/* Copyright (c) 2007 Scott Lembcke
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
 
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#include "chipmunk.h"
#include "drawSpace.h"
#include "ChipmunkDemo.h"

static cpSpace *space;
static cpBody *staticBody;

// Init is called by the demo code to set up the demo.
static cpSpace *
init(void)
{
	// Create an infinite mass body to attach ground segments and other static geometry to.
	// We won't be adding this body to the space, because we don't want it to be simulated at all.
	// Adding bodies to the space simulates them. (fall under the influence of gravity, etc)
	// We want the static body to stay right where it is at all times.
	staticBody = cpBodyNew(INFINITY, INFINITY);
	
	// Create a space, a space is a simulation world. It simulates the motions of rigid bodies,
	// handles collisions between them, and simulates the joints between them.
	space = cpSpaceNew();
	
	// Lets set some parameters of the space:
	// More iterations make the simulation more accurate but slower
	space->iterations = 10;
	// These parameters tune the efficiency of the collision detection.
	// For more info: http://code.google.com/p/chipmunk-physics/wiki/cpSpace
	cpSpaceResizeStaticHash(space, 30.0f, 1000);
	cpSpaceResizeActiveHash(space, 30.0f, 1000);
	// Give it some gravity
	space->gravity = cpv(0, -100);
	
	// Create A ground segment along the bottom of the screen
	cpShape *ground = cpSegmentShapeNew(staticBody, cpv(-320,-240), cpv(320,-240), 0.0f);
	// Set some parameters of the shape.
	// For more info: http://code.google.com/p/chipmunk-physics/wiki/cpShape
	ground->e = 1.0f; ground->u = 1.0f;
	ground->layers = NOT_GRABABLE_MASK; // Used by the Demo mouse grabbing code
	// Add the shape to the space as a static shape
	// If a shape never changes position, add it as static so Chipmunk knows it only needs to
	// calculate collision information for it once when it is added.
	// Do not change the postion of a static shape after adding it.
	cpSpaceAddStaticShape(space, ground);
	
	// Add a moving circle object.
	cpFloat radius = 15.0f;
	cpFloat mass = 10.0f;
	// This time we need to give a mass and moment of inertia when creating the circle.
	cpBody *ballBody = cpBodyNew(mass, cpMomentForCircle(mass, 0.0f, radius, cpvzero));
	// Set some parameters of the body:
	// For more info: http://code.google.com/p/chipmunk-physics/wiki/cpBody
	ballBody->p = cpv(0, -240 + radius+5);
	// Add the body to the space so it will be simulated and move around.
	cpSpaceAddBody(space, ballBody);
	
	
	// Add a circle shape for the ball.
	// Shapes are always defined relative to the center of gravity of the body they are attached to.
	// When the body moves or rotates, the shape will move with it.
	// Additionally, all of the cpSpaceAdd*() functions return the thing they added so you can create and add in one go.
	cpShape *ballShape = cpSpaceAddShape(space, cpCircleShapeNew(ballBody, radius, cpvzero));
	ballShape->e = 0.0f; ballShape->u = 0.9f;
	
	return space;
}

// Update is called by the demo code each frame.
static void
update(int ticks)
{
	// Chipmunk allows you to use a different timestep each frame, but it works much better when you use a fixed timestep.
	// An excellent article on why fixed timesteps for game logic can be found here: http://gafferongames.com/game-physics/fix-your-timestep/
	cpSpaceStep(space, 1.0f/60.0f);
}

// destroy is called by the demo code to free all the memory we've allocated
static void
destroy(void)
{
	cpBodyFree(staticBody);
	cpSpaceFreeChildren(space);
	cpSpaceFree(space);
}

chipmunkDemo Simple = {
	"Simple",
	NULL,
	init,
	update,
	destroy,
};