本文参考《Computer Graphics Using OpenGL》,第一个例子绘制了

1. 参数定义的House

2. a flurry of filled rectangles

3. Sierpinski曲线

含有鼠标和键盘响应函数onmouse和onkeyboard。

/************************************************************************/
/* CreateTime:2013-2-18
**Author:@Rachel Zhang
**Discription: Draw Parameter House, Flurry and Sierpinski
**3rd-party:OpenGL*/
/************************************************************************/

#include "GL/glut.h"
#include "stdlib.h"
#include
using namespace std;
#define screenHeight 480

class GLintPoint{
public:
?GLint x, y;
};

// Create a number between 0 and m(a number which will be given)
// the input m must be less than 32767 according to P49 in
int random(int m)
{
?return rand()%m;
}

void drawDot (GLint x, GLint y)
{
?glPointSize(3);
?glBegin(GL_POINTS);
?glVertex2i(x,y);
?glEnd();
}

typedef struct
{
?GLfloat r, g, b;
} GLfloatRGBColour;

GLfloatRGBColour colour[8] = { {0.0f, 0.0f, 0.0f}, {0.0f, 0.0f, 1.0f},
{0.0f, 1.0f, 0.0f}, {1.0f, 0.0f, 0.0f},
{0.0f, 1.0f, 1.0f}, {1.0f, 0.0f, 1.0f},
{1.0f, 1.0f, 0.0f}, {1.0f, 1.0f, 1.0f}};

void setPenColour(GLfloatRGBColour newColour)
{
?glColor3f(newColour.r, newColour.g, newColour.b);
}

/************************************************************************/
/*? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Draw Functions? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? */
/************************************************************************/
void parameterizedHouse(GLintPoint peak, GLint width, GLint height)
?// the top of house is at the peak; the size of house is given
?//? by height and width
{
?glBegin(GL_LINE_LOOP);
?glVertex2i(peak.x,? ? ? ? ? ? peak.y);? // draw shell of house
?glVertex2i(peak.x + width / 2, peak.y - 3 * height /8);
?glVertex2i(peak.x + width / 2,? peak.y -? ? height);
?glVertex2i(peak.x - width / 2, peak.y -? ? height);
?glVertex2i(peak.x - width / 2, peak.y - 3 * height /8);?
?glEnd();
}

void drawFlurry(int num, int Width, int Height)
?// draw num random rectangles in a Width by Height rectangle
{
?for (int i = 0; i < num; i++)
?{
? GLint x1 = random(Width);? ?// place corner randomly
? GLint y1 = random(Height);
? GLint x2 = random(Width); ? // pick the size so it fits
? GLint y2 = random(Height);
? GLfloat lev = random(10)/10.0;? // random value, in range 0 to 1
? glColor3f(lev,lev,lev);? ?// set the gray level
? glRecti(x1, y1, x2, y2);? ?// draw the rectangle
?}
?glFlush();
}?

void drawSierpinski(GLintPoint corner[3])
{
?int i, index, tcolour=0;
?GLintPoint point;
?point = corner[random(3)];
?drawDot(point.x, point.y);

?for (i = 0; i < 1000; i++)
?{
? index = random(3);
? point.x = (point.x + corner[index].x)/2;
? point.y = (point.y + corner[index].y)/2;?
? tcolour = (++tcolour)%7;? ? ? // col = (col + 1) mod 7;
? setPenColour(colour[tcolour]);
? drawDot(point.x, point.y);
?}
}

/************************************************************************/
/*? ? ? ? ? ? ? ? ? ? ? ? Mouse Listener and keyboard Listener? ? ? ? ? ? ? ? ? ? */
/************************************************************************/
void myMouse(int button, int state, int x, int y)
{
?static GLintPoint corners[3];
?static int numCorners;

?if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
?{
? corners[numCorners].x = x;
? corners[numCorners].y = screenHeight - y - 1;
? if (++numCorners == 3)
? {
? ?drawSierpinski(corners);
? ?numCorners = 0;
? }
?}
?else if (button==GLUT_RIGHT_BUTTON)
? glClear(GL_COLOR_BUFFER_BIT);
?glFlush();
}