newpaint.c

计算机图形学～想必是很多人需要的～在此共享一下

/* newpaint.c   */

/* E. Angel, Interactive Computer Graphics */
/* A Top-Down Approach with OpenGL, Third Edition */
/* Addison-Wesley Longman, 2003 */


/* paint program from chapter 3  */

/* This program illustrates the use of the glut library for
interfacing with a window system */


#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();

}