실시간 레이트레이싱과 게임의 미래

1. 실시간 레이트레이싱과 게임의 미래실시간 레이트레이싱과 게임의 미래
김성완

2. Ray Tracing 의 과거
• [1968] Arthur Appel
– “Some techniques for shading machine renderings of
solids”
– Basic ray casting with shadows
• [1980] Turnur Whitted
– “An Improved Illumination Model for Shaded Display”
• Reflection
• Refraction
• Shadows
• Hidden Surface Removal
• [1984] Lucas Film
• [1986] Eric Graham, Amiga

3. [1980] First Ray tracing

4. [1984] Lucas film

5. [1986] Amiga Sculpt3d

6. Ray Tracing 의 현재
• POV-Ray
– Persistence of Vision Raytracer
– Freeware multi-platform ray-tracing
package.
– http://www.povray.org/

7. POV-Ray Hall of Fame

8. POV-Ray Hall of Fame

9. POV-Ray Hall of Fame

10. POV-Ray Hall of Fame

11. POV-Ray Hall of Fame

12. POV-Ray Hall of Fame

13. POV-Ray Hall of Fame??

14. Ray Tracing?

15. Ray Tracing?
eye
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eye
a bs0
e fs2 c bs1
R T
R R TT

16. Raytracing Is Simple
• Paul Heckbert wrote a raytracer that fits on a business card!
typedef struct{double x,y,z}vec;vec U,black,amb={.02,.02,.02};struct sphere{ vec cen,color;double
rad,kd,ks,kt,kl,ir}*s,*best,sph[]={0.,6.,.5,1.,1.,1.,.9, .05,.2,.85,0.,1.7,-
1.,8.,-.5,1.,.5,.2,1.,.7,.3,0.,.05,1.2,1.,8.,-.5,.1,.8,.8, 1.,.3,.7,0.,0.,1.2,3.,-
6.,15.,1.,.8,1.,7.,0.,0.,0.,.6,1.5,-3.,-3.,12.,.8,1., 1.,5.,0.,0.,0.,.5,1.5,};yx;double
u,b,tmin,sqrt(),tan();double vdot(A,B)vec A ,B;{return A.x*B.x+A.y*B.y+A.z*B.z;}vec
vcomb(a,A,B)double a;vec A,B;{B.x+=a* A.x;B.y+=a*A.y;B.z+=a*A.z;return B;}vec vunit(A)vec A;
{return vcomb(1./sqrt( vdot(A,A)),A,black);}struct sphere*intersect(P,D)vec P,D;
{best=0;tmin=1e30;s= sph+5;while(s-->sph)b=vdot(D,U=vcomb(-1.,P,s->cen)),u=b*b-vdot(U,U)
+s->rad*s ->rad,u=u>0?sqrt(u):1e31,u=b-u>1e-7?b-u:b+u,tmin=u>=1e-7&&u<tmin?best=s,u:
tmin;return best;}vec trace(level,P,D)vec P,D;{double d,eta,e;vec N,color; struct sphere*s,*l;if(!
level--)return black;if(s=intersect(P,D));else return amb;color=amb;eta=s->ir;d=
-vdot(D,N=vunit(vcomb(-1.,P=vcomb(tmin,D,P),s->cen )));if(d<0)N=vcomb(-
1.,N,black),eta=1/eta,d= -d;l=sph+5;while(l-->sph)if((e=l ->kl*vdot(N,U=vunit(vcomb(-1.,P,l-
>cen))))>0&&intersect(P,U)==l)color=vcomb(e ,l->color,color);U=s-
>color;color.x*=U.x;color.y*=U.y;color.z*=U.z;e=1-eta* eta*(1-d*d);return vcomb(s->kt,e>0?
trace(level,P,vcomb(eta,D,vcomb(eta*d-sqrt (e),N,black))):black,vcomb(s-
>ks,trace(level,P,vcomb(2*d,N,D)),vcomb(s->kd, color,vcomb(s->kl,U,black))));}main(){printf("%d
%dn",32,32);while(yx<32*32) U.x=yx%32-32/2,U.z=32/2-yx+
+/32,U.y=32/2/tan(25/114.5915590261),U=vcomb(255., trace(3,black,vunit(U)),black),printf("%.0f
%.0f %.0fn",U);}/*minray!*/

