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/*  rasterizer_canvas_gles2.h                                            */
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#ifndef RASTERIZERCANVASGLES2_H
#define RASTERIZERCANVASGLES2_H

#include "rasterizer_canvas_base_gles2.h"

class RasterizerSceneGLES2;

class RasterizerCanvasGLES2 : public RasterizerCanvasBaseGLES2 {

	// used to determine whether we use hardware transform (none)
	// software transform all verts, or software transform just a translate
	// (no rotate or scale)
	enum TransformMode {
		TM_NONE,
		TM_ALL,
		TM_TRANSLATE,
	};

	// pod versions of vector and color and RID, need to be 32 bit for vertex format
	struct BatchVector2 {
		float x, y;
		void set(const Vector2 &p_o) {
			x = p_o.x;
			y = p_o.y;
		}
		void to(Vector2 &r_o) const {
			r_o.x = x;
			r_o.y = y;
		}
	};

	struct BatchColor {
		float r, g, b, a;
		void set(const Color &p_c) {
			r = p_c.r;
			g = p_c.g;
			b = p_c.b;
			a = p_c.a;
		}
		bool operator==(const BatchColor &p_c) const {
			return (r == p_c.r) && (g == p_c.g) && (b == p_c.b) && (a == p_c.a);
		}
		bool operator!=(const BatchColor &p_c) const { return (*this == p_c) == false; }
		bool equals(const Color &p_c) const {
			return (r == p_c.r) && (g == p_c.g) && (b == p_c.b) && (a == p_c.a);
		}
		const float *get_data() const { return &r; }
		String to_string() const;
	};

	struct BatchVertex {
		// must be 32 bit pod
		BatchVector2 pos;
		BatchVector2 uv;
	};

	struct BatchVertexColored : public BatchVertex {
		// must be 32 bit pod
		BatchColor col;
	};

	struct Batch {
		enum CommandType : uint32_t {
			BT_DEFAULT,
			BT_RECT,
		};

		CommandType type;
		uint32_t first_command; // also item reference number
		uint32_t num_commands;
		uint32_t first_quad;
		uint32_t batch_texture_id;
		BatchColor color;
	};

	struct BatchTex {
		enum TileMode : uint32_t {
			TILE_OFF,
			TILE_NORMAL,
			TILE_FORCE_REPEAT,
		};
		RID RID_texture;
		RID RID_normal;
		TileMode tile_mode;
		BatchVector2 tex_pixel_size;
		uint32_t flags;
	};

	// items in a list to be sorted prior to joining
	struct BSortItem {
		// have a function to keep as pod, rather than operator
		void assign(const BSortItem &o) {
			item = o.item;
			z_index = o.z_index;
		}
		Item *item;
		int z_index;
	};

	// batch item may represent 1 or more items
	struct BItemJoined {
		uint32_t first_item_ref;
		uint32_t num_item_refs;

		Rect2 bounding_rect;

		// note the z_index  may only be correct for the first of the joined item references
		// this has implications for light culling with z ranged lights.
		int16_t z_index;

		// these are defined in RasterizerStorageGLES2::Shader::CanvasItem::BatchFlags
		uint16_t flags;

		// we are always splitting items with lots of commands,
		// and items with unhandled primitives (default)
		bool use_hardware_transform() const { return num_item_refs == 1; }
	};

	struct BItemRef {
		Item *item;
		Color final_modulate;
	};

	struct BLightRegion {
		void reset() {
			light_bitfield = 0;
			shadow_bitfield = 0;
			too_many_lights = false;
		}
		uint64_t light_bitfield;
		uint64_t shadow_bitfield;
		bool too_many_lights; // we can only do light region optimization if there are 64 or less lights
	};

	struct BatchData {
		BatchData();
		void reset_flush() {
			batches.reset();
			batch_textures.reset();
			vertices.reset();

			total_quads = 0;
			total_color_changes = 0;
		}

		GLuint gl_vertex_buffer;
		GLuint gl_index_buffer;

		uint32_t max_quads;
		uint32_t vertex_buffer_size_units;
		uint32_t vertex_buffer_size_bytes;
		uint32_t index_buffer_size_units;
		uint32_t index_buffer_size_bytes;

