Microsoft PowerPoint D View Class.pptx

Digital 3D Anthropometry 5. 3D View Class Sungmin Kim SEOUL NATIONAL UNIVERSITY 3D View Class 의설계 3 차원그래픽의개요 Introduction Surface graphics Volume graphics Lighting and shading 3차원모델을 2차원화면에표시하는클래스 Rendering Context 만들기 장면그리기 시점변환 2

Surface Graphics Polygonal Mesh 를이용해서물체의표면만을그리는방법 장면의복잡성에따라처리속도가달라짐 하드웨어가속이용이함 대부분의그래픽어플리케이션에사용됨 Computer Graphics 3 Surface Graphics 메쉬 (Mesh) 구조모델링 주로삼각형 mesh 가사용됨 vertex, edge, face 로구성 Computer Graphics face normal vector 4

Volume Graphics 복셀 (Voxel, Volume Element) 기반의모델링 장면의복잡도와관계없이일정한처리속도를가짐 확립된하드웨어가속방법이없음 Compositing 프로세스의복잡성에기인 의학분야등에사용 Computer Graphics 5 조명 중요성 장면의사실성을높여줌 어려움 다양한광원의효과 일광, 불, 전구등 물체의표면성질과색상의효과 반짝이는표면, 거친표면등 Lighting Directional (Parallel) Spot (Specular) Point Ambient (Incident) 6

정의 빛의반사를고려한색상의계산 Shading 종류 물체의mesh 의각점에대해계산 Mesh 내부의점들에대해 interpolation Flat shading Gouraud shading Phong shading Face normal vector Light Angle Triangular Element Flat Shading 7 Gouraud Shading Mesh 의각꼭지점에대해계산 Shading Barycentric Coordinate 를써서 interpolation c2 c3 a1 C a2 a3 c1 c1 a1 c2 a2 c3 a3 C a1 a2 a3 Barycentric Coordinate System 8

Phong Shading Mesh 꼭지점의 normal vector 를 interpolation Shading Interpolated normal 을이용한 shading Specular Light 에의한 highlight 이구현됨 Interpolated Normal vector 9 Global Illumination 광학현상을충실히묘사한렌더링으로매우사실적인표현이가능함 반사, 굴절, 투명도, 그림자등의표현 엄청난계산이필요함 Rendering 10

중요성 물체의복잡도를높이지않고사실성을향상할수있는방법 방법 물체의형상에맞는 2D 이미지를생성 메쉬의꼭지점에텍스쳐좌표를설정 Texture Mapping 11 OpenGL (Open Graphics Library) 의역사 1992 년실리콘그래픽스사에서만든 2 차원및 3 차원그래픽스표준규격 OpenGL 1980 년대에다양한그래픽하드웨어에맞는소프트웨어를개발하는일은매우어려웠음 소프트웨어개발자들이개별하드웨어에맞추어맞춤식인터페이스와드라이버를작성 실리콘그래픽스 (SGI) IrisGL API (Application Programming Interface) 를오픈소스로전환 프로그래밍언어간, 플랫폼간의교차응용프로그래밍을지원 마이크로소프트사의 Direct3D 와함께컴퓨터그래픽세계를양분 표준안이여러관련업체의토론과제안으로이루어지기에버전업데이트는느린편이다 비영리기술컨소시엄인크로노스그룹에의하여관리되고있다 약 250 여개의 API 함수호출을이용 특징 단순한기하도형에서부터복잡한삼차원장면까지생성가능 게임, CAD, 가상현실, 정보시각화, 비행시뮬레이션등의분야에서활용 서로다른하드웨어에대해단일한 API 를제공 하드웨어플랫폼의능력차이를보완함 12

OpenGL 의확장 OpenGL GLSL GLUT SDL GLU GLee GLEW GLUI GLFW GLM SFML GLUX OpenGL의상위레벨셰이딩언어윈도시스템에독립적인 OpenGL 프로그램을작성하도록도와주는도구 Simple DirectMedia Layer OpenGL 프로그램을위한추가적인함수를제공 OpenGL 프로그램을위한단순한추가라이브러리제공 OpenGL 확장 Wrangler 라이브러리제공 GLUT로만들어진 GUI 툴킷으로버튼, 체크박스등의 GUI 기능을제공 OpenGL 응용프로그램개발을위한이식가능한프레임워크 GLSL 규격에기반한 OpenGL을위한 C++ 수학툴킷간단하고빠른멀티미디어라이브러리 OpenGL 유틸리티및보조라이브러리 13 C++ Builder 에서 OpenGL 의작동순서 화면버퍼와같은속성의 Rendering Context 작성 OnCreate, OnResize 장면시점설정등그리기준비작업 OnPaint Rendering Context 에장면을그리기 OnPaint Rendering Context 와화면버퍼를서로바꾸기 OnPaint Rendering Context 를삭제 OnClose 14

