/* Silkworm - Verlet cloth physics in C
 *
 * Copyright (c) 2021 Evan Hemsley
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from
 * the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software in a
 * product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * Evan "cosmonaut" Hemsley <evan@moonside.games>
 *
 */

#ifndef SILKWORM_H
#define SILKWORM_H

#include <math.h>
#include <stdbool.h>
#include <stdint.h>

#ifdef _WIN32
#define SILKWORMAPI __declspec(dllexport)
#define SILKWORMCALL __cdecl
#else
#define SILKWORMAPI
#define SILKWORMCALL
#endif

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

typedef struct Silkworm_Vector2
{
	float x;
	float y;
} Silkworm_Vector2;

typedef struct Silkworm_Node
{
	uint64_t id;
	Silkworm_Vector2 position;
	Silkworm_Vector2 previousPosition;
	Silkworm_Vector2 velocity;
	Silkworm_Vector2 acceleration;
	float mass;
	float friction;
	float radius;
	float pinned;
	float pushFactor;
	bool destroyable;
} Silkworm_Node;

typedef struct Silkworm_Link
{
	uint64_t id;
	Silkworm_Node *a;
	Silkworm_Node *b;
	float distance;
	float tearThreshold;
} Silkworm_Link;

typedef enum Silkworm_ClothTriangleOrientation
{
	UpperLeft,
	BottomRight
} Silkworm_ClothTriangleOrientation;

typedef struct Silkworm_Triangle
{
	uint64_t id;
	Silkworm_Node* a;
	Silkworm_Node* b;
	Silkworm_Node* c;

	uint32_t aHorizontalIndex;
	uint32_t bHorizontalIndex;
	uint32_t cHorizontalIndex;

	uint32_t aVerticalIndex;
	uint32_t bVerticalIndex;
	uint32_t cVerticalIndex;

	Silkworm_ClothTriangleOrientation orientation;
} Silkworm_Triangle;

typedef struct Silkworm_Cloth
{
	uint64_t id;
	float windFactor;

	uint32_t horizontalNodeCount;
	uint32_t verticalNodeCount;

	uint64_t **nodeIndices; /* x by y grid of indices */

	Silkworm_Triangle **triangles; /* array of pointers so we can use NULL */
	uint32_t triangleCount;
} Silkworm_Cloth;

typedef struct Silkworm_Rope
{
	uint32_t nodeCount;

	uint32_t *nodeIndices;
} Silkworm_Rope;

/* Version API */

#define SILKWORM_ABI_VERSION	 0
#define SILKWORM_MAJOR_VERSION   0
#define SILKWORM_MINOR_VERSION	1
#define SILKWORM_PATCH_VERSION	0
#define SILKWORM_COMPILED_VERSION ( \
	(REFRESH_ABI_VERSION * 100 * 100 * 100) + \
	(REFRESH_MAJOR_VERSION * 100 * 100) + \
	(REFRESH_MINOR_VERSION * 100) + \
	(REFRESH_PATCH_VERSION) \
)

SILKWORMAPI void Silkworm_Init();
SILKWORMAPI void Silkworm_Update(double delta);

SILKWORMAPI double Silkworm_CreateNode(double xPosition, double yPosition, double mass, double friction, double radius, double pushFactor);

SILKWORMAPI void Silkworm_NodeSetDestroyable(double nodeId);
SILKWORMAPI void Silkworm_ClothNodePin(double clothId, double i, double j);
SILKWORMAPI void Silkworm_ClothNodeUnpin(double clothId, double i, double j);

SILKWORMAPI double Silkworm_CreateLink(double aId, double bId, double distance, double tearThreshold);

SILKWORMAPI double Silkworm_CreateCloth(double xPosition, double yPosition, double horizontalNodeCount, double verticalNodeCount, double mass, double friction, double windFactor, double tearThreshold);

SILKWORMAPI void Silkworm_SetTriangleBuffer(const char* bufferId);
SILKWORMAPI double Silkworm_ClothFillTriangleBuffer(double clothId, double leftUV, double widthUV, double topUV, double heightUV);

#endif /* SILKWORM_H */