[OpenGL]課後案例06：畫圖程式

//A.6  畫圖程式/* 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 resizedor 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();}