OpenGL Programming – Day 1 Young-Min Kang Tongmyong Univ.

Introduction to OpenGL What is OpenGL? Software interface to graphics hardware Open Graphics Library Free Platform independent OpenGL is a library Set of functions OpenGL is platform independent No window management

OpenGL vs. DirectX OpenGL DirectX Advantage of OpenGL Platform independent DirectX Optimized for MS-Windows on PC Advantage of OpenGL Compatibility Advantage of DirectX Optimized Performance

OpenGL

Basic OpenGL Programming OpenGL Source Code #include <WhateverYouNeed.h> main () { InitializeWindowPlease(); glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0f, 1.0f, 1.0f); glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0); glBegin(GL_POLYGON); glVertex3f(0.25, 0.25, 0.0); glVertex3f(0.75, 0.25, 0.0); glVertex3f(0.75, 0.75, 0.0); glVertex3f(0.25, 0.75, 0.0); glEnd(); glFlush(); }

OpenGL Utilities OpenGL provides GLU GLUT A small set of geometric primitives Points, lines, and polygons GLU GL Utilities: modeling and viewing manipulation GLUT A simple windowing API

OpenGL Programming Conventions OpenGL conventions OpenGL Commands Starts with gl- prefix Suffix conventions {2|3|4}{s|i|f|d}[v] 2, 3, 4 determines the dimension s: short / i: integer / f: float / d: double v: array type glVertex3f(0.3, 1.0, 0.0); float vertex[3] = { 0.3, 1.0, 0.0 }; glVertex3fv(vertex);

OpenGL Programming Conventions OpenGL coordinates – Homogeneous coordinate glVertex2f(1, 2);  (1,2,0,1) glVertex3f(1, 2, 0);  (1,2,0,1) glVertex4f(1, 2, 0, 1);  (1,2,0,1) OpenGL as a state machine OpenGL is a state machine States can be turned on or off Rendering conditions are set and maintained until changed

OpenGL Programming Document Resources Programming guide http://www.opengl.org/documentation/red_book_1.0/ Reference manual http://www.rush3d.com/reference/opengl-bluebook-1.0/ What is needed for OpenGL Programming Headers: Gl.h, glu.h Libraries: Opengl32.lib, glut32.lib DLLs: Opengl32.lib, glu32.lib Optional headers and libraries: Glaux.h, glaux.lib / glut.h, glut32.lib, glut32.dll

GLUT download GLUT – The OpenGL Utility Toolkit Why GLUT is needed http://www.opengl.org/resources/libraries/glut.html http://www.xmission.com/~nate/glut.html Why GLUT is needed OpenGL has no methods to manage windows GLUT Window system independent toolkit for writing OpenGL program A simple windowing application programming interface GLUT makes it extremely easy to learn OpenGL programming

GLUT installation GLUT GLUT.h GLUT32.lib GLUT32.dll [$include]/GL/ GLUT32.lib [$lib]/ GLUT32.dll C:\Windows\System

OpenGL Programming OpenGL programming with GLUT MS Visual Studio .Net Environments Where are the OpenGL headers and libraries Headers Microsoft Visual Studio .Net 2003\Vc7\PlatformSDK\Include\gl Gl.h, glu.h, glaux.h Libraries Microsoft Visual Studio .Net 2003\Vc7\PlatformSDK\Lib Opengl32.lib, glu32.lib, glaux.lib Copy glut files to proper directories Glut.h  …\Vc7\PlatformSDK\Include\gl Glut32.lib  …\Vc7\PlatformSDK\Lib Glut32.dll  C:\Windows\System

OpenGL programming Simple Program Create win32 console project

OpenGL programming Menu: Project  Properties (Linker  input) Additional Dependency Opengl32.lib glu32.lib glaux.lib glut32.lib

OpenGL programming Add a source code item

OpenGL Programming with GLUT Headers #include <windows.h> #include <gl/gl.h> #include <gl/glut.h> Function prototypes void display(void); OpenGL display function void init(void); OpenGL initialization function

OpenGL Programming with GLUT Main function int main(int argc, char **argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE|GLUT_RGBA); glutInitWindowSize(250, 250); glutInitWindowPosition(100,100); glutCreateWindow("My First OpenGL Program"); init(); glutDisplayFunc(display); glutMainLoop(); return 0; }

OpenGL Programming with GLUT Initialization Function void init(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0); } glClearColor Determines the color to be used for clearing buffer glMatrixMode Determines which matrix would be changed Projection matrix / Model_View matrix LoadIdentity Loads identity matrix glOrtho Sets an orthogonal projection matrix

OpenGL Programming with GLUT OpenGL display function void display(void) { glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0f, 1.0f, 1.0f); glBegin(GL_POLYGON); glVertex3f(0.25, 0.25, 0.0); glVertex3f(0.75, 0.25, 0.0); glVertex3f(0.75, 0.75, 0.0); glVertex3f(0.25, 0.75, 0.0); glEnd(); glFlush(); }

