Noções básicas de visão computacional (desenho, linhas retas, retângulos, translação, rotação, dimensionamento, etc.)

O principal é usar alguns dos princípios mais básicos para desenhar linhas retas, retângulos, etc. Os algoritmos mais básicos são o algoritmo DDA e o algoritmo de Bresenham.

1. Rato interativo

#include <GL/glut.h>

GLint w=600,h=500;
GLint dx=0,dy=0;

void myDisplay()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(0.5,0.6,0.7);
    glPointSize(5);
    glBegin(GL_POLYGON);
    glVertex2i(100+dx,100+dy);
    glVertex2i(100+dx,500+dy);
    glVertex2i(300+dx,250+dy);
    glEnd();
    glFlush();
}


void mouseMotion(GLint button, GLint state, GLint x,GLint y)
{
    if(button==GLUT_LEFT_BUTTON && state == GLUT_DOWN)
    {
        dx=x;
        dy=h-y;
        glutPostRedisplay();
    }

}


void init()
{
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0,w,0,h);
}



int main(int argc, char* argv[])
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);
    glutInitWindowPosition(200,300);
    glutInitWindowSize(w,h);
    glutCreateWindow("鼠º¨®标À¨º绘?制?");
    
    init();
    glutDisplayFunc(myDisplay);
    glutMouseFunc(mouseMotion);
    glutMainLoop();
    return 0;
}

1. Desenho de imagem interativa do teclado

#include <GL/glut.h>


int xd=0,yd=0;
void myDisplay()
{

    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(0.5,0.6,0.7);
    glPointSize(5);
    glBegin(GL_POLYGON);
    glVertex2i(10+xd,10+yd);
    glVertex2i(20+xd,40+yd);
    glVertex2i(50+xd,60+yd);
    glEnd();
    glFlush();
}

void myKeyBorad(unsigned char key,int x,int y)
{
    switch(key)
    {
    case 'w':yd++; break;
    case 's':yd--; break;
    case 'a':xd--; break;
    case 'd':xd++; break;
    }
    glutPostRedisplay();
}


void init()
{
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(-100,100,-100,100);
}
    

int main(int argc, char* argv[])
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);
    glutInitWindowPosition(200,300);
    glutInitWindowSize(300,300);
    glutCreateWindow("鼠º¨®标À¨º绘?制?");
    
    init();
    glutDisplayFunc(myDisplay);
    glutKeyboardFunc(myKeyBorad);
    glutMainLoop();
    return 0;
}

2. Baseado no algoritmo DDA

#include <GL/glut.h>
#include<math.h>

void mydisplay()
{
    
    glClear(GL_COLOR_BUFFER_BIT);
    glPointSize(3);
    

    glBegin(GL_LINES);
    glColor3f(0.3,0.1,0.8);
    glVertex2i(-100,10);
    glVertex2i(100,10);
    glEnd();
    
    glBegin(GL_LINES);
    glColor3f(0.3,0.1,0.8);
    glVertex2i(0,-100);
    glVertex2i(0,100);
    glEnd();//建¡§立¢¡é坐Á?标À¨º系¦Ì

    //glBegin(GL_POINTS);//点Ì?的Ì?绘?制?
    //glBegin(GL_LINE_STRIP);//线?段?绘?制?
    //glBegin(GL_LINES);
    //glBegin(GL_LINE_LOOP);//多¨¤边À?形?绘?制?
    //glBegin(GL_POLYGON);//多¨¤边À?形?绘?制?填¬?充?
    //glBegin(GL_TRIANGLES);//三¨y角?形?绘?制?填¬?充?
    //glBegin(GL_QUADS);//绘?制?四?边À?形?


    glBegin(GL_POLYGON);//填¬?充?的Ì?四?边À?形?
    glColor3f(3.0,2.1,0.8);
    glVertex2i(10,10);
    glVertex2i(50,10);
    glVertex2i(50,40);
    glVertex2i(10,40);
    glEnd();

    //glTranslatef(-50,-50,0);//平?移°?
    //glRotatef(30,0,0,1);//旋y转Áa
    glScalef(2,2,1);//缩?放¤?

    glBegin(GL_POLYGON);//填¬?充?的Ì?四?边À?形?
    glColor3f(0.8,0.6,0.5);
    glVertex2i(10,10);
    glVertex2i(50,10);
    glVertex2i(50,40);
    glVertex2i(10,40);
    glEnd();



    glFlush();
};



void init()
{
    glClearColor(1.0, 1.0, 1.0, 0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(-100,100,-100,100);

};

int main(int argc, char* argv[])
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB|GLUT_SINGLE);
    glutInitWindowPosition(300,300);
    glutInitWindowSize(600,500);
    glutCreateWindow("二t维?变À?换?");
    
    init();
    glutDisplayFunc(mydisplay);
    glutMainLoop();
};

Os efeitos mostram translação, dimensionamento, rotação, etc.