Moving 3d shapes with keyboard in OpenGL with C++ - c++

Question

I'm trying to move the pyramid and cubic "separately" to front-back , up-down and right-left using arrows and page-up, page-down keys but I couldn't make it yet , none of the tow shape are moving my 2 questions are : how can i chose witch one of these shapes i want to move , and why none of them are moving ?
Thanks.
#include <GL/glut.h>
float xmove = 0, ymove = 0, zmove = 0;
float degree = 0;
float xscale = 1, yscale = 1, zscale = 1;
void right(void)
{
glLoadIdentity();//koordinat sistemimizetkilenmesin
xmove += 0.1;
}
void left(void)
{
glLoadIdentity();
xmove -= 0.1;
}
void up(void)
{
glLoadIdentity();
ymove += 0.1;
}
void down(void)
{
glLoadIdentity();
ymove -= 0.1;
}
void front(void)
{
glLoadIdentity();
zmove -= 0.1;
}
void back(void)
{
glLoadIdentity();
zmove += 0.1;
}
void keyboard(int button, int x, int y)
{
switch (button)
{
case GLUT_KEY_LEFT:left(); break;
case GLUT_KEY_RIGHT:right(); break;
case GLUT_KEY_UP:up(); break;
case GLUT_KEY_DOWN:down(); break;
case GLUT_KEY_PAGE_UP:front(); break;
case GLUT_KEY_PAGE_DOWN:back(); break;
glutPostRedisplay();
}
}
void Settings()
{
glClearColor(1,1,1,0);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glShadeModel(GL_SMOOTH);
glHint(GL_PERSPECTIVE_CORRECTION_HINT , GL_NICEST);
}
void polygons(void)
{
glColor3f(1.0, 0.0, 0.0);
glRotatef(degree, 0.0, 1.0, 0.0);
glScalef(xscale, yscale, zscale);
glTranslatef(1.5, 0.0, -8.0);
glBegin(GL_TRIANGLES);//pyramid
// fronat face
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(-1.0f, -1.0f, 1.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(1.0f, -1.0f, 1.0f);
// down face
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(1.0f, -1.0f, 1.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(1.0f, -1.0f, -1.0f);
//back
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(1.0f, -1.0f, -1.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(-1.0f, -1.0f, -1.0f);
//left
glColor3f(1.0f, 0.0f, 0.0f); //reed
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(-1.0f, -1.0f, -1.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(-1.0f, -1.0f, 1.0f);
glEnd();
glLoadIdentity();
glTranslatef(-1.5, 0.0, -8.0);
glBegin(GL_QUADS); //cubic
glColor3f(1.0f, 0.0f, 1.0f); //pink
glVertex3f(1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
//down face
glColor3f(1.0f, 0.5f, 0.0f); //orange
glVertex3f(1.0f, -1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
//front face
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
//back
glColor3f(1.0f, 1.0f, 0.0f); //yellow
glVertex3f(1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(1.0f, 1.0f, -1.0f);
//left
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
//right
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(1.0f, 1.0f, -1.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
glEnd();
}
void DrawingFunction()//painting
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
gluLookAt(0.0, 0.0, 2.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
polygons();
glutSwapBuffers();
}
void AppearanceAdjustment(int x, int y)
{
int aspect = x / y;
glViewport(0, 0, x, y);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45,aspect,0.1,20);
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE);
glutInitWindowPosition(50, 50);
glutInitWindowSize(800, 600);
glutCreateWindow("3d shapes");
glutDisplayFunc(DrawingFunction);
glutReshapeFunc(AppearanceAdjustment);
glutSpecialFunc(keyboard);
Settings();
glutMainLoop();
return 0;
}

