Hi,
i recently implemented a trackball and it is nice to visualize any object.
Now i am trying to plot 3d points in space. when the application starts I can plot and visualize my points in the screen (640 x 480), but when I rotate the modelview matrix and plot new points they remain being render in the same place.
my problem (i guess) is to find a way to setup the Z coordinate of my 3d point to it can be ploted on the right place.
i let the main code and auxiliary below:
main file:
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#include <math.h>
#include <stdlib.h>
#include "Point.h"
#include <vector>
GLfloat mouseX_, mouseY_; //posicao inicial do cursor
bool rotationing = true;
GLfloat matrix [] = {1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1};
std::vector<Point> points;
bool mousePlot = true;
void display(void)
{
/* display callback, clear frame buffer and z buffer,
plot points and draw references, swap buffers */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glutWireTeapot(100);
for(int i = 0; i < points.size(); i++){
glBegin(GL_POINTS);
glColor3f(1.0,0.0,0.1);
glPointSize(100);
glVertex3f(points.at(i).x, points.at(i).y, points.at(i).z);
glEnd();
}
glFlush();
glutSwapBuffers();
}
void mouse(int btn, int state, int x, int y)
{
if(btn == GLUT_LEFT_BUTTON && mousePlot){
float x_ = (float) x - glutGet(GLUT_WINDOW_WIDTH)/2;
float y_ = (float) -(y - glutGet(GLUT_WINDOW_HEIGHT)/2);
float z = 0.0;
Point *p = new Point(x_,y_,z);
points.push_back(*p);
}
if(btn == GLUT_RIGHT_BUTTON){
mousePlot = !mousePlot;
}
}
void myReshape(int w, int h)
{
float nRange = w/2;
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-w/2, w/2, -h/2, h/2, -nRange, nRange);
glMatrixMode(GL_MODELVIEW);
}
void trackball(int PX, int PY){
//mouse = anterior position
//P = position in use
if (rotationing && !mousePlot){
GLint W = glutGet(GLUT_WINDOW_WIDTH);
GLint H = glutGet(GLUT_WINDOW_HEIGHT);
GLfloat ray; //for while, i needn't take the sqrt for the ray.
if (W>H) ray=W*W/2;
else ray=H*H/2;
mouseX_ -= W/2; //
GLfloat px = PX - W/2; // this part is to use the center
mouseY_ = H/2 - mouseY_; // of the screen as the origin
GLfloat py = H/2 - PY; //
//the idea is to find the Z coordinate of the two points in sphere's surface centered in the origin
GLfloat mouseX_Y2 = mouseX_*mouseX_ + mouseY_*mouseY_;
GLfloat pXY2 = px*px+py*py;
if (mouseX_Y2 < ray && pXY2 < ray){ //this trackball only works for points inside the sphere
GLfloat mouseZ = sqrt(ray - mouseX_Y2);
GLfloat pz = sqrt(ray - pXY2);
GLfloat axisRotation[3]; //vector product "mouse X P"
axisRotation[0] = -mouseZ*py + mouseY_*pz;
axisRotation[1] = mouseZ*px - mouseX_*pz;
axisRotation[2] = -mouseY_*px + mouseX_*py;
GLfloat anguloRotacao = atan(sqrt(axisRotation[0]*axisRotation[0] + axisRotation[1]*axisRotation[1] + axisRotation[2]*axisRotation[2]));
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glRotatef(anguloRotacao,axisRotation[0],axisRotation[1],axisRotation[2]);
glMultMatrixf(matrix);
glGetFloatv(GL_MODELVIEW_MATRIX, matrix);
}
}
mouseX_ = PX;
mouseY_ = PY;
glutPostRedisplay();
}
void main(int argc, char **argv)
{
glutInit(&argc, argv);
/* need both double buffering and z buffer */
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(640, 480);
glutCreateWindow("draw :)");
glutReshapeFunc(myReshape);
glutDisplayFunc(display);
glutMouseFunc(mouse);
glutMotionFunc(trackball);
glEnable(GL_DEPTH_TEST); /* Enable hidden--surface--removal */
glutMainLoop();
}
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point.h:
#ifndef POINT_H
#define POINT_H
#include <iostream>
#include <OpenGL/gl/glut.h>
class Point {
public:
Point(void);
Point(float &x, float &y, float &z);
~Point(){
this->x = 0.0;
this->y = 0.0;
this->z = 0.0;
}
Point &getPoint(){ return *this;}
void setPoint(float &x, float &y, float &z);
void setPoint(float x, float y, float z);
void coordinates();
public:
float x, y, z;
};
#endif
point.cpp
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#include "Point.h";
Point::Point(void)
{
}
Point::Point(float &x, float &y, float &z)
{
this-> x = x;
this-> y = y;
this-> z = z;
}
void Point::setPoint(float &x, float &y, float &z)
{
this-> x = x;
this-> y = y;
this-> z = z;
}
void Point::setPoint(float x, float y, float z)
{
this-> x = x;
this-> y = y;
this-> z = z;
}
void Point::coordinates()
{
std::cout << "x = " << this->x;
std::cout << "y = " << this->y;
std::cout << "z = " << this->z;
}
