untitled2dshooter/src/sprite.c

#include <gb/gb.h>
#include <stdlib.h>
#include <stdio.h>
#include "./vec.h"
#include "./constants.h"
#include "./flags.h"
#include "./map.h"


#define LYO 8
#define GET_TILE_INDEX_BY_COORD(x, y)	((((y) / PIXELS_PER_TILE) * 20) + ((x) / PIXELS_PER_TILE))

typedef struct Sprites {
	int gb_sprite_index;
	int frames_since_last_dash;
	int frames_since_last_jump;
	int bitmap_index_prev;
	int bitmap_index;
	int bitmap_indexes[8];
	int bitmap_prop[8];
	int has_diag_sprites;
	int has_joypad;
	char name[20];
	int collision_offset[8][12];
	UVec pos;
	Vec vel;
	Vec acc;
} Sprite;


void sprite_iter_frame(Sprite *sprite, Map *map, int joypad, unsigned int *fc);
void sprite_draw_to_screen(Sprite *sprite);
void sprite_update_bitmap(Sprite *sprite);


// update a sprite for stuff that changes every frame
void sprite_iter_frame(Sprite *sprite, Map *map, int joypad, unsigned int *fc)
{
	unsigned int colx, coly;
	UVec original_position;

	// target displacement is sprite->vel but may collide, giving actual displacment

	if (sprite->frames_since_last_jump <= JUMP_TIMEOUT_FRAMES) sprite->frames_since_last_jump++;
	if (sprite->frames_since_last_dash <= DASH_TIMEOUT_FRAMES) sprite->frames_since_last_dash++;

	if (*fc % 2 == 0) {
		sprite->vel.y += GRAV_ACC;
		*fc = 0;
	}

	// player move left/right
	if ((joypad & J_RIGHT) && (sprite->vel.x < TERM_VELX)) sprite->acc.x = 1;
	else if ((joypad & J_LEFT) && (sprite->vel.x > -TERM_VELX)) sprite->acc.x = -1;
	else sprite->acc.x = -sprite->vel.x/abs(sprite->vel.x);
	sprite->vel.x += sprite->acc.x;

	// player dash
	if ((joypad & J_B) && (sprite->frames_since_last_dash > DASH_TIMEOUT_FRAMES)) {
		int frames_since_last_dash_copy = sprite->frames_since_last_dash;
		sprite->frames_since_last_dash = 0;

		if ((joypad & J_LEFT) && !(joypad & (J_UP | J_RIGHT | J_DOWN))) {
			sprite->vel.x = -DASH_VELL;
		} else if ((joypad & J_RIGHT) && !(joypad & (J_UP | J_LEFT | J_DOWN))) {
			sprite->vel.x = DASH_VELL;
		} else if ((joypad & J_UP) && !(joypad & (J_RIGHT | J_LEFT | J_DOWN))) {
			sprite->vel.y = -DASH_VELL;
		} else if ((joypad & J_DOWN) && !(joypad & (J_UP | J_LEFT | J_RIGHT))) {
			sprite->vel.y = DASH_VELL;
		} else if ((joypad & J_RIGHT) && (joypad & J_UP)) {
			sprite->vel.x = DASH_VELD;
			sprite->vel.y = -DASH_VELD;
		} else if ((joypad & J_LEFT) && (joypad & J_UP)) {
			sprite->vel.x = -DASH_VELD;
			sprite->vel.y = -DASH_VELD;
		} else if ((joypad & J_LEFT) && (joypad & J_DOWN)) {
			sprite->vel.x = -DASH_VELD;
			sprite->vel.y = DASH_VELD;
		} else if ((joypad & J_RIGHT) && (joypad & J_DOWN)) {
			sprite->vel.x = DASH_VELD;
			sprite->vel.y = DASH_VELD;
		} else {
			// if player doesn't hold the right buttons to dash, don't dash and set the
			// frames_since_last_dash counter back to what it was before
			sprite->frames_since_last_dash = frames_since_last_dash_copy;
		}
	}