Answer 1

glLoadIdentity() has to be called in DrawingFunction:
void DrawingFunction()//painting
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity(); // <----
gluLookAt(0.0, 0.0, 2.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
polygons();
glutSwapBuffers();
}
Add an array of offsets and an object number:
int object = 0;
float xmove[]{ 0, 0 };
float ymove[]{ 0, 0 };
float zmove[]{ 0, 0 };
Add object selection buttons and change the offset of the selected object.
glutPostRedisplay() has to be executed after the switch statement:
void keyboard(int button, int x, int y)
{
switch (button)
{
case GLUT_KEY_F1: object = 0; break;
case GLUT_KEY_F2: object = 1; break;
case GLUT_KEY_LEFT: xmove[object] -= 0.1; break;
case GLUT_KEY_RIGHT: xmove[object] += 0.1; break;
case GLUT_KEY_DOWN: ymove[object] -= 0.1; break;
case GLUT_KEY_UP: ymove[object] += 0.1; break;
case GLUT_KEY_PAGE_UP: zmove[object] -= 0.1; break;
case GLUT_KEY_PAGE_DOWN: zmove[object] += 0.1; break;
}
glutPostRedisplay();
}
You have to translate the objects object by glTranslatef(xmove[i], ymove[i], zmove[i]). I recommend to use glPushMatrix/glPopMatrix:
void polygons(void)
{
glPushMatrix();
glColor3f(1.0, 0.0, 0.0);
glRotatef(degree, 0.0, 1.0, 0.0);
glScalef(xscale, yscale, zscale);
glTranslatef(1.5, 0.0, -8.0);
glTranslatef(xmove[0], ymove[0], zmove[0]); // <--- translate pyramid
// draw pyramid
glBegin(GL_TRIANGLES);//pyramid
// [...]
glEnd();
glTranslatef(-1.5, 0.0, -8.0);
glTranslatef(xmove[1], ymove[1], zmove[1]); // <--- translate cube
glBegin(GL_QUADS); //cubic
// [...]
glEnd();
glPopMatrix();
}
Example code:
int object = 0;
float xmove[]{ 0, 0 };
float ymove[]{ 0, 0 };
float zmove[]{ 0, 0 };
float degree = 0;
float xscale = 1, yscale = 1, zscale = 1;
void keyboard(int button, int x, int y)
{
switch (button)
{
case GLUT_KEY_F1: object = 0; break;
case GLUT_KEY_F2: object = 1; break;
case GLUT_KEY_LEFT: xmove[object] -= 0.1; break;
case GLUT_KEY_RIGHT: xmove[object] += 0.1; break;
case GLUT_KEY_DOWN: ymove[object] -= 0.1; break;
case GLUT_KEY_UP: ymove[object] += 0.1; break;
case GLUT_KEY_PAGE_UP: zmove[object] -= 0.1; break;
case GLUT_KEY_PAGE_DOWN: zmove[object] += 0.1; break;
}
glutPostRedisplay();
}
void Settings()
{
glClearColor(1,1,1,0);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glShadeModel(GL_SMOOTH);
glHint(GL_PERSPECTIVE_CORRECTION_HINT , GL_NICEST);
}
void polygons(void)
{
glPushMatrix();
glColor3f(1.0, 0.0, 0.0);
glRotatef(degree, 0.0, 1.0, 0.0);
glScalef(xscale, yscale, zscale);
glTranslatef(1.5, 0.0, -8.0);
glTranslatef(xmove[0], ymove[0], zmove[0]); // <--- translate pyramid
glBegin(GL_TRIANGLES);//pyramid
// fronat face
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(-1.0f, -1.0f, 1.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(1.0f, -1.0f, 1.0f);
// down face
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(1.0f, -1.0f, 1.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(1.0f, -1.0f, -1.0f);
//back
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(1.0f, -1.0f, -1.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(-1.0f, -1.0f, -1.0f);
//left
glColor3f(1.0f, 0.0f, 0.0f); //reed
glVertex3f(0.0f, 1.0f, 0.0f);
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(-1.0f, -1.0f, -1.0f);
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(-1.0f, -1.0f, 1.0f);
glEnd();
glPopMatrix();
glPushMatrix();
glTranslatef(-1.5, 0.0, -8.0);
glTranslatef(xmove[1], ymove[1], zmove[1]); // <--- translate cube
glBegin(GL_QUADS); //cubic
glColor3f(1.0f, 0.0f, 1.0f); //pink
glVertex3f(1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
//down face
glColor3f(1.0f, 0.5f, 0.0f); //orange
glVertex3f(1.0f, -1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
//front face
glColor3f(0.0f, 0.0f, 1.0f); //blue
glVertex3f(1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
//back
glColor3f(1.0f, 1.0f, 0.0f); //yellow
glVertex3f(1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(1.0f, 1.0f, -1.0f);
//left
glColor3f(1.0f, 0.0f, 0.0f); //red
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
//right
glColor3f(0.0f, 1.0f, 0.0f); //green
glVertex3f(1.0f, 1.0f, -1.0f);
glVertex3f(1.0f, 1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, 1.0f);
glVertex3f(1.0f, -1.0f, -1.0f);
glEnd();
glPopMatrix();
}
void DrawingFunction()//painting
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0.0, 0.0, 2.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
polygons();
glutSwapBuffers();
}
void AppearanceAdjustment(int x, int y)
{
int aspect = x / y;
glViewport(0, 0, x, y);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45,aspect,0.1,20);
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE);
glutInitWindowPosition(50, 50);
glutInitWindowSize(800, 600);
glutCreateWindow("3d shapes");
glutDisplayFunc(DrawingFunction);
glutReshapeFunc(AppearanceAdjustment);
glutSpecialFunc(keyboard);
Settings();
glutMainLoop();
return 0;
}

Answer 2

You need to use a key press to pick one of the shapes similar to how you trigger the up, down, left, right ... Etc functions. Say press a for the first shape then set a global int ishape= 1 or ishape=2 if b is pressed. The draw function will then check the value of ishape to see which shape it should move. But really you need a vector of move for each shape else their displacements will be mixed up.Then you need to apply gltranslate on the shape that needs to be displaced using the move vector.