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#include <stdio.h>#include <stdlib.h>#include <math.h>#include <GL/glut.h>#include "ppm_canvas.h"// globalsint width, height;float last_x, last_y;int paint_state;canvas_t canvas;// display callback functionvoid cb_display(void) {	// Do nothing	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	glColor3f(1.0, 1.0, 1.0);	glMatrixMode(GL_MODELVIEW);	glLoadIdentity();	glTranslatef(10,5, 0);	glBegin(GL_POLYGON);		glVertex2f(0.0, 0.0);		glVertex2f(0.0, 1.0);		glVertex2f(1.0, 1.0);	glEnd();	glFlush();}void cb_mouse(int button, int state, int x, int y) {	if(button == GLUT_LEFT_BUTTON)		switch(state){			case GLUT_DOWN: {				printf("CLICKDOWN(%d, %d)\n", x, y);			}break;		}}void cb_motion(int x, int y) {	}void cb_keyboard(unsigned char key, int x, int y) {	switch (key) {		case 'q':			exit(0);			break;		case 'c': {			glClear(GL_COLOR_BUFFER_BIT);			glClearColor(0, 0, 0, 0);			glFlush();		}break;	} // end switch}void cb_reshape(int w, int h) {	width = w;	height = h;		glViewport(0, 0, w, h);	glMatrixMode(GL_PROJECTION);	glLoadIdentity();	gluOrtho2D(0, w, 0, h);	glMatrixMode(GL_MODELVIEW);	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	glFlush();}int main(int argc, char **argv) {	glutInit(&argc, argv);	if(argc == 2) {		if(ppmLoadCanvas(argv[1], &canvas) < 0) {			printf("Failed to open: %s!\n", argv[1]);			exit(-1);		}		else printf("Loaded: %s\n", argv[1]);			}	else {		printf("Usage: Lab1 input\n");		exit(-1);	}	height = canvas.height;	width = canvas.width;	printf("Height = %d Width = %d\n", canvas.height, canvas.width);	glutInitWindowSize(height, width);	glutInitDisplayMode(GLUT_DEPTH | GLUT_RGBA);	glutCreateWindow("Paint My Wagon");	glEnable(GL_DEPTH_TEST);	glDepthFunc(GL_LEQUAL);	glEnable(GL_BLEND);	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);	glClearColor(0,0,0,0);		glutDisplayFunc(cb_display); 	glutMouseFunc(cb_mouse);	glutMotionFunc(cb_motion);	glutKeyboardFunc(cb_keyboard);	glutReshapeFunc(cb_reshape);	glutMainLoop();	return 0;}