		RasterizerArrayGLES2<BatchVertex> vertices;
		RasterizerArrayGLES2<BatchVertexColored> vertices_colored;
		RasterizerArrayGLES2<Batch> batches;
		RasterizerArrayGLES2<Batch> batches_temp; // used for translating to colored vertex batches
		RasterizerArray_non_pod_GLES2<BatchTex> batch_textures; // the only reason this is non-POD is because of RIDs

		bool use_colored_vertices;

		RasterizerArrayGLES2<BItemJoined> items_joined;
		RasterizerArrayGLES2<BItemRef> item_refs;

		// items are sorted prior to joining
		RasterizerArrayGLES2<BSortItem> sort_items;

		// counts
		int total_quads;

		// we keep a record of how many color changes caused new batches
		// if the colors are causing an excessive number of batches, we switch
		// to alternate batching method and add color to the vertex format.
		int total_color_changes;

		// if the shader is using MODULATE, we prevent baking color so the final_modulate can
		// be read in the shader.
		// if the shader is reading VERTEX, we prevent baking vertex positions with extra matrices etc
		// to prevent the read position being incorrect.
		// These flags are defined in RasterizerStorageGLES2::Shader::CanvasItem::BatchFlags
		uint32_t joined_item_batch_flags;

		// measured in pixels, recalculated each frame
		float scissor_threshold_area;

		// diagnose this frame, every nTh frame when settings_diagnose_frame is on
		bool diagnose_frame;
		String frame_string;
		uint32_t next_diagnose_tick;
		uint64_t diagnose_frame_number;

		// whether to join items across z_indices - this can interfere with z ranged lights,
		// so has to be disabled in some circumstances
		bool join_across_z_indices;

		// global settings
		bool settings_use_batching; // the current use_batching (affected by flash)
		bool settings_use_batching_original_choice; // the choice entered in project settings
		bool settings_flash_batching; // for regression testing, flash between non-batched and batched renderer
		bool settings_diagnose_frame; // print out batches to help optimize / regression test
		int settings_max_join_item_commands;
		float settings_colored_vertex_format_threshold;
		int settings_batch_buffer_num_verts;
		bool settings_scissor_lights;
		float settings_scissor_threshold; // 0.0 to 1.0
		int settings_item_reordering_lookahead;
		bool settings_use_single_rect_fallback;
		int settings_light_max_join_items;

		// uv contraction
		bool settings_uv_contract;
		float settings_uv_contract_amount;

		// only done on diagnose frame
		void reset_stats() {
			stats_items_sorted = 0;
			stats_light_items_joined = 0;
		}

		// frame stats (just for monitoring and debugging)
		int stats_items_sorted;
		int stats_light_items_joined;
	} bdata;

	struct RenderItemState {
		RenderItemState() { reset(); }
		void reset();
		Item *current_clip;
		RasterizerStorageGLES2::Shader *shader_cache;
		bool rebind_shader;
		bool prev_use_skeleton;
		int last_blend_mode;
		RID canvas_last_material;
		Color final_modulate;

		// used for joining items only
		BItemJoined *joined_item;
		bool join_batch_break;
		BLightRegion light_region;

		// 'item group' is data over a single call to canvas_render_items
		int item_group_z;
		Color item_group_modulate;
		Light *item_group_light;
		Transform2D item_group_base_transform;
	} _render_item_state;

	struct FillState {
		void reset() {
			// don't reset members that need to be preserved after flushing
			// half way through a list of commands
			curr_batch = 0;
			batch_tex_id = -1;
			texpixel_size = Vector2(1, 1);
			contract_uvs = false;
		}
		Batch *curr_batch;
		int batch_tex_id;
		bool use_hardware_transform;
		bool contract_uvs;
		Vector2 texpixel_size;
		Color final_modulate;
		TransformMode transform_mode;
		TransformMode orig_transform_mode;

		// support for extra matrices
		bool extra_matrix_sent; // whether sent on this item (in which case software transform can't be used untl end of item)
		int transform_extra_command_number_p1; // plus one to allow fast checking against zero
		Transform2D transform_combined; // final * extra
	};

public:
	virtual void canvas_render_items_begin(const Color &p_modulate, Light *p_light, const Transform2D &p_base_transform);
	virtual void canvas_render_items_end();
	virtual void canvas_render_items(Item *p_item_list, int p_z, const Color &p_modulate, Light *p_light, const Transform2D &p_base_transform);
	virtual void canvas_begin();
	virtual void canvas_end();

private:
	// legacy codepath .. to remove after testing
	void _canvas_render_item(Item *p_ci, RenderItemState &r_ris);
	void _canvas_item_render_commands(Item *p_item, Item *p_current_clip, bool &r_reclip, RasterizerStorageGLES2::Material *p_material);

