1. Simple Improvements to LI: Shadows Image Based Lighting László Szécsi

2. Image based lighting

3. Image based lighting (IBL) CPU program Vertex shader Pixel shader Position Normal Transforms Transf. pos Reflection direction Environment map id Rasterization Interpolation Env.Map texels Interpolated Reflection direction Env.map lookup

4. IBL: vertex/fragment shaders void VertexShader( in float4 position : POSITION, in float4 normal : NORMAL, uniform float4x4 MVP : state.matrix.mvp, uniform float4x4 MV : state.matrix.modelview[0], uniform float4x4 MVIT : state.matrix.modelview.invtrans[0], out float4 hPosition : POSITION, out float3 reflectdir : TEXCOORD1 ) { hPosition = mul(MVP, position); float3 view = normalize( - mul(MV, position).xyz ); float3 normcam = normalize( mul(MVIT, normal).xyz ); refrectdir = reflect(view, normcam); } float4 FragmentShader( in float3 reflectdir : TEXCOORD1, uniform samplerCUBE envMap ) : COLOR { return texCUBE(envMap, reflectdir); }

5. Reflection of ideal mirrors: Fresnel function F || = F=F= cos  ’ - (n+k j ) cos  cos  ’+ (n+k j ) cos  2 cos  - (n+k j ) cos  ’ cos  + (n+k j ) cos  ’  ’’ n =n = sin  ’ sin  Snellius-Descartes law of refraction n = Relative speed of the wave 2

6. Simplification F F || + F  2 = if light is not polarized F  F0 + (1-F0)  (1-cos  ’) 5 F0 = (n -1) 2 + k 2 (n+1) 2 + k 2 Schlick93, Lazányi05

7. Fresnel Fragment shader float4 FragmentShader( in float3 reflectdir : TEXCOORD1, in float3 normal : TEXCOORD2, uniform float3 F0, uniform samplerCUBE envMap ) : COLOR { // Fresnel reflection reflectdir = normalize( reflectdir ); normal = normalize( normal ); float3 F = F0 + pow(1-dot(normal, reflectdir), 5) * (1-F0); float3 I = texCUBE(envMap, reflectdir); return float4( F * I, 1 ); }

8. Diffuse/Glossy reflections of IBL cos  ’