShadow = fOcclusionShadow * 0.6 + 0.4;
}
}
// Compute resulting color for the pixel:
cResultColor = ComputeIllumination( texSample, vLightTS, vViewTS, fOcclusionShadow );
if ( g_bVisualizeLOD )
{
cResultColor *= cLODColoring;
}
// Visualize currently computed mip level, tinting the color blue if we are in
// the region outside of the threshold level:
if ( g_bVisualizeMipLevel )
{
cResultColor = fMipLevel.xxxx;
}
// If using HDR rendering, make sure to tonemap the resuld color prior to outputting it.
// But since this example isn't doing that, we just output the computed result color here:
return cResultColor;
}
//--------------------------------------------------------------------------------------
// Bump mapping shader
//--------------------------------------------------------------------------------------
float4 RenderSceneBumpMapPS( PS_INPUT i ) : COLOR0
{
// Normalize the interpolated vectors:
float3 vViewTS = normalize( i.vViewTS );
float3 vLightTS = normalize( i.vLightTS );
float4 cResultColor = float4( 0, 0, 0, 1 );
// Start the current sample located at the input texture coordinate, which would correspond
// to computing a bump mapping result:
float2 texSample = i.texCoord;
// Compute resulting color for the pixel:
cResultColor = ComputeIllumination( texSample, vLightTS, vViewTS, 1.0f );
// If using HDR rendering, make sure to tonemap the resuld color prior to outputting it.
// But since this example isn't doing that, we just output the computed result color here:
return cResultColor;
}
//--------------------------------------------------------------------------------------
// Apply parallax mapping with offset limiting technique to the current pixel
//--------------------------------------------------------------------------------------
float4 RenderSceneParallaxMappingPS( PS_INPUT i ) : COLOR0
{
const float sfHeightBias = 0.01;
// Normalize the interpolated vectors:
float3 vViewTS = normalize( i.vViewTS );
float3 vLightTS = normalize( i.vLightTS );
// Sample the height map at the current texture coordinate:
float fCurrentHeight = tex2D( tNormalHeightMap, i.texCoord ).a;
// Scale and bias this height map value:
float fHeight = fCurrentHeight * g_fHeightMapScale + sfHeightBias;
// Perform offset limiting if desired:
fHeight /= vViewTS.z;
// Compute the offset vector for approximating parallax:
float2 texSample = i.texCoord + vViewTS.xy * fHeight;
float4 cResultColor = float4( 0, 0, 0, 1 );
// Compute resulting color for the pixel:
cResultColor = ComputeIllumination( texSample, vLightTS, vViewTS, 1.0f );
// If using HDR rendering, make sure to tonemap the resuld color prior to outputting it.
// But since this example isn't doing that, we just output the computed result color here:
return cResultColor;
}
//--------------------------------------------------------------------------------------
// Renders scene to render target
//--------------------------------------------------------------------------------------
technique RenderSceneWithPOM
{
pass P0
{
VertexShader = compile VS_SHADERMODEL RenderSceneVS();
PixelShader = compile PS_SHADERMODEL RenderScenePS();
}
}
technique RenderSceneWithBumpMap
{
pass P0
{
VertexShader = compile VS_SHADERMODEL RenderSceneVS();
PixelShader = compile PS_SHADERMODEL RenderSceneBumpMapPS();
}
}
technique RenderSceneWithPM
{
pass P0
{
VertexShader = compile VS_SHADERMODEL RenderSceneVS();
PixelShader = compile PS_SHADERMODEL RenderSceneParallaxMappingPS();
}
}