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LightHelper.fx
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LightHelper.fx
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//***************************************************************************************
// LightHelper.fx by Frank Luna (C) 2011 All Rights Reserved.
//
// Structures and functions for lighting calculations.
//***************************************************************************************
struct DirectionalLight
{
float4 Ambient;
float4 Diffuse;
float4 Specular;
float3 Direction;
float pad;
};
struct PointLight
{
float4 Ambient;
float4 Diffuse;
float4 Specular;
float3 Position;
float Range;
float3 Att;
float pad;
};
struct SpotLight
{
float4 Ambient;
float4 Diffuse;
float4 Specular;
float3 Position;
float Range;
float3 Direction;
float Spot;
float3 Att;
float pad;
};
struct Material
{
float4 Ambient;
float4 Diffuse;
float4 Specular; // w = SpecPower
float4 Reflect;
float4 RimColor;
};
//---------------------------------------------------------------------------------------
// Computes the ambient, diffuse, and specular terms in the lighting equation
// from a directional light. We need to output the terms separately because
// later we will modify the individual terms.
//---------------------------------------------------------------------------------------
void ComputeDirectionalLight(Material mat, DirectionalLight L,
float3 normal, float3 toEye, bool useRimLight,
out float4 ambient,
out float4 diffuse,
out float4 spec,
out float4 rim)
{
// Initialize outputs.
ambient = float4(0.0f, 0.0f, 0.0f, 0.0f);
diffuse = float4(0.0f, 0.0f, 0.0f, 0.0f);
spec = float4(0.0f, 0.0f, 0.0f, 0.0f);
rim = float4(0.0f, 0.0f, 0.0f, 0.0f);
// The light vector aims opposite the direction the light rays travel.
float3 lightVec = -L.Direction;
// Add ambient term.
ambient = mat.Ambient * L.Ambient;
// Add diffuse and specular term, provided the surface is in
// the line of site of the light.
float diffuseFactor = (dot(lightVec, normal) + 1) / 2;
// Flatten to avoid dynamic branching.
[flatten]
if( diffuseFactor > 0.0f )
{
float3 v = reflect(-lightVec, normal);
float specFactor = pow(max(dot(v, toEye), 0.0f), mat.Specular.w);
diffuse = diffuseFactor * mat.Diffuse * L.Diffuse;
spec = specFactor * mat.Specular * L.Specular;
}
//lim light °è»ê
[flatten]
if (useRimLight)
{
float intensity =
pow(smoothstep(0.0f, 1.0f, 1 - max(0, dot(normal, toEye))), mat.RimColor.w);
rim = mat.RimColor * max(0, dot(toEye,-lightVec)) * intensity;
}
}
//---------------------------------------------------------------------------------------
// Computes the ambient, diffuse, and specular terms in the lighting equation
// from a point light. We need to output the terms separately because
// later we will modify the individual terms.
//---------------------------------------------------------------------------------------
void ComputePointLight(Material mat, PointLight L, float3 pos, float3 normal, float3 toEye, bool useRimLight,
out float4 ambient, out float4 diffuse, out float4 spec, out float4 rim)
{
// Initialize outputs.
ambient = float4(0.0f, 0.0f, 0.0f, 0.0f);
diffuse = float4(0.0f, 0.0f, 0.0f, 0.0f);
spec = float4(0.0f, 0.0f, 0.0f, 0.0f);
rim = float4(0.0f, 0.0f, 0.0f, 0.0f);
// The vector from the surface to the light.
float3 lightVec = L.Position - pos;
// The distance from surface to light.
float d = length(lightVec);
// Range test.
if( d > L.Range )
return;
// Normalize the light vector.
lightVec /= d;
// Ambient term.
ambient = mat.Ambient * L.Ambient;
// Add diffuse and specular term, provided the surface is in
// the line of site of the light.
float diffuseFactor = (dot(lightVec, normal) + 1) / 2;
// Flatten to avoid dynamic branching.
[flatten]
if( diffuseFactor > 0.0f )
{
float3 v = reflect(-lightVec, normal);
float specFactor = pow(max(dot(v, toEye), 0.0f), mat.Specular.w);
diffuse = diffuseFactor * mat.Diffuse * L.Diffuse;
spec = specFactor * mat.Specular * L.Specular;
}
//lim light °è»ê
[flatten]
if (useRimLight)
{
float intensity =
pow(smoothstep(0.0f, 1.0f, 1 - max(0, dot(normal, toEye))), mat.RimColor.w);
rim = mat.RimColor * max(0, dot(toEye, -lightVec)) * intensity;
}
// Attenuate
float att = 1.0f / dot(L.Att, float3(1.0f, d, d*d));
diffuse *= att;
spec *= att;
rim *= att;
}
//---------------------------------------------------------------------------------------
// Computes the ambient, diffuse, and specular terms in the lighting equation
// from a spotlight. We need to output the terms separately because
// later we will modify the individual terms.
//---------------------------------------------------------------------------------------
void ComputeSpotLight(Material mat, SpotLight L, float3 pos, float3 normal, float3 toEye, bool useRimLight,
out float4 ambient, out float4 diffuse, out float4 spec, out float4 rim)
{
// Initialize outputs.
ambient = float4(0.0f, 0.0f, 0.0f, 0.0f);
diffuse = float4(0.0f, 0.0f, 0.0f, 0.0f);
spec = float4(0.0f, 0.0f, 0.0f, 0.0f);
rim = float4(0.0f, 0.0f, 0.0f, 0.0f);
// The vector from the surface to the light.
float3 lightVec = L.Position - pos;
// The distance from surface to light.
float d = length(lightVec);
// Range test.
if( d > L.Range )
return;
// Normalize the light vector.
lightVec /= d;
// Ambient term.
ambient = mat.Ambient * L.Ambient;
// Add diffuse and specular term, provided the surface is in
// the line of site of the light.
float diffuseFactor = (dot(lightVec, normal) + 1) / 2;
// Flatten to avoid dynamic branching.
[flatten]
if( diffuseFactor > 0.0f )
{
float3 v = reflect(-lightVec, normal);
float specFactor = pow(max(dot(v, toEye), 0.0f), mat.Specular.w);
diffuse = diffuseFactor * mat.Diffuse * L.Diffuse;
spec = specFactor * mat.Specular * L.Specular;
}
//lim light °è»ê
[flatten]
if (useRimLight)
{
float intensity =
pow(smoothstep(0.0f, 1.0f, 1 - max(0, dot(normal, toEye))), mat.RimColor.w);
rim = mat.RimColor * max(0, dot(toEye, -lightVec)) * intensity;
}
// Scale by spotlight factor and attenuate.
float spot = pow(max(dot(-lightVec, L.Direction), 0.0f), L.Spot);
// Scale by spotlight factor and attenuate.
float att = spot / dot(L.Att, float3(1.0f, d, d*d));
ambient *= spot;
diffuse *= att;
spec *= att;
rim *= att;
}