	// slow down sprite in kind of realistic way
	// (in real life i think it's drag is proportional to sprite->vel square but not
	// sure if that is worth the compute yet cause everythign else is shit)
	if (sprite->vel.y > TERM_VELY) sprite->vel.y   =  TERM_VELY;
	if (sprite->vel.y < -TERM_VELY) sprite->vel.y += (abs(sprite->vel.y)-TERM_VELY)/TERM_VELY_DIVISOR;

	int *offsets = sprite->collision_offset[sprite->bitmap_index];
	// jump if on platform
	if ((joypad & J_A) && (sprite->frames_since_last_jump > JUMP_TIMEOUT_FRAMES)) {
		coly = map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[3]-LYO+1)];
		if (!coly) coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[3]-LYO+1)];
		if(coly) {
			sprite->vel.y = -JUMP_VEL;
			sprite->frames_since_last_jump = 0;
		}
	}

	original_position.x = sprite->pos.x;
	original_position.y = sprite->pos.y;
	// check if following the path by the velocity will lead to a collision

	// if no velocity component, pretend sprite has already collided
	colx = sprite->vel.x == 0;
	coly = sprite->vel.y == 0;

	//for (int step = collision_check_steps; step >= 0; step--) {
	if(sprite->vel.y != 0){
		sprite->pos.y = original_position.y + sprite->vel.y;

		if (sprite->vel.y < 0) {
			coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[1]-LYO)];
			if (!coly) coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[1]-LYO)];
		} else if (sprite->vel.y > 0) {
			coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[3]-LYO)];
			if (!coly) coly += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[3]-LYO)];
		}
		
		if (coly) sprite->pos.y = original_position.y;
	}

	if(sprite->vel.x != 0) {
		sprite->pos.x = original_position.x + sprite->vel.x;

		if (sprite->vel.x < 0) {
			colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[1]-LYO)];
			if(!colx) colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[0], sprite->pos.y - offsets[3]-LYO)];
		} else if (sprite->vel.x > 0) {
			colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[1]-LYO)];
			if(!colx) colx += map->data[GET_TILE_INDEX_BY_COORD(sprite->pos.x - offsets[2], sprite->pos.y - offsets[3]-LYO)];
		}

		if (colx) sprite->pos.x = original_position.x;
	}

	sprite_update_bitmap(sprite);
	sprite_draw_to_screen(sprite);
}

void sprite_update_bitmap(Sprite *sprite)
{

	sprite->bitmap_index_prev = sprite->bitmap_index;

	     if ((sprite->vel.y > 0) && (sprite->vel.x > 0)) sprite->bitmap_index = SI_DOWN_RIGHT;
	else if ((sprite->vel.y < 0) && (sprite->vel.x > 0)) sprite->bitmap_index = SI_UP_RIGHT;
	else if ((sprite->vel.y > 0) && (sprite->vel.x < 0)) sprite->bitmap_index = SI_DOWN_LEFT;
	else if ((sprite->vel.y < 0) && (sprite->vel.x < 0)) sprite->bitmap_index = SI_UP_LEFT;

	else if ( sprite->vel.y < 0)                         sprite->bitmap_index = SI_UP;
	else if ( sprite->vel.y > 0)                         sprite->bitmap_index = SI_DOWN;
	else if ( sprite->vel.x > 0)                         sprite->bitmap_index = SI_RIGHT;
	else if ( sprite->vel.x < 0)                         sprite->bitmap_index = SI_LEFT;
}

void sprite_draw_to_screen(Sprite *sprite)
{
	int bmi = sprite->bitmap_index;

	if (sprite->bitmap_index_prev != bmi) {
		set_sprite_tile(sprite->gb_sprite_index, sprite->bitmap_indexes[bmi]);
		set_sprite_prop(sprite->gb_sprite_index, sprite->bitmap_prop[bmi]);
	}
	move_sprite(sprite->gb_sprite_index, sprite->pos.x, sprite->pos.y);
}