// Points.c
// OpenGL SuperBible
// Demonstrates OpenGL Primative GL_POINTS
// Program by Richard S. Wright Jr.
#include "../../shared/gltools.h" // OpenGL toolkit
#include <math.h>
#include <cstdio>
// Define a constant for the value of PI
#define GL_PI 3.1415f
// Rotation amounts
static GLfloat xRot = 0.0f;
static GLfloat yRot = 0.0f;
// Called to draw scene
void RenderScene(void)
{
GLfloat x,y,z,angle; // Storeage for coordinat
// Save matrix state and do the rotation
glPushMatrix();
glRotatef(xRot, 1.0f, 0.0f, 0.0f);
glRotatef(yRot, 0.0f, 1.0f, 0.0f);
// Call only once for all remaining points
glBegin(GL_POINTS);
z = -50.0f;
for(angle = 0.0f; angle <= (2.0f*GL_PI)*3.0f; angle += 0.1f)
{
x = 50.0f*sin(angle);
y = 50.0f*cos(angle);
// Specify the point and move the Z value up a little
glVertex3f(x, y, z);
z += 0.5f;
}
// Done drawing points
glEnd();
// Restore transformations
glPopMatrix();
// Flush drawing commands
glutSwapBuffers();
}
// This function does any needed initialization on the rendering
// context.
void SetupRC()
{
// Black background
glClearColor(0.0f, 0.0f, 0.0f, 1.0f );
// Set drawing color to green
glColor3f(0.0f, 1.0f, 0.0f);
}
void SpecialKeys(int key, int x, int y)
{
if(key == GLUT_KEY_UP)
xRot-= 5.0f;
if(key == GLUT_KEY_DOWN)
xRot += 5.0f;
if(key == GLUT_KEY_LEFT)
yRot -= 5.0f;
if(key == GLUT_KEY_RIGHT)
yRot += 5.0f;
if(key > 356.0f)
xRot = 0.0f;
if(key < -1.0f)
xRot = 355.0f;
if(key > 356.0f)
yRot = 0.0f;
if(key < -1.0f)
yRot = 355.0f;
// Refresh the Window
glutPostRedisplay();
}
void ChangeSize(int w, int h)
{
GLfloat nRange = 1000.0f;
// Prevent a divide by zero
if(h == 0)
h = 1;
// Set Viewport to window dimensions
glViewport(0, 0, w, h);
// Reset projection matrix stack
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// Establish clipping volume (left, right, bottom, top, near, far)
if (w <= h)
glOrtho (-nRange, nRange, -nRange*h/w, nRange*h/w, -nRange, nRange);
else
glOrtho (-nRange*w/h, nRange*w/h, -nRange, nRange, -nRange, nRange);
// Reset Model view matrix stack
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutCreateWindow("Points Example");
glutReshapeFunc(ChangeSize);
glutSpecialFunc(SpecialKeys);
glutDisplayFunc(RenderScene);
SetupRC();
glutMainLoop();
return 0;
}