Code: 3d_underwater_world/worldobjects.cpp

This is an example OpenGL SDL application which creates an animated 3D underwater world (screenshot), with "Thunderbird 4" with headlights moving on a spline path, a randomly generated sand terrain, sunken ship/submarine/treasure chest models, and swaying fish and seaweed. It is designed to demonstrate basic OpenGL features, and the structure is as follows:

#include "worldobjects.h"

/* WorldObject class
   Base class for all objects in the 3D enviroment.
*/
WorldObject::WorldObject():
    bearing(0.0),
    height(1.0),
    width(1.0),
    depth(1.0)
{
}

void WorldObject::draw(CameraView* view)
{
     // if visible then draw
     
     glPushMatrix();
     // translate to correct position
     glTranslatef(pos.x, pos.y, pos.z);
     // rotate to correct bearing
     glRotatef(bearing, 0, 1, 0);
     // draw
     drawInternal();
     glPopMatrix();
     
     // draw end
     #ifdef DEBUG
     Mat4 m;
     m.setI();
     m.rotate(bearing, 0, 1, 0);
     m.translate(pos.x, pos.y, pos.z);
     Vec3 s(org.x, org.y, org.z);
     m.transform(&s);
     Vec3 f(org.x + width, org.y + height, org.z + depth);
     m.transform(&f);
     glPushMatrix();
     glColor3f(0, 1.0, 0);
     glTranslatef(s.x, s.y, s.z);
     glScalef(0.5, 0.5, 0.5);
     Primitives::drawSphere();
     glPopMatrix();
     glPushMatrix();
     glColor3f(1.0, 0.0, 0);
     glTranslatef(f.x, f.y, f.z);
     glScalef(0.5, 0.5, 0.5);
     Primitives::drawSphere();
     glPopMatrix();
     #endif
}

// check for collision, and if
// one occurs provides the point of
// collision
// position - vertex to check
// direction - direction of vertex as it approached
// result - when returns true contains the point of collision
bool WorldObject::collisionDetect(Vec3* position, Vec3* direction, Vec3* result)
{
     // copy position
     Vec3 loc(position);
     // convert direction to point just infront
     Vec3 obj(position);
     obj.add(direction);
     
     // transform point the local space of this world object
     Mat4 m;
     m.translate(-pos.x, -pos.y, -pos.z);
     m.rotate(-bearing, 0, 1, 0);
     m.transform(&loc);
     m.transform(&obj);
     
     // see if is inside the collision box
     if (isInside(&loc))
     {
         // transformed direction
         Vec3 dir(&obj);
         dir.subtract(&loc);
         dir.norm(); dir.multiply(0.1);
         
         // reverse position, until not infringing
         int i = 0; // limit incase of infinate loop
         while (i < 1000 && isInside(&loc)) {
             loc.subtract(&dir); i++;
         }
         result->set(&loc);
         
         // transform back into normal space
         m.setI();
         m.rotate(bearing, 0, 1, 0);
         m.translate(pos.x, pos.y, pos.z);
         m.transform(result);
                  
         // does collide
         return true;
     }
     
     // no infringment
     return false;
}

// checks if a point in this world object's
// space is inside the collision box.
bool WorldObject::isInside(Vec3* loc)
{
     return (loc->x >= org.x && loc->x <= org.x + width &&
         loc->y >= org.y && loc->y <= org.y + height &&
         loc->z >= org.z && loc->z <= org.z + depth);
}



// single function call to position and setup
// the static object in the scene
void StaticObject::init(float x, float y, float z, float b)
{
    pos.x = x;
    pos.y = y;
    pos.z = z;
    bearing = b;
}

3D Underwater World (using OpenGL and SDL)

worldobjects.cpp