Hi there,
I have the following code and when ran a cube is shown and using the mouse and holding the left mouse button you can rotate it. The problem is that you can rotate the cube whether you click on the cube or the background.
What i would like to do is rotate the cube only when the mouse pointer is clicked onto the cube. Reading up i have read that i would need to implement picking/selection techniques.
Can anyone help me as i am haveing some trouble? I would then like to be able to move(drag) the cube with the mouse around the screen.
Kind Regards
Nick
#include <gl/glut.h>
bool fullscreen = false;
bool mouseDown = false;
float xrot = 0.0f;
float yrot = 0.0f;
float xdiff = 0.0f;
float ydiff = 0.0f;
void drawBox()
{
glBegin(GL_QUADS);
glColor3f(1.0f, 0.0f, 0.0f);
// FRONT
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f( 0.5f, -0.5f, 0.5f);
glVertex3f( 0.5f, 0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, 0.5f);
// BACK
glVertex3f(-0.5f, -0.5f, -0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glVertex3f( 0.5f, 0.5f, -0.5f);
glVertex3f( 0.5f, -0.5f, -0.5f);
glColor3f(0.0f, 1.0f, 0.0f);
// LEFT
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, 0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
glVertex3f(-0.5f, -0.5f, -0.5f);
// RIGHT
glVertex3f( 0.5f, -0.5f, -0.5f);
glVertex3f( 0.5f, 0.5f, -0.5f);
glVertex3f( 0.5f, 0.5f, 0.5f);
glVertex3f( 0.5f, -0.5f, 0.5f);
glColor3f(0.0f, 0.0f, 1.0f);
// TOP
glVertex3f(-0.5f, 0.5f, 0.5f);
glVertex3f( 0.5f, 0.5f, 0.5f);
glVertex3f( 0.5f, 0.5f, -0.5f);
glVertex3f(-0.5f, 0.5f, -0.5f);
// BOTTOM
glVertex3f(-0.5f, -0.5f, 0.5f);
glVertex3f(-0.5f, -0.5f, -0.5f);
glVertex3f( 0.5f, -0.5f, -0.5f);
glVertex3f( 0.5f, -0.5f, 0.5f);
glEnd();
}
bool init()
{
glClearColor(0.93f, 0.93f, 0.93f, 0.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glClearDepth(1.0f);
return true;
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt(
0.0f, 0.0f, 3.0f,
0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f);
glRotatef(xrot, 1.0f, 0.0f, 0.0f);
glRotatef(yrot, 0.0f, 1.0f, 0.0f);
drawBox();
glFlush();
glutSwapBuffers();
}
void resize(int w, int h)
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(0, 0, w, h);
gluPerspective(45.0f, 1.0f * w / h, 1.0f, 100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void idle()
{
if (!mouseDown)
{
xrot += 0.3f;
yrot += 0.4f;
}
glutPostRedisplay();
}
void keyboard(unsigned char key, int x, int y)
{
switch(key)
{
case 27 :
exit(1); break;
}
}
void specialKeyboard(int key, int x, int y)
{
if (key == GLUT_KEY_F1)
{
fullscreen = !fullscreen;
if (fullscreen)
glutFullScreen();
else
{
glutReshapeWindow(500, 500);
glutPositionWindow(50, 50);
}
}
}
void mouse(int button, int state, int x, int y)
{
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
{
mouseDown = true;
xdiff = x - yrot;
ydiff = -y + xrot;
}
else
mouseDown = false;
}
void mouseMotion(int x, int y)
{
if (mouseDown)
{
yrot = x - xdiff;
xrot = y + ydiff;
glutPostRedisplay();
}
}
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowPosition(50, 50);
glutInitWindowSize(500, 500);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutCreateWindow("13 - Solid Shapes");
glutDisplayFunc(display);
glutKeyboardFunc(keyboard);
glutSpecialFunc(specialKeyboard);
glutMouseFunc(mouse);
glutMotionFunc(mouseMotion);
glutReshapeFunc(resize);
//glutIdleFunc(idle);
if (!init())
return 1;
glutMainLoop();
return 0;
}