// Copyright (c) 2013- PPSSPP Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0 or later versions.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official git repository and contact information can be found at
// https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.

#include "GPU/Common/DrawEngineCommon.h"
#include "GPU/Common/SplineCommon.h"
#include "GPU/ge_constants.h"
#include "GPU/GPUState.h"

DrawEngineCommon::~DrawEngineCommon() { }

struct Plane {
	float x, y, z, w;
	void Set(float _x, float _y, float _z, float _w) { x = _x; y = _y; z = _z; w = _w; }
	float Test(float f[3]) const { return x * f[0] + y * f[1] + z * f[2] + w; }
};

static void PlanesFromMatrix(float mtx[16], Plane planes[6]) {
	planes[0].Set(mtx[3]-mtx[0], mtx[7]-mtx[4], mtx[11]-mtx[8], mtx[15]-mtx[12]);  // Right
	planes[1].Set(mtx[3]+mtx[0], mtx[7]+mtx[4], mtx[11]+mtx[8], mtx[15]+mtx[12]);  // Left
	planes[2].Set(mtx[3]+mtx[1], mtx[7]+mtx[5], mtx[11]+mtx[9], mtx[15]+mtx[13]);  // Bottom
	planes[3].Set(mtx[3]-mtx[1], mtx[7]-mtx[5], mtx[11]-mtx[9], mtx[15]-mtx[13]);  // Top
	planes[4].Set(mtx[3]+mtx[2], mtx[7]+mtx[6], mtx[11]+mtx[10], mtx[15]+mtx[14]); // Near
	planes[5].Set(mtx[3]-mtx[2], mtx[7]-mtx[6], mtx[11]-mtx[10], mtx[15]-mtx[14]); // Far
}

// This code is HIGHLY unoptimized!
//
// It does the simplest and safest test possible: If all points of a bbox is outside a single of
// our clipping planes, we reject the box. Tighter bounds would be desirable but would take more calculations.
bool DrawEngineCommon::TestBoundingBox(void* control_points, int vertexCount, u32 vertType) {
	SimpleVertex *corners = (SimpleVertex *)(decoded + 65536 * 12);
	float *verts = (float *)(decoded + 65536 * 18);

	// Try to skip NormalizeVertices if it's pure positions. No need to bother with a vertex decoder
	// and a large vertex format.
	if ((vertType & 0xFFFFFF) == GE_VTYPE_POS_FLOAT) {
		// memcpy(verts, control_points, 12 * vertexCount);
		verts = (float *)control_points;
	} else if ((vertType & 0xFFFFFF) == GE_VTYPE_POS_8BIT) {
		const s8 *vtx = (const s8 *)control_points;
		for (int i = 0; i < vertexCount * 3; i++) {
			verts[i] = vtx[i] * (1.0f / 128.0f);
		}
	} else if ((vertType & 0xFFFFFF) == GE_VTYPE_POS_16BIT) {
		const s16 *vtx = (const s16*)control_points;
		for (int i = 0; i < vertexCount * 3; i++) {
			verts[i] = vtx[i] * (1.0f / 32768.0f);
		}
	} else {
		// Simplify away bones and morph before proceeding
		u8 *temp_buffer = decoded + 65536 * 24;
		NormalizeVertices((u8 *)corners, temp_buffer, (u8 *)control_points, 0, vertexCount, vertType);
		// Special case for float positions only.
		const float *ctrl = (const float *)control_points;
		for (int i = 0; i < vertexCount; i++) {
			verts[i * 3] = corners[i].pos.x;
			verts[i * 3 + 1] = corners[i].pos.y;
			verts[i * 3 + 2] = corners[i].pos.z;
		}
	}

	Plane planes[6];

	float world[16];
	float view[16];
	float worldview[16];
	float worldviewproj[16];
	ConvertMatrix4x3To4x4(world, gstate.worldMatrix);
	ConvertMatrix4x3To4x4(view, gstate.viewMatrix);
	Matrix4ByMatrix4(worldview, world, view);
	Matrix4ByMatrix4(worldviewproj, worldview, gstate.projMatrix);
	PlanesFromMatrix(worldviewproj, planes);
	for (int plane = 0; plane < 6; plane++) {
		int inside = 0;
		int out = 0;
		for (int i = 0; i < vertexCount; i++) {
			// Here we can test against the frustum planes!
			float value = planes[plane].Test(verts + i * 3);
			if (value < 0)
				out++;
			else
				inside++;
		}

		if (inside == 0) {
			// All out
			return false;
		}

		// Any out. For testing that the planes are in the right locations.
		// if (out != 0) return false;
	}

	return true;
}