[OpenGL]课后案例06：画图程序-优快云博客

//A.6  画图程序
/* simple painting program with text, lines, triangles,
rectangles,and points */
#define NULL 0
#define LINE 1
#define RECTANGLE 2
#define TRIANGLE  3
#define POINTS 4
#define TEXT 5
#include <stdlib.h>
#include <GL/glut.h>
void mouse(int, int, int, int);
void key(unsigned char, int, int);
void display(void);
void drawSquare(int, int);
void myReshape(GLsizei, GLsizei);
void myinit(void);
void screen_box(int, int, int);
void right_menu(int);
void middle_menu(int);
void color_menu(int);
void pixel_menu(int);
void fill_menu(int);
int pick(int, int);
/* globals */
GLsizei wh = 500, ww = 500; /* initial window size */
GLfloat size = 3.0;   /* half side length of square */
int draw_mode = 0; /* drawing mode */
int rx, ry; /* raster position */
GLfloat r = 1.0, g = 1.0, b = 1.0; /* drawing color */
int fill = 0; /* fill flag */
void drawSquare(int x, int y)
{
    y=wh-y;
    glColor3ub( (char) rand()%256, (char) rand()%256, (char) rand()
        %256);
    glBegin(GL_POLYGON);
    glVertex2f(x+size, y+size);
    glVertex2f(x-size, y+size);
    glVertex2f(x-size, y-size);
    glVertex2f(x+size, y-size);
    glEnd();
}
/* rehaping routine called whenever window is resized
or moved */
void myReshape(GLsizei w, GLsizei h)
{
    /* adjust clipping box */
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    /* adjust viewport and  clear */
    glViewport(0,0,w,h);
    glClearColor (0.8, 0.8, 0.8, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    display();
    glFlush();
    /* set global size for use by drawing routine */
    ww = w;
    wh = h;
}
void myinit(void)
{
    glViewport(0,0,ww,wh);
    /* Pick 2D clipping window to match size of X window.
    This choice avoids having to scale object coordinates
    each time window is resized.*/
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, (GLdouble) ww , 0.0, (GLdouble) wh , -1.0, 1.0);
    /* set clear color to black and clear window */
    glClearColor (0.8, 0.8, 0.8, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glFlush();
}
void mouse(int btn, int state, int x, int y)
{
    static int count;
    int where;
    static int xp[2],yp[2];
    if(btn==GLUT_LEFT_BUTTON && state==GLUT_DOWN)
    {
        glPushAttrib(GL_ALL_ATTRIB_BITS);
        where = pick(x,y);
        glColor3f(r, g, b);
        if(where != 0)
        {
            count = 0;
            draw_mode = where;
        }
        else switch(draw_mode)
        {
        case(LINE):
            if(count==0)
            {
                count++;
                xp[0] = x;
                yp[0] = y;
            }
            else
            {
                glBegin(GL_LINES);
                glVertex2i(x,wh-y);
                glVertex2i(xp[0],wh-yp[0]);
                glEnd();
                draw_mode=0;
                count=0;
            }
            break;
        case(RECTANGLE):
            if(count == 0)
            {
                count++;
                xp[0] = x;
                yp[0] = y;
            }
            else
            {
                if(fill) glBegin(GL_POLYGON);
                else glBegin(GL_LINE_LOOP);
                glVertex2i(x,wh-y);
                glVertex2i(x,wh-yp[0]);
                glVertex2i(xp[0],wh-yp[0]);
                glVertex2i(xp[0],wh-y);
                glEnd();
                draw_mode=0;
                count=0;
            }
            break;
        case (TRIANGLE):
            switch(count)
            {
            case(0):
                count++;
                xp[0] = x;
                yp[0] = y;
                break;
            case(1):
                count++;
                xp[1] = x;
                yp[1] = y;
                break;
            case(2):
                if(fill) glBegin(GL_POLYGON);
                else glBegin(GL_LINE_LOOP);
                glVertex2i(xp[0],wh-yp[0]);
                glVertex2i(xp[1],wh-yp[1]);
                glVertex2i(x,wh-y);
                glEnd();
                draw_mode=0;
                count=0;
            }
            break;
        case(POINTS):
            {
                drawSquare(x,y);
                count++;
            }
            break;
        case(TEXT):
            {
                rx=x;
                ry=wh-y;
                glRasterPos2i(rx,ry);  
                count=0;
            }
        }
        glPopAttrib();
        glFlush();
    }
}
int pick(int x, int y)
{
    y = wh - y;
    if(y < wh-ww/10) return 0;
    else if(x < ww/10) return LINE;
    else if(x < ww/5) return RECTANGLE;
    else if(x < 3*ww/10) return TRIANGLE;
    else if(x < 2*ww/5) return POINTS;
    else if(x < ww/2) return TEXT;
    else return 0;
}
void screen_box(int x, int y, int s )
{
    glBegin(GL_QUADS);
    glVertex2i(x, y);
    glVertex2i(x+s, y);
    glVertex2i(x+s, y+s);
    glVertex2i(x, y+s);
    glEnd();
}
void right_menu(int id)
{
    if(id == 1) exit(0);
    else display();
}
void middle_menu(int id)
{
}
void color_menu(int id)
{
    if(id == 1) {r = 1.0; g = 0.0; b = 0.0;}
    else if(id == 2) {r = 0.0; g = 1.0; b = 0.0;}
    else if(id == 3) {r = 0.0; g = 0.0; b = 1.0;}
    else if(id == 4) {r = 0.0; g = 1.0; b = 1.0;}
    else if(id == 5) {r = 1.0; g = 0.0; b = 1.0;}
    else if(id == 6) {r = 1.0; g = 1.0; b = 0.0;}
    else if(id == 7) {r = 1.0; g = 1.0; b = 1.0;}
    else if(id == 8) {r = 0.0; g = 0.0; b = 0.0;}
}
void pixel_menu(int id)
{
    if (id == 1) size = 2 * size;
    else if (size > 1) size = size/2;
}
void fill_menu(int id)
{
    if (id == 1) fill = 1;
    else fill = 0;
}
void key(unsigned char k, int xx, int yy)
{
    if(draw_mode!=TEXT) return;
    glColor3f(0.0,0.0,0.0);
    glRasterPos2i(rx,ry);
    glutBitmapCharacter(GLUT_BITMAP_9_BY_15, k);
    /* glutStrokeCharacter(GLUT_STROKE_ROMAN,i); */
    rx+=glutBitmapWidth(GLUT_BITMAP_9_BY_15,k);
}
void display(void)
{
    int shift=0;
    glPushAttrib(GL_ALL_ATTRIB_BITS);
    glClearColor (0.8, 0.8, 0.8, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0, 1.0, 1.0);
    screen_box(0,wh-ww/10,ww/10);
    glColor3f(1.0, 0.0, 0.0);
    screen_box(ww/10,wh-ww/10,ww/10);
    glColor3f(0.0, 1.0, 0.0);
    screen_box(ww/5,wh-ww/10,ww/10);
    glColor3f(0.0, 0.0, 1.0);
    screen_box(3*ww/10,wh-ww/10,ww/10);
    glColor3f(1.0, 1.0, 0.0);
    screen_box(2*ww/5,wh-ww/10,ww/10);
    glColor3f(0.0, 0.0, 0.0);
    screen_box(ww/10+ww/40,wh-ww/10+ww/40,ww/20);
    glBegin(GL_LINES);
    glVertex2i(wh/40,wh-ww/20);
    glVertex2i(wh/40+ww/20,wh-ww/20);
    glEnd();

