/*************************************************************************/
/*  rendering_server_canvas_helper.cpp                                   */
/*************************************************************************/
/*                         This file is part of:                         */
/*                          PANDEMONIUM ENGINE                           */
/*             https://github.com/Relintai/pandemonium_engine            */
/*************************************************************************/
/* Copyright (c) 2022-present Péter Magyar.                              */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
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/*************************************************************************/

#include "rendering_server_canvas_helper.h"

#include "servers/rendering/rasterizer.h"
#include "servers/rendering_server.h"

LocalVector<MultiRect> RenderingServerCanvasHelper::_tilemap_multirects;
Mutex RenderingServerCanvasHelper::_tilemap_mutex;

bool RenderingServerCanvasHelper::_multirect_enabled = true;

void MultiRect::add_rect(RID p_canvas_item, const Rect2 &p_rect, RID p_texture, const Rect2 &p_src_rect, const Color &p_modulate, bool p_transpose, RID p_normal_map, bool p_clip_uv) {
	bool new_common_data = true;

	Rect2 rect = p_rect;
	Rect2 source = p_src_rect;

	// To make the rendering code as efficient as possible,
	// a single MultiRect command should have identical flips and transpose etc.
	// If these change, it flushes the previous multirect and starts a new one.
	uint32_t flags = 0;

	if (p_rect.size.x < 0) {
		flags |= RasterizerCanvas::CANVAS_RECT_FLIP_H;
		rect.size.x = -rect.size.x;
	}
	if (source.size.x < 0) {
		flags ^= RasterizerCanvas::CANVAS_RECT_FLIP_H;
		source.size.x = -source.size.x;
	}
	if (p_rect.size.y < 0) {
		flags |= RasterizerCanvas::CANVAS_RECT_FLIP_V;
		rect.size.y = -rect.size.y;
	}
	if (source.size.y < 0) {
		flags ^= RasterizerCanvas::CANVAS_RECT_FLIP_V;
		source.size.y = -source.size.y;
	}

	if (p_transpose) {
		flags |= RasterizerCanvas::CANVAS_RECT_TRANSPOSE;
		SWAP(rect.size.x, rect.size.y);
	}

	if (p_clip_uv) {
		flags |= RasterizerCanvas::CANVAS_RECT_CLIP_UV;
	}

	RenderingServerCanvasHelper::State s;
	s.item = p_canvas_item;
	s.texture = p_texture;
	s.modulate = p_modulate;
	s.normal_map = p_normal_map;
	s.flags = flags;

	if (!is_empty()) {
		if ((state != s) ||
				(rects.size() >= MAX_RECTS)) {
			flush();
		} else {
			new_common_data = false;
		}
	}

	if (new_common_data) {
		state = s;
	}

	rects.push_back(rect);
	sources.push_back(source);

	// Legacy path
	if (!RenderingServerCanvasHelper::_multirect_enabled) {
		flush();
	}
}

void MultiRect::begin(const RenderingServerCanvasHelper::State &p_state) {
	DEV_CHECK_ONCE(!rects.size());
	rects.clear();
	sources.clear();

	state = p_state;
	state_set = true;
}

uint32_t MultiRect::flags_from_rects(Rect2 &r_rect, Rect2 &r_source) {
	uint32_t flags = 0;

	if (r_rect.size.x < 0) {
		flags |= RasterizerCanvas::CANVAS_RECT_FLIP_H;
		r_rect.size.x = -r_rect.size.x;
	}
	if (r_rect.size.y < 0) {
		flags |= RasterizerCanvas::CANVAS_RECT_FLIP_V;
		r_rect.size.y = -r_rect.size.y;
	}

	if (r_source.size.x < 0) {
		flags ^= RasterizerCanvas::CANVAS_RECT_FLIP_H;
		r_source.size.x = -r_source.size.x;
	}
	if (r_source.size.y < 0) {
		flags ^= RasterizerCanvas::CANVAS_RECT_FLIP_V;
		r_source.size.y = -r_source.size.y;
	}

	return flags;
}

bool MultiRect::add_pre_flipped(const Rect2 &p_rect, const Rect2 &p_src_rect) {
	if (rects.is_full()) {
		return false;
	}
	*rects.request() = p_rect;
	*sources.request() = p_src_rect;
	return true;
}

bool MultiRect::add(const Rect2 &p_rect, const Rect2 &p_src_rect, bool p_commit_on_flip_change) {
	if (rects.is_full()) {
		return false;
	}