OpenGL 의기초 Rendering Context 만들기 화면과호환되는 Pixel Format 의선택및이를바탕으로한 Rendering Context 설정 DWORD dwflags=pfd_draw_to_window PFD_SUPPORT_OPENGL PFD_DOUBLEBUFFER; PIXELFORMATDESCRIPTOR pfd= sizeof(pixelformatdescriptor), 1, dwflags, PFD_TYPE_RGBA, 24, 0,0,0,0,0,0, 0,0, 0,0,0,0,0, 24, 0, 0, PFD_MAIN_PLANE, 0, 0,0, ; PixelFormat = ChoosePixelFormat(DC, &pfd); if (PixelFormat) SetPixelFormat(DC, PixelFormat, &pfd); RC=wglCreateContext(DC); 15 OpenGL 의기초 장면그리기준비 화면의크기와종횡비등을결정하기 height XRes=GetDeviceCaps(DC,LOGPIXELSX); YRes=GetDeviceCaps(DC,LOGPIXELSY); AspectRatio=((GLfloat)Width*(GLfloat)YRes)/((GLfloat)Height*(GLfloat)XRes); (left,bottom) width 16

OpenGL 의기초 장면그리기시작 배경지우기 Depth buffer초기화 조명및재질설정 wglmakecurrent(dc,rc); glcleardepth(1); glenable(gl_depth_test); gldepthfunc(gl_lequal); glhint(gl_perspective_correction_hint, GL_NICEST); glclearaccum(0,0,0,0); gldisable(gl_cull_face); glclear(gl_color_buffer_bit GL_DEPTH_BUFFER_BIT GL_ACCUM_BUFFER_BIT); glenable( GL_COLOR_MATERIAL); glenable(gl_lighting); glenable(gl_light0); 17 OpenGL 의기초 장면그리기시작 시점및모델표시방법결정 행렬을이용한순차적변환또는명시적인지정 glmatrixmode(gl_projection); glloadidentity(); gluperspective(60.0f,aspectratio,1,10000); glmatrixmode(gl_modelview); glloadidentity(); glulookat(0,0,100,,0,0,0,0,1,0); // eye point, scene center, up vector 18

OpenGL 의기초 장면그리기종료 Rendering Context 와화면 Buffer 를바꾸기 Flicker 방지 glflush(); SwapBuffers(DC); wglmakecurrent(dc,null); OpenGL 세션종료 wglmakecurrent(dc,0); if (RC) wgldeletecontext(rc); 19 Class 설계 C++ Builder 의문제 OnCreate, OnResize, OnPaint Event 에서 Device Context 가변할수있다 #include #include #include #include <vcl.h> <gl/gl.h> <gl/glu.h> "TPoint3D.h" class public : (HDC,int,int,int,int); ~(); HDC LastDC; HGLRC RC; ; int int float void void void PixelFormat; Left,Bottom,Width,Height,XRes,YRes; AspectRatio; CreateRenderingContext(HDC); BeginDraw(HDC); EndDraw(HDC); 20

Class 설계 생성자와파괴자 ::(HDC DC,int l,int b,int r,int t) CreateRenderingContext(DC); // Rendering Context 만들기 Left=l; Bottom=b; Width=r-l; Height=t-b; XRes=GetDeviceCaps(DC,LOGPIXELSX); // 해당 Device context 의해상도구하기 YRes=GetDeviceCaps(DC,LOGPIXELSY); AspectRatio=((GLfloat)Width*(GLfloat)YRes)/((GLfloat)Height*(GLfloat)XRes); ::~() wglmakecurrent(lastdc,0); if (RC) wgldeletecontext(rc); RC=0; // 최종적으로사용된 DC 를이용 21 Class 설계 CreateRenderingContext 함수 void ::CreateRenderingContext(HDC DC) DWORD dwflags=pfd_draw_to_window PFD_SUPPORT_OPENGL PFD_DOUBLEBUFFER; PIXELFORMATDESCRIPTOR pfd= sizeof(pixelformatdescriptor), 1, dwflags, PFD_TYPE_RGBA, 24, 0,0,0,0,0,0, 0,0, 0,0,0,0,0, 24, 0, 0, PFD_MAIN_PLANE, 0, 0,0, ; PixelFormat = ChoosePixelFormat(DC, &pfd); if (PixelFormat) SetPixelFormat(DC, PixelFormat, &pfd); RC=wglCreateContext(DC); 22

