Hi everyone.
I use the below code to create scene with multiple spheres, and with the keyboard method I intend to move only one of them (first one for example). Unfortunately, every time I press a key the whole scene gets redrawn (because of glutPostRedisplay, which recalls the display method). How do I bypass this behavior, so that a single sphere moves and the others keep their old positions? Any help is welcome.
class SolidSphere
{
protected:
std::vector<GLfloat> vertices;
std::vector<GLfloat> normals;
std::vector<GLfloat> texcoords;
std::vector<GLushort> indices;
public:
SolidSphere(float radius, unsigned int rings, unsigned int sectors)
{
float const R = 1.0f / (float)(rings - 1);
float const S = 1.0f / (float)(sectors - 1);
unsigned int r, s;
vertices.resize(rings * sectors * 3);
normals.resize(rings * sectors * 3);
texcoords.resize(rings * sectors * 2);
std::vector<GLfloat>::iterator v = vertices.begin();
std::vector<GLfloat>::iterator n = normals.begin();
std::vector<GLfloat>::iterator t = texcoords.begin();
for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {
float const x = sinf(M_PI * r * R) * cosf(2 * M_PI * s * S);
float const y = sinf(-M_PI_2 + M_PI * r * R );
float const z = sinf(2.0f * M_PI * s * S) * sinf(M_PI * r * R );
*t++ = s*S;
*t++ = r*R;
*v++ = x * radius;
*v++ = y * radius;
*v++ = z * radius;
*n++ = x;
*n++ = y;
*n++ = z;
}
indices.resize(rings * sectors * 6);
std::vector<GLushort>::iterator i = indices.begin();
for(r = 0; r < rings - 1; r++) for(s = 0; s < sectors - 1; s++) {
*i++ = r * sectors + s;
*i++ = (r + 1) * sectors + (s + 1);
*i++ = r * sectors + (s + 1);
*i++ = r * sectors + s;
*i++ = (r + 1) * sectors + s;
*i++ = (r + 1) * sectors + (s + 1);
}
}
void draw(GLfloat x, GLfloat y, GLfloat z)
{
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glTranslatef(x,y,z);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, &vertices[0]);
glNormalPointer(GL_FLOAT, 0, &normals[0]);
glTexCoordPointer(2, GL_FLOAT, 0, &texcoords[0]);
glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_SHORT, &indices[0]);
glPopMatrix();
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_NORMAL_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
}
};
void init()
{
struct Light {
float ambient[4];
float diffuse[4];
float specular[4];
float position[4];
} light = {
{ .2, .2, .2, 1. },
{ .8, .8, .8, 1. },
{ 1., 1., 1., 1. },
{ 1., 1., 1., .0 }
};
struct Material {
float ambient[4];
float diffuse[4];
float specular[4];
float shininess[1];
} material = {
{ .8, .8, .8, 1. },
{ .8, .8, .8, 1. },
{ 1., 1., 1., 1. },
{ 96 }
};
glClearColor(.5, .5, 1., 1.);
glShadeModel(GL_SMOOTH);
glMaterialfv(GL_FRONT_AND_BACK, GL_SHININESS, material.shininess);
glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material.specular);
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, material.diffuse);
glLightfv(GL_LIGHT0, GL_POSITION, light.position);
glLightfv(GL_LIGHT0, GL_AMBIENT, light.ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light.diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light.specular);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_DEPTH_TEST);
glEnable(GL_COLOR_MATERIAL);
}
SolidSphere **createSpheres()
{
SolidSphere **spheres = new SolidSphere*[numSpheres];
for (int i = 0; i < numSpheres; i++)
spheres[i] = new SolidSphere(1, 12, 24);
return spheres;
}
void display()
{
SolidSphere **spheres = createSpheres();
float const win_aspect = (float)win_width / (float)win_height;
glViewport(0, 0, win_width, win_height);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(.6, 0, 0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45, win_aspect, 1, 10);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
for (int i = 0; i < numSpheres; i++)
{
posX = ((float)rand())/RAND_MAX * 4 - 2;
posY = ((float)rand())/RAND_MAX * 4 - 2;
posZ = ((float)rand())/RAND_MAX * 5 - 10;
spheres[i]->draw(posX,posY,posZ);
}
for (int i = 0; i < numSpheres; i++)
{
delete spheres[i];
}
delete[] spheres;
glutSwapBuffers();
}
void keyboard(unsigned char key, int x, int y)
{
switch(key)
{
case 27:
exit(0);
case 'a':
posX -= 0.05f;
glutPostRedisplay();
break;
case 'd':
posX += 0.05f;
glutPostRedisplay();
break;
case 's':
posY -= 0.05f;
glutPostRedisplay();
break;
case 'w':
posY += 0.05f;
glutPostRedisplay();
break;
case 'x':
posZ -= 0.05f;
glutPostRedisplay();
break;
case 'z':
posZ += 0.05f;
glutPostRedisplay();
break;
}
}