	Rect2 rect = p_rect;
	Rect2 source = p_src_rect;

	uint32_t flags = flags_from_rects(rect, source);

	if (state_set) {
		// if we are changing these flips, we can no longer continue the same multirect
		if ((state.flags & (RasterizerCanvas::CANVAS_RECT_FLIP_H | RasterizerCanvas::CANVAS_RECT_FLIP_V)) != flags) {
			// different state requires a new multirect
			return false;
		}

	} else {
		state.flags |= flags;
		state_set = true;
	}

	*rects.request() = rect;
	*sources.request() = source;
	return true;
}

void MultiRect::flush() {
	if (!is_empty()) {
		if (RenderingServerCanvasHelper::_multirect_enabled) {
			RenderingServer::get_singleton()->canvas_item_add_texture_multirect_region(state.item, rects, state.texture, sources, state.modulate, state.flags, state.normal_map);

		} else {
			// legacy path
			bool transpose = state.flags & RasterizerCanvas::CANVAS_RECT_TRANSPOSE;
			bool clip_uv = state.flags & RasterizerCanvas::CANVAS_RECT_CLIP_UV;

			for (uint32_t n = 0; n < rects.size(); n++) {
				RenderingServer::get_singleton()->canvas_item_add_texture_rect_region(state.item, rects[n], state.texture, sources[n], state.modulate, transpose, state.normal_map, clip_uv);
			}
		}

		rects.clear();
		sources.clear();
	}
	state_set = false;

	// This may not be necessary (if needing to eek out maximum speed).
	state.flags = 0;
}

void RenderingServerCanvasHelper::tilemap_begin() {
	if (_multirect_enabled) {
		_tilemap_mutex.lock();
	}
}

void RenderingServerCanvasHelper::tilemap_add_rect(RID p_canvas_item, const Rect2 &p_rect, RID p_texture, const Rect2 &p_src_rect, const Color &p_modulate, bool p_transpose, RID p_normal_map, bool p_clip_uv) {
	if (!_multirect_enabled) {
		RenderingServer::get_singleton()->canvas_item_add_texture_rect_region(p_canvas_item, p_rect, p_texture, p_src_rect, p_modulate, p_transpose, p_normal_map, p_clip_uv);
		return;
	}

	Rect2 rect = p_rect;
	Rect2 source = p_src_rect;

	// To make the rendering code as efficient as possible,
	// a single MultiRect command should have identical flips and transpose etc.
	// If these change, it flushes the previous multirect and starts a new one.
	uint32_t flags = MultiRect::flags_from_rects(rect, source);

	if (p_transpose) {
		flags |= RasterizerCanvas::CANVAS_RECT_TRANSPOSE;
		SWAP(rect.size.x, rect.size.y);
	}

	if (p_clip_uv) {
		flags |= RasterizerCanvas::CANVAS_RECT_CLIP_UV;
	}

	State state;
	state.item = p_canvas_item;
	state.texture = p_texture;
	state.modulate = p_modulate;
	state.normal_map = p_normal_map;
	state.flags = flags;

	// attempt to add to existing multirect
	for (int n = _tilemap_multirects.size() - 1; n >= 0; n--) {
		MultiRect &mr = _tilemap_multirects[n];

		// matches state?
		if (mr.state == state) {
			// add .. this may fail if the multirect is full
			if (mr.add_pre_flipped(rect, source)) {
				return;
			}
		}

		// disallow if we overlap a multirect
		if (mr.overlaps(rect)) {
			break;
		}
	}

	// create new multirect
	_tilemap_multirects.resize(_tilemap_multirects.size() + 1);
	MultiRect &mr = _tilemap_multirects[_tilemap_multirects.size() - 1];
	mr.begin(state);
	mr.add_pre_flipped(rect, source);
}

void RenderingServerCanvasHelper::tilemap_end() {
	if (!_multirect_enabled) {
		return;
	}

	for (uint32_t n = 0; n < _tilemap_multirects.size(); n++) {
		_tilemap_multirects[n].flush();
	}

	_tilemap_multirects.clear();
	_tilemap_mutex.unlock();
}