OpenGL and Win32 OpenGL in MS-Windows OpenGL is platform independent No window management APIs What is needed Option 1 – using GLUT Easy window management Platform independent Disadvantage Console based Option 2 – using Win32 API Perfectly integrated into MS-windows environments Platform dependent Increased complexity in coding

OpenGL and Win32 OpenGL with Win32 Properly include headers and link libraries Get device context Win32 API Set pixel format Create rendering context WGL API is needed Write your own OpenGL code

OpenGL and Win32 Headers and libraries Option 1: GLUT Option 2: Win32 Gl.h / glu.h / glut.h Libraries Opengl32.lib / glu32.lib / glut32.lib Option 2: Win32 Glut.h/.lib/.dll are not necessary

OpenGL and Win32 Device context (DC) How to get a DC? An object which both holds information about a device and provides a way to use the device. Properties DCs refer to an internal data structure in Windows DCs are not accessible to applications programs can only reference device context via a handle How to get a DC? Use GetDC(HWND) function in Win32 API How to release the current DC? Use ReleaseDC(HWND, HDC) function in Win32 API

OpenGL and Win32 Device Context Pixel format Obtaining a DC HDC hDC = GetDC(hWnd); Release the DC ReleaseDC(hDC); Pixel format We need to set the pixel format for the DC Informs the system how we are going to use the DC Whether Double buffering will be used or not Whether Z-buffer will be used or not Which color format will be used …

OpenGL and Win32 Pixel format PIXELFORMATDESCRIPTOR pfd; ZeroMemory( &pfd, sizeof(pfd) ); pfd.nSize = sizeof(pfd); pfd.nVersion = 1; pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_GL | PFD_DOUBLEBUFFER; pfd.iPixelType = PFD_TYPE_RGBA; pfd.cColorBits = 24; pfd.cDepthBits = 16; pfd.iLayerType = PFD_MAIN_PLANE; int iFormat = ChoosePixelFormat(hDC, &pfd); SetPixelFormat(hDC, iFormat, &pfd);

OpenGL and Win32 Render Context How to manipulate GL render context A bridge to the OpenGL program HGLRC Handle of GL render context How to manipulate GL render context WGL Creation of GL render context HGLRC hRC; hRC = wglCreateContext(hDC); Deletion of GL render context wglDeleteContext(hRC);

OpenGL and Win32 Current RC Storing old DC and RC Multiple instances of GL RC can run simultaneously Which one is current one? Making a RC current wglMakeCurrent(hDC, hRC); Making a RC not current wglMakeCurrent(NULL, NULL); Storing old DC and RC HDC hOldDC = wglGetCurrentDC(); HDC hOldRC = wglGetCurrentContext(); … wglMakeCurrent(hOldDC, hOldRC);

Win32 Programming Create an empty Win32 project

Win32 Programming Write a simple Win32 program #include <windows.h> HWND Win32Init(HINSTANCE hInst,HINSTANCE hPrev,LPSTR szCmdLine, int sw); void Render(HWND hwnd, HDC hDC); LONG WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam); int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR lpCmdLine, int nCmdShow) { MSG msg; if (!Win32Init(hInst,hPrev,lpCmdLine, nCmdShow)) return FALSE; while(true) { if (PeekMessage(&msg, 0, 0, 0, PM_REMOVE)) { if (msg.message == WM_QUIT) break; TranslateMessage(&msg); DispatchMessage(&msg); } return msg.wParam;

Win32 Programming Win32 Initialization Routine HWND Win32Init( HINSTANCE hInst, HINSTANCE hPrev, LPSTR szCmdLine, int nCmdShow); RegisterClass CreateWindow

Win32 Programming BOOL Win32Init(HINSTANCE hInst, HINSTANCE hPrev, LPSTR szCmdLine, int nCmdShow) { WNDCLASS WindowClass; BOOL bSuccess; char szWndName[] = "Very Simple W32 Application - Young-Min Kang"; char szClsName[] = "VSW32Class"; if (!hPrev) { WindowClass.hCursor = LoadCursor(0,IDC_ARROW); WindowClass.hIcon = LoadIcon(NULL,IDI_APPLICATION); WindowClass.lpszMenuName = NULL; WindowClass.lpszClassName = szClsName; WindowClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH); WindowClass.hInstance = hInst; WindowClass.style = CS_BYTEALIGNCLIENT | CS_VREDRAW | CS_HREDRAW; WindowClass.lpfnWndProc = (WNDPROC)WndProc; WindowClass.cbClsExtra = 0; WindowClass.cbWndExtra = 0; bSuccess = RegisterClass(&WindowClass); if(!bSuccess) return NULL; }