	// high level batch funcs
	void canvas_render_items_implementation(Item *p_item_list, int p_z, const Color &p_modulate, Light *p_light, const Transform2D &p_base_transform);
	void render_joined_item(const BItemJoined &p_bij, RenderItemState &r_ris);
	void record_items(Item *p_item_list, int p_z);
	void join_items(Item *p_item_list, int p_z);
	void join_sorted_items();
	bool try_join_item(Item *p_ci, RenderItemState &r_ris, bool &r_batch_break);
	void render_joined_item_commands(const BItemJoined &p_bij, Item *p_current_clip, bool &r_reclip, RasterizerStorageGLES2::Material *p_material, bool p_lit);
	void render_batches(Item::Command *const *p_commands, Item *p_current_clip, bool &r_reclip, RasterizerStorageGLES2::Material *p_material);
	bool prefill_joined_item(FillState &r_fill_state, int &r_command_start, Item *p_item, Item *p_current_clip, bool &r_reclip, RasterizerStorageGLES2::Material *p_material);
	void flush_render_batches(Item *p_first_item, Item *p_current_clip, bool &r_reclip, RasterizerStorageGLES2::Material *p_material);

	// low level batch funcs
	void _batch_translate_to_colored();
	int _batch_find_or_create_tex(const RID &p_texture, const RID &p_normal, bool p_tile, int p_previous_match);
	RasterizerStorageGLES2::Texture *_get_canvas_texture(const RID &p_texture) const;
	void _batch_upload_buffers();
	void _batch_render_rects(const Batch &p_batch, RasterizerStorageGLES2::Material *p_material);
	BatchVertex *_batch_vertex_request_new() { return bdata.vertices.request(); }
	Batch *_batch_request_new(bool p_blank = true);

	bool _detect_batch_break(Item *p_ci);
	void _software_transform_vertex(BatchVector2 &r_v, const Transform2D &p_tr) const;
	void _software_transform_vertex(Vector2 &r_v, const Transform2D &p_tr) const;
	TransformMode _find_transform_mode(const Transform2D &p_tr) const;
	void _prefill_default_batch(FillState &r_fill_state, int p_command_num, const Item &p_item);

	// sorting
	void sort_items();
	bool sort_items_from(int p_start);
	bool _sort_items_match(const BSortItem &p_a, const BSortItem &p_b) const;

	// light scissoring
	bool _light_find_intersection(const Rect2 &p_item_rect, const Transform2D &p_light_xform, const Rect2 &p_light_rect, Rect2 &r_cliprect) const;
	bool _light_scissor_begin(const Rect2 &p_item_rect, const Transform2D &p_light_xform, const Rect2 &p_light_rect) const;
	void _calculate_scissor_threshold_area();

	// no need to compile these in in release, they are unneeded outside the editor and only add to executable size
#ifdef DEBUG_ENABLED
	void diagnose_batches(Item::Command *const *p_commands);
	String get_command_type_string(const Item::Command &p_command) const;
#endif

public:
	void initialize();
	RasterizerCanvasGLES2();
};

//////////////////////////////////////////////////////////////

// Default batches will not occur in software transform only items
// EXCEPT IN THE CASE OF SINGLE RECTS (and this may well not occur, check the logic in prefill_join_item TYPE_RECT)
// but can occur where transform commands have been sent during hardware batch
inline void RasterizerCanvasGLES2::_prefill_default_batch(FillState &r_fill_state, int p_command_num, const Item &p_item) {
	if (r_fill_state.curr_batch->type == Batch::BT_DEFAULT) {
		// don't need to flush an extra transform command?
		if (!r_fill_state.transform_extra_command_number_p1) {
			// another default command, just add to the existing batch
			r_fill_state.curr_batch->num_commands++;
		} else {
#if defined(TOOLS_ENABLED) && defined(DEBUG_ENABLED)
			if (r_fill_state.transform_extra_command_number_p1 != p_command_num) {
				WARN_PRINT_ONCE("_prefill_default_batch : transform_extra_command_number_p1 != p_command_num");
			}
#endif
			// if the first member of the batch is a transform we have to be careful
			if (!r_fill_state.curr_batch->num_commands) {
				// there can be leading useless extra transforms (sometimes happens with debug collision polys)
				// we need to rejig the first_command for the first useful transform
				r_fill_state.curr_batch->first_command += r_fill_state.transform_extra_command_number_p1 - 1;
			}