    glBegin(GL_TRIANGLES);
    glVertex2i(ww/5+ww/40,wh-ww/10+ww/40);
    glVertex2i(ww/5+ww/20,wh-ww/40);
    glVertex2i(ww/5+3*ww/40,wh-ww/10+ww/40);
    glEnd();
    glPointSize(3.0);
    glBegin(GL_POINTS);
    glVertex2i(3*ww/10+ww/20, wh-ww/20);
    glEnd();
    glRasterPos2i(2*ww/5,wh-ww/20);
    glutBitmapCharacter(GLUT_BITMAP_9_BY_15, 'A');
    shift=glutBitmapWidth(GLUT_BITMAP_9_BY_15, 'A');
    glRasterPos2i(2*ww/5+shift,wh-ww/20);
    glutBitmapCharacter(GLUT_BITMAP_9_BY_15, 'B');
    shift+=glutBitmapWidth(GLUT_BITMAP_9_BY_15, 'B');
    glRasterPos2i(2*ww/5+shift,wh-ww/20);

    glutBitmapCharacter(GLUT_BITMAP_9_BY_15, 'C');
    glFlush();
    glPopAttrib();
}
int main(int argc, char** argv)
{
    int c_menu, p_menu, f_menu;
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutCreateWindow("square");
    glutDisplayFunc(display);
    c_menu = glutCreateMenu(color_menu);
    glutAddMenuEntry("Red",1);
    glutAddMenuEntry("Green",2);
    glutAddMenuEntry("Blue",3);
    glutAddMenuEntry("Cyan",4);
    glutAddMenuEntry("Magenta",5);
    glutAddMenuEntry("Yellow",6);
    glutAddMenuEntry("White",7);
    glutAddMenuEntry("Black",8);
    p_menu = glutCreateMenu(pixel_menu);
    glutAddMenuEntry("increase pixel size", 1);
    glutAddMenuEntry("decrease pixel size", 2);
    f_menu = glutCreateMenu(fill_menu);
    glutAddMenuEntry("fill on", 1);
    glutAddMenuEntry("fill off", 2);
    glutCreateMenu(right_menu);
    glutAddMenuEntry("quit",1);
    glutAddMenuEntry("clear",2);
    glutAttachMenu(GLUT_RIGHT_BUTTON);
    glutCreateMenu(middle_menu);
    glutAddSubMenu("Colors", c_menu);
    glutAddSubMenu("Pixel Size", p_menu);
    glutAddSubMenu("Fill", f_menu);
    glutAttachMenu(GLUT_MIDDLE_BUTTON);
    myinit ();
    glutReshapeFunc (myReshape);
    glutKeyboardFunc(key);
    glutMouseFunc (mouse);
    glutMainLoop();
}