/*
PHYSICS.C

symbols in this file:
0013FF60 0080:
	_pin_fraction (0000)
0013FFE0 00b0:
	_physics_get_features_in_sphere (0000)
00140090 0070:
	_code_00140090 (0000)
00140100 0110:
	_render_debug_physics (0000)
00140210 0100:
	_physics_instance_new (0000)
00140310 00a0:
	_physics_test_point (0000)
001403B0 0120:
	_physics_test_vector (0000)
001404D0 0150:
	_code_001404d0 (0000)
00140620 0100:
	_code_00140620 (0000)
00140720 0b80:
	_physics_compute_new (0000)
001412A0 0470:
	_code_001412a0 (0000)
00141710 0490:
	_code_00141710 (0000)
00141BA0 0180:
	_code_00141ba0 (0000)
00141D20 01b0:
	_code_00141d20 (0000)
00141ED0 07c0:
	_physics_update_new (0000)
00142690 1430:
	_code_00142690 (0000)
00143AC0 0260:
	_physics_update (0000)
0028BC20 008d:
	??_C@_0IN@ODNFDOFI@mass_point?9?$DOground_material_type@ (0000)
0028BCB0 0021:
	??_C@_0CB@OHGIJBLL@c?3?2halo?2SOURCE?2physics?2physics?4c@ (0000)
0028BCD4 0004:
	__real@45ea6000 (0000)
0028BCD8 0057:
	??_C@_0FH@DDOACPI@unit_definition?9?$DOunit?4blip_type?$DO@ (0000)
0028BD30 0015:
	??_C@_0BF@GMDJIBPD@model_instance_valid?$AA@ (0000)
0028BD48 0010:
	??_C@_0BA@LNKGLGKJ@rotated_forward?$AA@ (0000)
0028BD58 000b:
	??_C@_0L@GBBDLPMF@rotated_up?$AA@ (0000)
0028BD64 000f:
	??_C@_0P@OGJNHPDG@up?$CB?$DNrotated_up?$AA@ (0000)
0028BD74 0019:
	??_C@_0BJ@GEGCJHGH@forward?$CB?$DNrotated_forward?$AA@ (0000)
0028BD90 0004:
	__real@364c6ce0 (0000)
0028BD94 0004:
	__real@34a5b36e (0000)
0028BD98 0004:
	__real@3b33abb1 (0000)
0028BDA0 0008:
	__real@3f80000000000000 (0000)
0028BDA8 0012:
	??_C@_0BC@MDPNAJDL@?$CGangular_velocity?$AA@ (0000)
0028BDBC 0016:
	??_C@_0BG@NPNNHCFI@?$CGangular_acceleration?$AA@ (0000)
0028BDD4 0011:
	??_C@_0BB@IHCLBKLO@?$CGlinear_velocity?$AA@ (0000)
0028BDE8 0015:
	??_C@_0BF@LNOJMOGI@?$CGlinear_acceleration?$AA@ (0000)
0028BE00 001d:
	??_C@_0BN@FOPAIIBD@instance?9?$DOphysics?9?$DOmass?$DO0?40f?$AA@ (0000)
0028BE20 0018:
	??_C@_0BI@HOJEHDKE@?$CGobject?9?$DOobject?4forward?$AA@ (0000)
0028BE38 0013:
	??_C@_0BD@JHPMDDBM@?$CGobject?9?$DOobject?4up?$AA@ (0000)
0028BE4C 001c:
	??_C@_0BM@EKBNDJOG@?$CGtranslational_acceleration?$AA@ (0000)
0028BE68 000d:
	??_C@_0N@EMPCNLII@magic_torque?$AA@ (0000)
0028BE78 000c:
	??_C@_0M@LNGNIFCJ@magic_force?$AA@ (0000)
0030CEB4 002c:
	_global_gravity (0000)
	_global_water_density (0004)
	_global_air_density (0008)
	_global_physics_collision_depth (000c)
	_depths_of_hell (0010)
0045E01A 0001:
	_debug_physics_disable_penetration_freeze (0000)
*/

/* ---------- headers */

#include "cseries.h"
#include "physics.h"

#include "collision_features.h"
#include "objects/object_definitions.h"
#include "objects/objects.h"
#include "physics_definitions.h"
#include "render/render_debug.h"

/* ---------- constants */

/* ---------- macros */

/* ---------- structures */

/* ---------- prototypes */

/* ---------- globals */

real global_gravity = 0.0035651792f;
real global_water_density = 1.0f;
real global_air_density = 0.0011f;
real global_physics_collision_depth = 0.2f;
real_plane3d depths_of_hell =
{
	{ 0.0f, 0.0f, 1.0f },
	-256.0f
};

/* ---------- public code */

real pin_fraction(
	real value,
	real begin,
	real end)
{
	if (begin < end)
	{
		if (value <= begin)
			return 0.0f;
		else if (value >= end)
			return 1.0f;
		else
			return (value - begin) / (end - begin);
	}
	else
	{
		if (value <= end)
			return 1.0f;
		else if (value >= begin)
			return 0.0f;
		else
			return (begin - value) / (begin - end);
	}
}

boolean physics_get_features_in_sphere(
	struct physics_instance const *instance,
	real_point3d const *center,
	real radius,
	real height,
	real width,
	struct collision_feature_list *features)
{
	short mass_point_index;
	real scaled_radius;

	for (mass_point_index = 0;
		mass_point_index < instance->physics->mass_points.count;
		mass_point_index++)
	{
		struct mass_point_definition const *mass_point = TAG_BLOCK_GET_ELEMENT(
			&instance->physics->mass_points,
			mass_point_index,
			struct mass_point_definition);
		real_point3d point;

