Thanks that’s perfect!
I’m now trying to rotate the cube using the arrow keys using glRotatef() and i’ve got it working but it’s not working as I’d like. It’s quite hard to explain but I think the cube is rotating around the global Y axis and the normal X axis instead of rotating always rotating around the normal. Here’s my whole code if you don’t mind taking a look.
// CW1.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <windows.h> // Standard Header For Most Programs
#include <gl/gl.h> // The GL Header File
#include <glut.h> // The GL Utility Toolkit (Glut) Header
#include <math.h> // For mathematic operation
double rotate_y = 0;
double rotate_x = 0;
char Rendermode;
int _tmain(int argc, _TCHAR* argv[])
{
return 0;
}
void InitGL(GLvoid) // Create Some Everyday Functions for Initialization
{
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glEnable(GL_COLOR_MATERIAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity();
gluLookAt(1.5f, 2.0f, 5.0f,
0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f); //Set the point looking at
glRotatef(rotate_x, 1.0f, 0.0f, 0.0f); //X
glRotatef(rotate_y, 0.0f, 1.0f, 0.0f); //Y
switch (Rendermode) { //different render mode
case 'f': // for display faces
glBegin(GL_QUADS); //Draw a quad
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);
// Bottom face (y = -1.0f)
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 (z = 1.0f)
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);
// Back face (z = -1.0f)
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 face (x = -1.0f)
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);
// Right face (x = 1.0f)
glColor3f(1.0f, 0.0f, 1.0f); // Magenta
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();
break;
case 'v': // for display points
glBegin(GL_POINTS); // Draw points
glColor3f(0.0f, 1.0f, 0.0f); // Set The Color To 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);
glVertex3f(1.0f, -1.0f, -1.0f); //right side back bottom
glVertex3f(1.0f, 1.0f, -1.0f); //right side back top
glVertex3f(-1.0f, 1.0f, -1.0f); //left side back top
glVertex3f(-1.0f, -1.0f, -1.0f); //left side back bottom
glEnd(); // Done Drawing Points
glPointSize(5); //Set Points Size
break;
case 'e': // for display edges
glBegin(GL_LINES);
glColor3f(0.0f, 0.0f, 1.0f); // Set The Color To 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);
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);
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);
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);
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);
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(); // Done Drawing Edges
break;
}
// draw frame *************************************************************
//TO DO: Draw Cartesian scene coordinate system
// draw frame *************************************************************
glutSwapBuffers(); // Swap The Buffers To Not Be Left With A Clear Screen
}
void reshape(int width, int height) // Create The Reshape Function (the viewport)
{
if (height == 0) // Prevent A Divide By Zero By
{
height = 1; // Making Height Equal One
}
glViewport(0, 0, width, height); // Reset The Current Viewport
glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix
// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 100.0f);
glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity();
}
void keyboard(unsigned char key, int x, int y) // Create Keyboard Function
{
switch (key) {
case 27: // When Escape Is Pressed...
exit(0); // Exit The Program
break; // Ready For Next Case
case 'v': //Vetices Only
Rendermode = 'v';
break;
case 'e':
Rendermode = 'e';
break;
case 'f':
Rendermode = 'f';
break;
// Rotate the Cube*****************************************
// TO DO : Use some keys to rotate the cube.
// Rotate the Cube*****************************************
default: // Now Wrap It Up
break;
}
glutPostRedisplay(); //request display() call ASAP
}
//TO DO: using mouse click and move (or arrow keys) to rotate, zoom in/out and pan the camera*********************
void arrow_keys(int a_keys, int x, int y) // Create Special Function (required for arrow keys)
{
switch (a_keys) {
case GLUT_KEY_UP: // When Up Arrow Is Pressed...
rotate_x += -5;
break;
case GLUT_KEY_DOWN: // When Down Arrow Is Pressed...
rotate_x += 5;
break;
case GLUT_KEY_RIGHT: // When Right Arrow Is Pressed...
rotate_y += 5; // Rotate cube by +5 on the Y-Axis
break;
case GLUT_KEY_LEFT: // When Left Arrow Is Pressed...
rotate_y += -5; // Rotate cube by -5 on the Y-Axis
break;
default:
break;
}
}
void mouseButton(int button, int state, int x, int y) {
}
void mouseMove(int x, int y) {
}
//TO DO: using mouse click and move (or arrow keys) to rotate, zoom in/out and pan the camera*********************
void main(int argc, char** argv) // Create Main Function For Bringing It All Together
{
glutInit(&argc, argv); // Erm Just Write It =)
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE); // Display Mode
glutInitWindowSize(500, 500); // If glutFullScreen wasn't called this is the window size
glutCreateWindow("CW1 OpenGL Framework"); // Window Title (argv[0] for current directory as title)
glutFullScreen(); // Put Into Full Screen
InitGL();
Rendermode = 'f';
glutDisplayFunc(display); // Matching Earlier Functions To Their Counterparts
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard); //Keybord call back function.
glutSpecialFunc(arrow_keys);// Special key call back function.
glutMouseFunc(mouseButton); // mouse click call back function.
glutMotionFunc(mouseMove); //mouse move call back function.
glutIdleFunc(display);
glutMainLoop(); // Initialize The Main Loop
}