試驗二_基本圖元生成算法

1、實驗二 基本圖元的生成算法一、實驗?zāi)康?、初步了解顯示窗口與視區(qū)的關(guān)系2、掌握OpengGL點、直線、多邊形的繪制3、掌握DDAft線生成算法。4、掌握Bresenham直線生成算法二、實驗環(huán)境硬件要求：PC機，主流配置，最好為獨立顯卡，顯存 512M以上。軟件環(huán)境：操作系統(tǒng)：Windows XR語言開發(fā)工具：VC6.0O三、實驗內(nèi)容與要求1、調(diào)出實驗一的源代碼運行，調(diào)整修改使得顯示窗口大小改變時，繪制的矩形大小隨之改變。如圖2-1所示。提示：(1)在main函數(shù)里添加注冊窗口變化函數(shù)glutReshapeFunc(myreshape); (放在 glutMainLoop()之前)(2)在程序

2、中添加窗口改變子函數(shù)，參數(shù) w,h為當前顯示窗口的寬和高 void myreshape(GLsizei w, GLsizei h)glViewport(0,0,w,h); /設(shè)置視區(qū)位置glMatrixMode(GL_PROJECTION);設(shè)置投影變換模式glLoadIdentity(); /調(diào)單位矩陣，清空當前矩陣堆棧if(w=h)gluOrtho2D(0,300,0,300*(GLfloat)h/(GLfloat)w); /設(shè)置裁剪窗口大小 elsegluOrtho2D(0,300*(GLfloat)w/(GLfloat)h,0,300);a)顯示窗口改變前b)顯示窗口變大后圖2-1未修

3、改前的初始源程序參考如下：/*my first program.cpp*/#include void display(void) glClear(GL_COLOR_BUFFER_BIT); / 刷新顏色緩沖區(qū)glRectf(0,0,0.5,0.5);glFlush(); /用于刷新命令隊列和緩沖區(qū)，使所有尚未被執(zhí)行的OpenG命令得到執(zhí)行void main(int argc, char* argv)glutInit(&argc, argv); /初始化 GLU1WglutInitDisplayMode(GLUT_SINGLE|GLUT_RGB); /設(shè)置顯示模式glutInitWindowSi

4、ze(100, 200);glutCreateWindow(hello); /創(chuàng)建窗口，標題為 “ hello ”glutDisplayFunc(display); /用于繪制當前窗口glutMainLoop(); /表示開始運行程序，用于程序的結(jié)尾 2、自己參照講義或教材按照自己的構(gòu)思畫二維平面圖形，修改樣本程序circle-algorithm.cpp將上面的矩形替換成自己構(gòu)思的二維平面圖形。注意頂點的順序。參考函數(shù)：(1)、點繪制舉例glPointSize(2.0) /點的大小設(shè)置glBegin(GL_POINTS);glColor3f(1.0,1.0,1.0);glVertex2f(-0

5、.5,-0.5); /頂點glColor3f(1.0,0.0,1.0);glVertex2f(-0.5,0.5);glColor3f(0.0,1.0,1.0);glVertex2f(0.5,0.5);glColor3f(1.0,1.0,0.0);glVertex2f(0.5,-0.5);glEnd()(2)、直線/三角形/四邊形繪制舉例glLineWidth(2.0);glBegin(GL_LINES);/ glBegin(GL_LINE_STRIP);/ glBegin(GL_LINE_LOOP);/ glBegin(GL_TRIANGLES);/ glBegin(GL_TRIANGLE_S

6、TRIP);/ glBegin(GL_TRIANGLE_FAN);/ glBegin(GL_QUADS);/ glBegin(GL_TRIANGLE_STRIP);glVertex2f(-0.5,0.5);glVertex2f(-0.5,-0.5);glColor3f(1.0,1.0,1.0);glVertex2f(-0.5,0.5);glColor3f(1.0,1.0,0.0);glVertex2f(0.5,-0.5);glEnd();(3)、多邊形舉例glBegin(GL_POLYGON);glVertex2f(-0.5,0.5);glVertex2f(-0.5,-0.5);glColor

7、3f(1.0,1.0,1.0);glVertex2f(0,-0.5);glColor3f(1.0,1.0,0.0);glVertex2f(0.5,-0.5);glVertex2f(0.5,0.5);glEnd();3、讀懂DDAft線生成算法偽代碼，并修改偽代碼，使之變成可行的OpenGL 代碼，驗證DDAft線生成算法。DDAft線生成偽代碼/x0,y0表示直線的起始點，x1,y1表示直線的終止點，color表示直線的繪制顏色void DDA_line(int x0, int y0, int x1, int y1,int color)int dx = x1 - x0, dy = y1 - y

8、0, k;float xIncrement , yIncrement ,steps, x = x0, y = y0; if (abs (dx) abs (dy)steps = abs (dx);else steps = abs (dy);xIncrement = (float) (dx) /steps;yIncrement = (float) (dy) /steps;for (k =0; k=1的情況，又有斜率|k|1的情況，你可 以使用學過的畫直線方法，如DD序法。閱讀樣本程序，參見circle-algorithm.cpp :附：樣本程序 circle-algoritm.cpp#includ

9、e #include #include #include / set some initial parameters, such as the center of the circle(cx,cy), the radius of the circle,int cx=150,cy=150,radius=80;void DDA_Line(int x1,int y1,int x2,int y2);void Bresenham_DrawLine(int x1,int y1,int x2,int y2);void NSidedPolygon( int n, int cx, int cy, int rad

10、ius);void Display( void );void Reshape( int w, int h);int main( int argc, char * argv)(glutInit(&argc, argv);glutInitWindowPosition(0, 0);glutInitWindowSize(window_width, window_height);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);glutCreateWindow(Circle Generation Algorithm);glutDisplayFunc(Display);glutReshapeFunc(Reshape);glutMainLoop();return 0;)void Display( void )(/* YOUR CODE HERE */glutSwapBuffers();)void Reshape( int w, int h)glMatrixMode(GL_PROJECTION);glLoadIdentity();glViewport(0, 0, w, h);gluOrtho2D(0, w, 0, h);/ glutPostRedisplay();void DDA_Line(int x1,int y1,int x2,int y2