Nes_Ppu_Rendering.h

// NES PPU emulator graphics rendering

// Nes_Emu 0.7.0

#ifndef NES_PPU_RENDERING_H
#define NES_PPU_RENDERING_H

#include "Nes_Ppu_Impl.h"

class Nes_Ppu_Rendering : public Nes_Ppu_Impl {
	typedef Nes_Ppu_Impl base;
public:
	Nes_Ppu_Rendering();
	
	int sprite_limit;
	
	byte* host_pixels;
	long host_row_bytes;
	
protected:
	
	long sprite_hit_found; // -1: sprite 0 didn't hit, 0: no hit so far, > 0: y * 341 + x
	void draw_background( int start, int count );
	void draw_sprites( int start, int count );
	
private:

	void draw_scanlines( int start, int count, byte* pixels, long pitch, int mode );
	void draw_background_( int count );
	
	// destination for draw functions; avoids extra parameters
	byte* scanline_pixels; 
	long scanline_row_bytes;
	
	// fill/copy
	void fill_background( int count );
	void clip_left( int count );
	void save_left( int count );
	void restore_left( int count );
	
	// sprites
	enum { max_sprites = 64 };
	byte sprite_scanlines [image_height]; // number of sprites on each scanline
	void draw_sprites_( int start, int count );
	bool sprite_hit_possible( int scanline ) const;
	void check_sprite_hit( int begin, int end );
};

inline Nes_Ppu_Rendering::Nes_Ppu_Rendering()
{
	sprite_limit = 8;
	host_pixels = NULL;
}

inline void Nes_Ppu_Rendering::draw_sprites( int start, int count )
{
	assert( host_pixels );
	draw_scanlines( start, count, host_pixels + host_row_bytes * start, host_row_bytes, 2 );
}

#endif