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VR – OpenGL 2D

VR – OpenGL 2D. 大綱. image 、 pixel 和 color 基本概念 OpenGL 2D functions 繪圖流程和相關 Library 遊戲和輸入控制 參考資料 Demo. image 、 pixel 和 color 基本概念. Pixel and Color. Pixel: picture element 即圖上的一點 顏色 : 可由 (Red, Green, Blue) 三原色組合，每個顏色 1 Byte ，組成全彩 (0, 0, 0) 表示黑色 (255, 0, 0) 表示紅色

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VR – OpenGL 2D

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  1. VR – OpenGL 2D

  2. 大綱 • image、pixel和color基本概念 • OpenGL 2D functions • 繪圖流程和相關Library • 遊戲和輸入控制 • 參考資料 • Demo

  3. image、pixel和color 基本概念

  4. Pixel and Color • Pixel: picture element即圖上的一點 • 顏色:可由(Red, Green, Blue)三原色組合，每個顏色1 Byte，組成全彩 (0, 0, 0) 表示黑色 (255, 0, 0) 表示紅色 (255, 255, 255) 表示白色

  5. BMP image • Image：可看成一維Pixel Array， 每個Pixel由RGB組成，共24bit • Pixel的其他表示法 lookup table

  6. OpenGL 2D function

  7. Positioning Image Primitives • glRasterPos3f( x, y, z ) • raster position transformed like geometry • 若超過viewport的邊界 會被忽略 • may need to fine tuneviewport for desiredresults Raster Position X ->

  8. OpenGL raster display draw framebuffer memory copy read glReadPixels(); glCopyPixels(); glDrawPixels()

  9. Rendering Images • glDrawPixels( width, height, format, type, pixels ) • render pixels with lower left ofimage at current raster position • numerous formats and data typesfor specifying storage in memory • best performance by using format and type that matches hardware

  10. Reading Pixels • glReadPixels( x, y, width, height, format, type, pixels ) • read pixels from specified (x,y) position in framebuffer • pixels automatically converted from framebuffer format into requested format and type • Framebuffer pixel copy • glCopyPixels( x, y, width, height, type ) • copy pixels in the frame buffer to current raster position

  11. 放大縮小 glPixelZoom() • glPixelZoom(水平軸倍數, 垂直軸倍數) • Ex: • glPixelZoom(1.0, 1.0); //不變 glPixelZoom(2.0, 2.0); //放大兩倍 glPixelZoom(0.5, 0.5); //縮小 glPixelZoom(-1.0, 1.0); //水平反轉

  12. 繪圖流程和相關Library

  13. RGBpixmap.h • #include "RGBpixmap.h“ • RGBpixmap pic; //宣告一張背景圖 • //讀檔 • pic.readBMPFile(“background.bmp”); 讀取的必須是24bit的bmp檔 • pic.nRows //int 列數 • pic.nCols //int 行數 • pic.draw() //繪圖

  14. 繪圖基本流程 • void myDisplay(void) { glClear(GL_COLOR_BUFFER_BIT); glRasterPos2i(0, 0); //繪圖的左下角 pic.draw(); //繪圖 glutSwapBuffers(); }

  15. 透明圖 RGBApixmap (232, 248, 248) • Alpha: 透明色 • RGBApixmap pic; //宣告一張具透明色圖片 • pic.setChromaKey(232, 248, 248); //將圖片中的某個顏色設為透明 • Pic.blend(); //透明圖的繪圖函式

  16. 字型設定 font.h • GLFONT *Font; //宣告 • GLFONT *FontCreate(HDC hdc, const char *typeface, int height, int weight, DWORD italic); typeface 字形名稱 height 字形高度 weight 粗體設定 italic 斜體設定 • Ex: • Font = FontCreate(wglGetCurrentDC(), "Times", 32, 0, 1);

  17. 字型顯示 font.h #include <string.h> //for sprintf(); 在display()內 char mss[30]; sprintf(mss, "Score %d", Gamescore); glColor3f(1.0, 0.0, 0.0); //設定字型顏色 glRasterPos2i(10, 450); //設定字型左下角起點 FontPrintf(Font, 1, mss);

  18. 遊戲和輸入控制

  19. Game 互動性 • 玩家藉由鍵盤或搖桿輸入，畫面會因此做反應。 • 目的?分數? • 好不好玩?

  20. 利用鍵盤輸入使圖片移動 RGBApixmap pic[3]; 在Display() glRasterPos2i(picX, picY); pic[whichPic].blend(); • 在Speckeyfunc() switch(key) { case GLUT_KEY_LEFT: picX -= 5; break; case GLUT_KEY_RIGHT: picX += 5; break; …….. } glutPostRedisplay();

  21. 換圖 • 在Speckeyfunc() case GLUT_KEY_LEFT: picX -= 5; if (whichPic==0) whichPic=1; else whichPic=0; break; case GLUT_KEY_RIGHT: picX += 5; if (whichPic==0) whichPic=1; else whichPic=0; break; 0 1

  22. 轉方向 int DirectState=0; 在Speckeyfunc() case GLUT_KEY_LEFT: picX -= 5; if (whichPic==0) whichPic=1; else whichPic=0; DirectState=1; break; case GLUT_KEY_RIGHT: …… DirectState=0; break; 在Display() if(DirectState==0) { glPixelZoom(1.0, 1.0); glRasterPos2i(picX, picY); }else { glPixelZoom(-1.0, 1.0); glRasterPos2i(picX+pic[whichPic].nCols, picY); } pic[whichPic].blend();

  23. glutTimerFunc() glutTimerFunc(int msecs, (*func)(int value), int value); 登記一個func，在經過msecs毫秒後呼叫，並將value值設給func Func的宣告 void jump(int i);

  24. How to use time funtion void jump(int i) { whichPic=2; //切換到jump圖片 if (i<5) picY+=4; //前五次向上移 else picY-=4; //後幾次向下移 if(i<10) { i++; glutTimerFunc( 100, jump, i); //呼叫time fution }else { whichPic=0; //回復原先狀態 jumpState=0; } glutPostRedisplay(); } 2

  25. Jump-keyfuntion case 'm': if(jumpState==0) { jumpState=1; Gamescore++; jump(0); } break;

  26. 全螢幕和Gamemode • 切換至全螢幕 和目前解析度一樣 glutFullScreen(); • 切換全螢幕 可自行設解析度 寫在case GLUT_KEY_F1:

  27. 參考資料 • GLUT 使用說明 用google查glut game第一個連結 • OpenGL 超級手冊 Ch7 • OpenGL Programming Guide Ch8 http://ask.ii.uib.no/ebt-bin/nph-dweb/dynaweb/SGI_Developer/OpenGL_PG OpenGL官方網站Http://www.opengl.org

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