17. Raytracing is SLOW
• 1024 * 768 = 786,432 rays
• 1280 * 1024 = 1,310,720 rays
• 1920 * 1080 = 2,073,600 rays
– Full HD 해상도

18. Escher

19. H/W 의 발전
• GPU
– Nvidia, ATI
• CPU
– Intel, AMD

20. NVIDIA

21. NVIDIA

22. ATI

23. ATI

24. ATI

25. INTEL

26. INTEL

27. AMD

28. AMD Phenom™ 9600 Quad
Core

29. Multi Core CPU 의 발전

30. WOW

31. ATI Radeon HD4800

32. ATI Radeon HD4800

33. 등장인물들

34. M&A

35. Real-Time Ray Tracing
• 실시간 레이트레이싱 가능
• OpenRT
– Real-Time Ray-Tracing Project
– http://www.openrt.de/
– The OpenRT project originated from the
RTRT realtime-raytracing project of the
University of Saarbruecken (
http://graphics.cs.uni-sb.de).

36. Q3RT

37. Q3RT

38. Q3RT

39. Q4RT

40. Linear Scaling

41. Daniel Pohl -> Intel

42. Project Offset -> Intel

43. Nvidia
• David Kirk
– http://rssoo.tistory.com/7055
• RayScale - Interactive Ray Tracing

44. Pov-Ray 3.7 real-time
Raytracing

45. Pov-Ray 3.7 real-time
Raytracing

46. Rasterization VS Raytracing

47. John Carmack
• PC Perspective - John Carmack on id Tech 6
, Ray Tracing, Consoles
– http://www.pcper.com/article.php?aid=532

48. Tim Sweeney
• Ray-tracing is a cool direction for future rendering techniques.
• Rendering can be done on the CPU. As soon as we have enough
CPU cores and better vector support, these schemes might get
more practical for games. And: As GPUs become more general, you
will have the possibility of writing a rendering engine that runs
directly on the GPU and bypasses DirectX as well as the graphics
pipeline.

49. Simple Real Time Ray tracing Demo

50. 수학

51. Code
• void RayTracer::Render(int scan)
• {
• Vector3 vRay, vPoint;
• Vector3 InterPos, vNormal, vLight;
• float intensity;
• unsigned offset;
• WORD color565;
• int index = 0;
•
• if (scan%2) offset = BytesPerScanline;
• else {offset = 0;}
• for (int y = scan; y < SCREEN_HEIGHT; y+= 2)
• {
• for (int x = 0; x < SCREEN_WIDTH; x++)
• {
• // make incident view ray
• vRay = MakeRay(x - SCREEN_WIDTH/2, SCREEN_HEIGHT/2 - y, 256);
•
• Ray ViewRay;
• ViewRay.dir = vRay;
• ViewRay.startp = Vector3(0.0f, 0.0f, 0.0f);
• float Intensity = 0;
•
• intensity = RayTrace(ViewRay, &InterPos, &vNormal);
• if (intensity < 0.0f) {offset += 2; continue;}
• Intensity += intensity;
•

52. • /////////////////////////////////
• ///// Reflection
• float R_Factor = 0.4f;
• if (true) {
• Vector3 vReflect = vNormal * (-ViewRay.dir * vNormal) * 2 + ViewRay.dir;
•
• Ray R_ray(InterPos, vReflect);
• intensity = RayTrace(R_ray, &InterPos, &vNormal);
• if (intensity < 0.0f) {goto DRAWPIXEL;}
• Intensity += intensity * R_Factor;
• }
• DRAWPIXEL:
• if ( Intensity > 1.0f ) Intensity = 1.0f;
• if ( Intensity < 0.0f ) Intensity = 0.0f;
• // Draw Pixel
• BYTE B,G,R;
• BYTE color = BYTE(Intensity * 255);
• B = color;
• G = color;
• R = color;
• color565 = R >> 3 << 11;
• color565 |= G >> 2 << 5;
• color565 |= B >> 3;
• *(WORD*)(pBits + offset) = color565;
• offset += 2;
•
• }
• offset += BytesPerScanline;
• }
• }

53. 미래는 ?
• Intel
– Larabee
• AMD, ATI
– Fusion
• Nvidia
– CUDA