Class 설계 장면그리기준비 void ::BeginDraw(HDC DC) if (!RC) return; wglmakecurrent(dc,rc); glcleardepth(1); glenable(gl_depth_test); gldepthfunc(gl_lequal); glhint(gl_perspective_correction_hint, GL_NICEST); glclearaccum(0,0,0,0); gldisable(gl_cull_face); glclear(gl_color_buffer_bit GL_DEPTH_BUFFER_BIT GL_ACCUM_BUFFER_BIT); glenable(gl_color_material); glenable(gl_lighting); glenable(gl_light0); glmatrixmode(gl_projection); glloadidentity(); gluperspective(60.0f,aspectratio,1,10000); glmatrixmode(gl_modelview); glloadidentity(); glulookat(0,0,100,0,0,0,0,1,0); // eye/center/up 23 Class 설계 장면그리기종료 void ::EndDraw(HDC DC) LastDC=DC; // 최종적으로사용한 DC를기록 glflush(); SwapBuffers(DC); wglmakecurrent(dc,null); 24

테스트프로그램개발 새프로젝트시작 SDI 프로그램을작성 TMainForm 의생성자 / 파괴자 #include ".h"... class TMainForm : public TForm... ; *GL; fastcall TMainForm::TMainForm(TComponent* Owner) : TForm(Owner) GL=0; void fastcall TMainForm::FormClose(TObject *Sender, TCloseAction &Action) if (GL) delete GL; GL=0; Action=caFree; 25 테스트프로그램개발 클래스초기화 OnCreate, OnResize event handler 작성 void fastcall TMainForm::FormCreate(TObject *Sender) GL=new (Canvas->Handle,0,0,ClientWidth,ClientHeight); void fastcall TMainForm::FormResize(TObject *Sender) if (GL) delete GL; GL=new (Canvas->Handle,0,0,ClientWidth,ClientHeight); FormPaint(this); 26

테스트프로그램개발 장면그리기 OnPaint event handler 작성 void fastcall TMainForm::FormPaint(TObject *Sender) if (GL) GL->BeginDraw(Canvas->Handle); glbegin(gl_triangles); glcolor3f(1,0,0); glnormal3f(0,0,1); glvertex3f(-10,-10,0); glvertex3f(10,-10,0); glvertex3f(0,10,0); glend(); GL->EndDraw(Canvas->Handle); 27 테스트프로그램개발 시점변환기능 회전이동 EyePoint 와 UpVector 를조절 확대축소 Scene Center 와 EyePoint 거리조절 Scene Center 와 EyePoint 위치이동 Up Vector Eye Point Scene Center 28

테스트프로그램개발 Mouse Event Handler 정의 클래스에 mouse event handler 함수를정의 void fastcall TMainForm::FormMouseDown(TObject *Sender, TMouseButton Button, TShiftState Shift, int X, int Y) if (GL) GL->MouseDown(Button,Shift,X,Y); void fastcall TMainForm::FormMouseMove(TObject *Sender, TShiftState Shift, int X, int Y) if (GL) if (GL->MouseMove(Shift,X,Y)) FormPaint(this); void fastcall TMainForm::FormMouseUp(TObject *Sender, TMouseButton Button, TShiftState Shift, int X, int Y) if (GL) GL->MouseUp(Button,Shift,X,Y); 29 테스트프로그램개발 시점변경에필요한변수및함수설정 bool DragStart; TPoint3D O_SceneCenter,O_EyePoint,O_UpVector; // 초기 viewport TPoint2D Rotation,Start; // 회전량, 마우스시작점 void CalculateViewport); // 시점계산함수 void bool void MouseDown(TMouseButton Button,TShiftState Shift, int X, int Y); MouseMove(TShiftState Shift,int X, int Y); MouseUp(TMouseButton Button,TShiftState Shift, int X, int Y); ::(HDC DC,int l,int b,int r,int t)... O_SceneCenter.Set(0,0,0); O_EyePoint.Set(0,0,100); O_UpVector.Set(0,1,0); Rotation.Set(0,0); CalculateViewport(); DragStart=false; 30

