wrapped diffuse
DESCRIPTION
Wrapped Diffuse. 이민웅 Shader Study. Wrapped Diffuse. 팀 포트리스 2 에서 사용 subsurface scattering, area light source, 더 부드러운 reflectance 를 표현하기 위해서 Hemisphere( 반구 ) 를 감싸는 셰이딩 모델. Lambert. Wrapped Diffuse. Wrapped Diffuse . HarfLambert 공식과 비슷함 W=1 이면 , Half Lambert 공식 - PowerPoint PPT PresentationTRANSCRIPT
Wrapped Diffuse
이민웅Shader Study
Wrapped Diffuse• 팀 포트리스 2 에서 사용• subsurface scattering, area light
source, 더 부드러운 reflectance 를 표현하기 위해서 Hemisphere( 반구 ) 를 감싸는 셰이딩 모델
Lambert Wrapped Diffuse
Wrapped Diffuse • HarfLambert 공식과 비슷함–W=1 이면 , Half Lambert 공식
• Half Lambert 와 유사하게 투과되는 느낌을 표현하는데 많이 사용–피부 , 나뭇잎 , 파티클 라이팅에 주로 사용
기본 Lambert Diffuse 공식float diffuse = max(0, dot(normal, lightdirection));
기본 HalfLambert Diffuse 공식float halflambert_term = dot(normal, lightdirection) * 0.5f + 0.5f
Wrapped Diffuse 공식 float diffuse = saturate((dot(normal, lightdirection) + OFFSET) / (1.0+OFFSET ));
Wrapped Diffuse
Wrapped SH 자세한 내용http://blog.selfshadow.com/2011/12/31/righting-wrap-part-1/http://blog.selfshadow.com/2012/01/07/righting-wrap-part-2/
Wrap Shadingwww.iro.umontreal.ca/~derek/files/jgt_wrap.pdf
Wrapped Diffuse • 팀 포트리스 방식–Wrapped Function 은 Half Lambert 를 이용해서 , 1D Wrapped Diffuse Texture에서 값을 얻어오는 것– GPU Gems 16. Real-Time Approximation
to Subsurface Scattering• Wrap Lighting 계산 내용을 미리 Texture 로 저장하여 사용함
http://www.sfdm.scad.edu/faculty/mkesson/vsfx419/wip/spring11/eric_kurzmack/toon.html
Lambert Half Lambert Squared Half Lambert (Not used)Warping Function
Light Color Ambient Albedo
illuminance( P, n, PI) { Ln = normalize(L); halflambert += .5*(Ln.nf)+.5; float chl = clamp(halflambert,0.01,1); accumulateMapColor = texture(warp,chl,0)*2; hlsw_clrlght += Cl*accumulateMapColor; } diffusecolor = albedocolor * (Ka + hlsw_clrlght);
WarpTex
Ka : ambientCl : LightColor
http://www.sfdm.scad.edu/faculty/mkesson/vsfx419/wip/spring11/eric_kurzmack/toon.html
Specular Fresnel Primary Specularity Rim Fresnel Rim Specular
Mixed Specular Upward Ambient RimFinal Mix
Codevector i= normalize(-I); float fres=spline((nf.i),1,1,1,.95,.6,.6);
illuminance( P, n, PI/2) { Ln = normalize(L); vector R = reflect(-Ln,nf); ridot += clamp(max(0,(R.i)),.01,.99); phngspec += (1-fres)*pow(ridot,specE); }
vector i= normalize(-I); float rimfres=pow((1-(nf.i)),2);vector i= normalize(-I);
illuminance( P, n, PI/2) { Ln = normalize(L); vector R2 = reflect(Ln,nf); ridot2 += clamp(max(0,(R2.i)),.01,.99); phngrim += rimfres*pow(ridot2,Krim); }
illuminance( P, n, PI/2) { Ln = normalize(L); vector R = reflect(-Ln,nf); vector R2 = reflect(Ln,nf); ridot += clamp(max(0,(R.i)),.01,.99); ridot2 += clamp(max(0,(R2.i)),.01,.99); phngspec += (1-fres)*pow(ridot,specE); phngrim += rimfres*pow(ridot2,Krim); phngmix += Cl*Ks*(max(phngrim,phngspec)*2); } speccolor = phngmix;
float upward = clamp((nf.vector(0,1,0)),0,1); float uprim= upward*rimfres*Kr*(Ka*5);
Ci = Oi*(diffusecolor+speccolor+uprim);
Specular Fresnel
Primary Specularity
Rim Fresnel
Rim Specular
Mixed Specular
Upward Ambient Rim
Final Mix
Q&A
참고자료• Wrap Shading :
http://www.iro.umontreal.ca/~derek/publication8.html
• Energy-Conserving Wrapped Diffuse • Wrapped Diffuse 와 팀포트리스 셰이딩 :
http://cagetu.egloos.com/5621806• 팀포트리스 셰이딩 따라해보기 :
http://cagetu.egloos.com/4212681 • Energy Conservation in Games :
http://www.rorydriscoll.com/2009/01/25/energy-conservation-in-games/
• http://www.gamedevforever.com/150• http://cagetu.egloos.com/5621806