// written in the D programming language

module samples.Springies;

import chipmunkd.chipmunk;

import samples.ChipmunkDemo;

static cpSpace *space;

static cpFloat
springForce(cpConstraint *spring, cpFloat dist)
{
	cpFloat clamp = 20.0f;
	return cpfclamp(cpDampedSpringGetRestLength(spring) - dist, -clamp, clamp)*cpDampedSpringGetStiffness(spring);
}

static cpConstraint *
new_spring(cpBody *a, cpBody *b, cpVect anchr1, cpVect anchr2, cpFloat restLength, cpFloat stiff, cpFloat damp)
{
	cpConstraint *spring = cpDampedSpringNew(a, b, anchr1, anchr2, restLength, stiff, damp);
	cpDampedSpringSetSpringForceFunc(spring, &springForce);
	
	return spring;
}

static void
update(int ticks)
{
	enum int steps = 1;
	enum cpFloat dt = 1.0f/60.0f/cast(cpFloat)steps;
	
	for(int i=0; i<steps; i++){
		cpSpaceStep(space, dt);
	}
}

static cpBody *
add_bar(cpVect a, cpVect b, int group)
{
	cpVect center = cpvmult(cpvadd(a, b), 1.0f/2.0f);
	cpFloat length = cpvlength(cpvsub(b, a));
	cpFloat mass = length/160.0f;
	
	cpBody *_body = cpSpaceAddBody(space, cpBodyNew(mass, mass*length*length/12.0f));
	_body.p = center;
	
	cpShape *shape = cpSpaceAddShape(space, cpSegmentShapeNew(_body, cpvsub(a, center), cpvsub(b, center), 10.0f));
	shape.group = group;
	
	return _body;
}

static cpSpace *
init()
{
	space = cpSpaceNew();
	cpBody *staticBody = &space.staticBody;
	
	cpBody *body1  = add_bar(cpv(-240,  160), cpv(-160,   80), 1);
	cpBody *body2  = add_bar(cpv(-160,   80), cpv( -80,  160), 1);
	cpBody *body3  = add_bar(cpv(   0,  160), cpv(  80,    0), 0);
	cpBody *body4  = add_bar(cpv( 160,  160), cpv( 240,  160), 0);
	cpBody *body5  = add_bar(cpv(-240,    0), cpv(-160,  -80), 2);
	cpBody *body6  = add_bar(cpv(-160,  -80), cpv( -80,    0), 2);
	cpBody *body7  = add_bar(cpv( -80,    0), cpv(   0,    0), 2);
	cpBody *body8  = add_bar(cpv(   0,  -80), cpv(  80,  -80), 0);
	cpBody *body9  = add_bar(cpv( 240,   80), cpv( 160,    0), 3);
	cpBody *body10 = add_bar(cpv( 160,    0), cpv( 240,  -80), 3);
	cpBody *body11 = add_bar(cpv(-240,  -80), cpv(-160, -160), 4);
	cpBody *body12 = add_bar(cpv(-160, -160), cpv( -80, -160), 0);
	cpBody *body13 = add_bar(cpv(   0, -160), cpv(  80, -160), 0);
	cpBody *body14 = add_bar(cpv( 160, -160), cpv( 240, -160), 0);
	
	cpSpaceAddConstraint(space, cpPivotJointNew2( body1,  body2, cpv( 40,-40), cpv(-40,-40)));
	cpSpaceAddConstraint(space, cpPivotJointNew2( body5,  body6, cpv( 40,-40), cpv(-40,-40)));
	cpSpaceAddConstraint(space, cpPivotJointNew2( body6,  body7, cpv( 40, 40), cpv(-40,  0)));
	cpSpaceAddConstraint(space, cpPivotJointNew2( body9, body10, cpv(-40,-40), cpv(-40, 40)));
	cpSpaceAddConstraint(space, cpPivotJointNew2(body11, body12, cpv( 40,-40), cpv(-40,  0)));
	
	cpFloat stiff = 100.0f;
	cpFloat damp = 0.5f;
	cpSpaceAddConstraint(space, new_spring(staticBody,  body1, cpv(-320,  240), cpv(-40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody,  body1, cpv(-320,   80), cpv(-40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody,  body1, cpv(-160,  240), cpv(-40, 40), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody,  body2, cpv(-160,  240), cpv( 40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody,  body2, cpv(   0,  240), cpv( 40, 40), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody,  body3, cpv(  80,  240), cpv(-40, 80), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody,  body4, cpv(  80,  240), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody,  body4, cpv( 320,  240), cpv( 40,  0), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody,  body5, cpv(-320,   80), cpv(-40, 40), 0.0f, stiff, damp));
	
	cpSpaceAddConstraint(space, new_spring(staticBody,  body9, cpv( 320,  80), cpv( 40, 40), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody, body10, cpv( 320,   0), cpv( 40,-40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody, body10, cpv( 320,-160), cpv( 40,-40), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody, body11, cpv(-320,-160), cpv(-40, 40), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody, body12, cpv(-240,-240), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody, body12, cpv(   0,-240), cpv( 40,  0), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody, body13, cpv(   0,-240), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody, body13, cpv(  80,-240), cpv( 40,  0), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring(staticBody, body14, cpv(  80,-240), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody, body14, cpv( 240,-240), cpv( 40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(staticBody, body14, cpv( 320,-160), cpv( 40,  0), 0.0f, stiff, damp));

	cpSpaceAddConstraint(space, new_spring( body1,  body5, cpv( 40,-40), cpv(-40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body1,  body6, cpv( 40,-40), cpv( 40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body2,  body3, cpv( 40, 40), cpv(-40, 80), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body3,  body4, cpv(-40, 80), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body3,  body4, cpv( 40,-80), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body3,  body7, cpv( 40,-80), cpv( 40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body3,  body7, cpv(-40, 80), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body3,  body8, cpv( 40,-80), cpv( 40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body3,  body9, cpv( 40,-80), cpv(-40,-40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body4,  body9, cpv( 40,  0), cpv( 40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body5, body11, cpv(-40, 40), cpv(-40, 40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body5, body11, cpv( 40,-40), cpv( 40,-40), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body7,  body8, cpv( 40,  0), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body8, body12, cpv(-40,  0), cpv( 40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body8, body13, cpv(-40,  0), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body8, body13, cpv( 40,  0), cpv( 40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring( body8, body14, cpv( 40,  0), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(body10, body14, cpv( 40,-40), cpv(-40,  0), 0.0f, stiff, damp));
	cpSpaceAddConstraint(space, new_spring(body10, body14, cpv( 40,-40), cpv(-40,  0), 0.0f, stiff, damp));
	
	return space;
}

static void
destroy()
{
	cpSpaceFreeChildren(space);
	cpSpaceFree(space);
}

chipmunkDemo Springies = {
	"Springies",
	null,
	&init,
	&update,
	&destroy,
};