		matrix4x3_transform_point(&instance->world_matrix, &mass_point->position, &point);

		scaled_radius = mass_point->radius * instance->world_matrix.scale;

		collision_features_from_point(
			&point,
			height,
			scaled_radius + width,
			instance->object_index,
			NONE,
			0,
			NONE,
			NONE,
			features);
	}

	return features->count[_collision_feature_sphere] ||
		features->count[_collision_feature_cylinder] ||
		features->count[_collision_feature_prism];
}

void render_debug_physics(
	struct physics_instance *instance)
{
	struct object_datum *object = object_get(instance->object_index);
	struct object_definition *definition = object_definition_get(object->definition_index);
	real_point3d center_of_mass;
	short mass_point_index;

	matrix4x3_transform_point(
		&instance->world_matrix,
		&instance->physics->center_of_mass,
		&center_of_mass);

	render_debug_vectors(
		TRUE,
		&center_of_mass,
		&instance->world_matrix.forward,
		&instance->world_matrix.up,
		definition->object.bounding_radius);

	for (mass_point_index = 0;
		mass_point_index < instance->physics->mass_points.count;
		mass_point_index++)
	{
		struct mass_point_definition const *mass_point = TAG_BLOCK_GET_ELEMENT(
			&instance->physics->mass_points,
			mass_point_index,
			struct mass_point_definition);
		real_point3d position;
		real_vector3d forward;
		real_vector3d up;

		matrix4x3_transform_point(
			&instance->world_matrix,
			&mass_point->position,
			&position);
		matrix4x3_transform_normal(
			&instance->world_matrix,
			&mass_point->forward,
			&forward);
		matrix4x3_transform_normal(
			&instance->world_matrix,
			&mass_point->up,
			&up);

		render_debug_sphere(
			TRUE,
			&position,
			mass_point->radius,
			global_real_argb_white);
		render_debug_vectors(
			TRUE,
			&position,
			&forward,
			&up,
			mass_point->radius * 0.5f);
	}
}

boolean physics_instance_new(
	struct physics_instance *instance,
	long object_index)
{
	struct object_datum *object = object_get(object_index);
	struct object_definition *definition = object_definition_get(object->definition_index);
	real_point3d center_of_mass;

	if (definition->object.physics.index != NONE)
	{
		instance->object_index = object_index;
		instance->physics = physics_definition_get(definition->object.physics.index);

		instance->world_matrix.scale = 1.0f;
		object_get_origin(object_index, &instance->world_matrix.position);
		object_get_orientation(object_index, &instance->world_matrix.forward, &instance->world_matrix.up);
		cross_product3d(&instance->world_matrix.up, &instance->world_matrix.forward, &instance->world_matrix.left);

		set_real_point3d(&center_of_mass,
			-instance->physics->center_of_mass.x,
			-instance->physics->center_of_mass.y,
			-instance->physics->center_of_mass.z);
		matrix4x3_transform_point(&instance->world_matrix, &center_of_mass, &center_of_mass);
		instance->world_matrix.position = center_of_mass;

		return TRUE;
	}

	return FALSE;
}

boolean physics_test_point(
	struct physics_instance const *instance,
	real_point3d const *point)
{
	real_point3d local_point;
	struct physics_definition const *physics;
	short mass_point_index;

	matrix4x3_inverse_transform_point(&instance->world_matrix, point, &local_point);
	physics = instance->physics;

	for (mass_point_index = 0;
		mass_point_index < physics->mass_points.count;
		mass_point_index++)
	{
		struct mass_point_definition const *mass_point = TAG_BLOCK_GET_ELEMENT(
			&physics->mass_points,
			mass_point_index,
			struct mass_point_definition);

		if (point_in_sphere(&local_point, &mass_point->position, mass_point->radius))
			return TRUE;

		physics = instance->physics;
	}

	return FALSE;
}

boolean physics_test_vector(
	struct physics_instance const *instance,
	real_point3d const *point,
	real_vector3d const *vector,
	struct physics_test_vector_result *result)
{
	boolean hit = FALSE;
	real_point3d local_point;
	real_vector3d local_vector;
	real_vector3d normal;
	short mass_point_index;

	result->t = REAL_MAX;

	matrix4x3_inverse_transform_point(&instance->world_matrix, point, &local_point);
	matrix4x3_inverse_transform_vector(&instance->world_matrix, vector, &local_vector);

	for (mass_point_index = 0;
		mass_point_index < instance->physics->mass_points.count;
		mass_point_index++)
	{
		struct mass_point_definition const *mass_point = TAG_BLOCK_GET_ELEMENT(
			&instance->physics->mass_points,
			mass_point_index,
			struct mass_point_definition);
		real t;

		if (sphere_test_vector3d(
				&mass_point->position,
				mass_point->radius,
				&local_point,
				&local_vector,
				&t,
				&normal) &&
			result->t > t)
		{
			real_point3d intersection;

			result->t = t;
			// Preserve the January inline schedule without emitting a point_from_line3d COMDAT.
			intersection.x = local_vector.i*t + local_point.x;
			intersection.y = local_vector.j*t + local_point.y;
			intersection.z = local_vector.k*t + local_point.z;
			plane3d_from_point_and_normal(
				&result->plane,
				&intersection,
				&normal);
			hit = TRUE;
		}
	}

	if (hit)
		matrix4x3_transform_plane(&instance->world_matrix, &result->plane, &result->plane);

	return hit;
}
/* ---------- private code */