테스트프로그램개발 시점회전 void ::MouseDown(TMouseButton Button,TShiftState Shift, int X, int Y) if (!DragStart) DragStart=true; Start.Set(X,Y); // 마우스시작점 bool ::MouseMove(TShiftState Shift,int X, int Y) if (DragStart) Rotation.x+=(float)(X-Start.x)/2.0*M_PI/180.0; // 경도변화량 Rotation.y+=(float)(Y-Start.y)/2.0*M_PI/180.0; // 위도변화량 CalculateViewport(); // 시점재계산 Start.Set(X,Y); // 마우스시작점재설정 return true; return false; void ::MouseUp(TMouseButton Button,TShiftState Shift, int X, int Y) if (DragStart) DragStart=false; 31 테스트프로그램개발 시점회전 시점재계산 void ::CalculateViewport() TPoint3D O,YAxis,Normal; O.Set(0,0,0); YAxis.Set(0,1,0); // 경도방향회전 EyePoint=O_EyePoint.RotatedAbout(O_SceneCenter,YAxis,Rotation.x); UpVector=O_UpVector.RotatedAbout(O,YAxis,Rotation.x); // 위도방향회전 Normal=O_SceneCenter.CrossProduct(EyePoint,O_SceneCenter+YAxis); Normal.Normalize(); EyePoint=EyePoint.RotatedAbout(O_SceneCenter,Normal,Rotation.y); UpVector=UpVector.RotatedAbout(O,Normal,Rotation.y); 32

테스트프로그램개발 시점이동 시점이동에필요한변수추가 class... bool DragStart,Rotating; float Distance; TPoint3D O_SceneCenter,O_EyePoint,O_UpVector; TPoint2D Rotation,Start;... ::()... Distance=100; CalculateViewport(); 33 테스트프로그램개발 시점이동 시점이동에필요한코드추가 void ::MouseDown(TMouseButton Button,TShiftState Shift, int X, int Y) if (!DragStart) DragStart=true; Start.Set(X,Y); Rotating=(Button==mbLeft); 34

테스트프로그램개발 시점이동 시점이동에필요한코드추가 bool ::MouseMove(TShiftState Shift,int X, int Y) if (DragStart) if (Rotating) Rotation.x+=(float)(X-Start.x)/2.0*M_PI/180.0; Rotation.y+=(float)(Y-Start.y)/2.0*M_PI/180.0; else float dy=y-start.y; if (dy>0) Distance*=1.02f; else Distance*=0.98f; CalculateViewport(); Start.Set(X,Y); return true; return false; 35 테스트프로그램개발 시점이동 시점이동에필요한코드추가 void ::CalculateViewport() TPoint3D O,YAxis,Normal; O.Set(0,0,0); YAxis.Set(0,1,0); O_EyePoint.Set(0,0,Distance); EyePoint=O_EyePoint.RotatedAbout(O_SceneCenter,YAxis,Rotation.x); UpVector=O_UpVector.RotatedAbout(O,YAxis,Rotation.x); Normal=O_SceneCenter.CrossProduct(EyePoint,O_SceneCenter+YAxis); Normal.Normalize(); EyePoint=EyePoint.RotatedAbout(O_SceneCenter,Normal,Rotation.y); UpVector=UpVector.RotatedAbout(O,Normal,Rotation.y); 시점을상하좌우로이동하려면어떻게해야할까? (Homework) 36

테스트프로그램개발 시점초기화 메뉴를추가 void fastcall TMainForm::InitializeViewport1Click(TObject *Sender) if (GL) GL->InitViewport(100); FormPaint(this); void ::InitViewport(float dist) Distance=dist; O_SceneCenter.Set(0,0,0); O_UpVector.Set(0,1,0); Rotation.Set(0,0); CalculateViewport(); ::(HDC DC,int l,int b,int r,int t)... InitViewport(100); DragStart=false; 37