			// we do have a pending extra transform command to flush
			// either the extra transform is in the prior command, or not, in which case we need 2 batches
			r_fill_state.curr_batch->num_commands += 2;

			r_fill_state.transform_extra_command_number_p1 = 0; // mark as sent
			r_fill_state.extra_matrix_sent = true;

			// the original mode should always be hardware transform ..
			// test this assumption
			//CRASH_COND(r_fill_state.orig_transform_mode != TM_NONE);
			r_fill_state.transform_mode = r_fill_state.orig_transform_mode;

			// do we need to restore anything else?
		}
	} else {
		// end of previous different type batch, so start new default batch

		// first consider whether there is a dirty extra matrix to send
		if (r_fill_state.transform_extra_command_number_p1) {
			// get which command the extra is in, and blank all the records as it no longer is stored CPU side
			int extra_command = r_fill_state.transform_extra_command_number_p1 - 1; // plus 1 based
			r_fill_state.transform_extra_command_number_p1 = 0;
			r_fill_state.extra_matrix_sent = true;

			// send the extra to the GPU in a batch
			r_fill_state.curr_batch = _batch_request_new();
			r_fill_state.curr_batch->type = Batch::BT_DEFAULT;
			r_fill_state.curr_batch->first_command = extra_command;
			r_fill_state.curr_batch->num_commands = 1;

			// revert to the original transform mode
			// e.g. go back to NONE if we were in hardware transform mode
			r_fill_state.transform_mode = r_fill_state.orig_transform_mode;

			// reset the original transform if we are going back to software mode,
			// because the extra is now done on the GPU...
			// (any subsequent extras are sent directly to the GPU, no deferring)
			if (r_fill_state.orig_transform_mode != TM_NONE) {
				r_fill_state.transform_combined = p_item.final_transform;
			}

			// can possibly combine batch with the next one in some cases
			// this is more efficient than having an extra batch especially for the extra
			if ((extra_command + 1) == p_command_num) {
				r_fill_state.curr_batch->num_commands = 2;
				return;
			}
		}

		// start default batch
		r_fill_state.curr_batch = _batch_request_new();
		r_fill_state.curr_batch->type = Batch::BT_DEFAULT;
		r_fill_state.curr_batch->first_command = p_command_num;
		r_fill_state.curr_batch->num_commands = 1;
	}
}

inline void RasterizerCanvasGLES2::_software_transform_vertex(BatchVector2 &r_v, const Transform2D &p_tr) const {
	Vector2 vc(r_v.x, r_v.y);
	vc = p_tr.xform(vc);
	r_v.set(vc);
}

inline void RasterizerCanvasGLES2::_software_transform_vertex(Vector2 &r_v, const Transform2D &p_tr) const {
	r_v = p_tr.xform(r_v);
}

inline RasterizerCanvasGLES2::TransformMode RasterizerCanvasGLES2::_find_transform_mode(const Transform2D &p_tr) const {
	// decided whether to do translate only for software transform
	if ((p_tr.elements[0].x == 1.0) &&
			(p_tr.elements[0].y == 0.0) &&
			(p_tr.elements[1].x == 0.0) &&
			(p_tr.elements[1].y == 1.0)) {
		return TM_TRANSLATE;
	}

	return TM_ALL;
}

inline bool RasterizerCanvasGLES2::_sort_items_match(const BSortItem &p_a, const BSortItem &p_b) const {
	const Item *a = p_a.item;
	const Item *b = p_b.item;

	if (b->commands.size() != 1)
		return false;

	// tested outside function
	//	if (a->commands.size() != 1)
	//		return false;

	const Item::Command &cb = *b->commands[0];
	if (cb.type != Item::Command::TYPE_RECT)
		return false;

	const Item::Command &ca = *a->commands[0];
	// tested outside function
	//	if (ca.type != Item::Command::TYPE_RECT)
	//		return false;

	const Item::CommandRect *rect_a = static_cast<const Item::CommandRect *>(&ca);
	const Item::CommandRect *rect_b = static_cast<const Item::CommandRect *>(&cb);

	if (rect_a->texture != rect_b->texture)
		return false;

	return true;
}

#endif // RASTERIZERCANVASGLES2_H