Win32 Programming HWND hWnd = CreateWindow ( szClsName, // Class name szWndName // Window Title /* Window Style */ WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | WS_MAXIMIZEBOX | WS_MINIMIZEBOX, 100, 100 // Window Position 512, 512, // Window size 0, // Parent 0, // Class Menu hInst, // Handle to Window Instance 0 //Additional Parameter ); ShowWindow(hWnd, nCmdShow); // display the window return hWnd; }

Win32 Programming WndProc Window procedure that handles message events LONG WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam) { static int x[2], y[2]; HDC hDC = GetDC(hwnd); switch (msg) { case WM_CLOSE: DestroyWindow(hwnd); return FALSE; case WM_DESTROY: PostQuitMessage(0); break; case WM_LBUTTONDOWN: x[0] = LOWORD(lParam); y[0] = HIWORD(lParam); break; case WM_LBUTTONUP: x[1] = LOWORD(lParam); y[1] = HIWORD(lParam); MoveToEx(hDC,x[0],y[0],NULL); LineTo(hDC,x[1],y[1]); ReleaseDC(hwnd,hDC); break; case WM_PAINT: Render(hwnd, hDC); break; } return DefWindowProc(hwnd,msg,wParam,lParam);

OpenGL Programming with Win32 Link libraries

OpenGL Programming with Win32 Include headers #include <windows.h> #include <GL/gl.h> #include <GL/glu.h> OpenGL headers must be proceeded by window.h New functions for OpenGL rendering void OpenGLDisplay(void); void OpenGLInit(void);

OpenGL Programming with Win32 OpenGL Manager class COpenGLManager { public: HWND m_hWnd; HDC m_hDC; HGLRC m_hGLRC; COpenGLManager() { m_hWnd = NULL; m_hDC = NULL; m_hGLRC = NULL; } ~COpenGLManager() { StopGL(); void StartGL(HWND hWnd); void StopGL(void); };

OpenGL Programming with Win32 OpenGL enabling method void COpenGLManager::StartGL(HWND hWnd) { m_hDC = GetDC(m_hWnd = hWnd); PIXELFORMATDESCRIPTOR pfd; ZeroMemory( &pfd, sizeof(pfd)); pfd.nSize = sizeof(pfd); pfd.nVersion = 1; pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER; pfd.iPixelType = PFD_TYPE_RGBA; pfd.cColorBits = 24; pfd.cDepthBits = 16; pfd.iLayerType = PFD_MAIN_PLANE; int pixelFormat = ChoosePixelFormat(m_hDC, &pfd); SetPixelFormat(m_hDC, pixelFormat, &pfd); m_hGLRC = wglCreateContext(m_hDC); wglMakeCurrent(m_hDC, m_hGLRC); }

OpenGL Programming with Win32 OpenGL disabling method void COpenGLManager:: StopGL(void) { wglMakeCurrent(NULL, NULL); if(m_hGLRC) wglDeleteContext(m_hGLRC); if(m_hWnd && m_hDC) ReleaseDC(m_hWnd, m_hDC); } Declaring an OpenGL Manager instance COpenGLManager OGLMan;

OpenGL Programming with Win32 Insert OpenGL-related codes int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrev, LPSTR lpCmdLine, int nCmdShow) { MSG msg; HWND hWnd; if (! (hWnd = Win32Init(hInst,hPrev,lpCmdLine, nCmdShow))) return FALSE; OGLMan.StartGL(hWnd); OpenGLInit(); while(true) { if (PeekMessage(&msg, 0, 0, 0, PM_REMOVE)) { if (msg.message == WM_QUIT) break; TranslateMessage(&msg); DispatchMessage(&msg); } Render(OGLMan.m_hWnd, OGLMan.m_hDC); OGLMan.StopGL(); return msg.wParam;

OpenGL Programming with Win32 Modify the render function void Render(HWND hwnd, HDC hDC) { OpenGLDisplay(); SwapBuffers(hDC); } Modify the window procedure LONG WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam) { HDC hDC = GetDC(hwnd); switch (msg) { case WM_CLOSE: OGLMan.StopGL(); DestroyWindow(hwnd); return FALSE; case WM_DESTROY: PostQuitMessage(0); break; return DefWindowProc(hwnd,msg,wParam,lParam);

OpenGL Programming with Win32 OpenGL codes void OpenGLDisplay(void) { glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glClear(GL_COLOR_BUFFER_BIT); glColor3f(1.0f, 1.0f, 1.0f); glBegin(GL_POLYGON); glVertex3f(-0.75, -0.75, 0.0); glVertex3f( 0.75, -0.75, 0.0); glVertex3f( 0.75, 0.75, 0.0); glVertex3f(-0.75, 0.75, 0.0); glEnd(); } void OpenGLInit(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glMatrixMode(GL_PROJECTION); glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);