Summary of updates to enemies.h & enemies.c

Explanation of the enemies.h and enemies.c System

These two files work together to define, create, and update all enemy sprites in the game.
The header file (enemies.h) declares the variables and functions that other parts of the program can use, while the source file (enemies.c) contains the actual logic that spawns enemies and updates their movement each frame.

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1. enemies.h — Interface and Declarations

enemies.h provides the public interface for the enemy system. It declares:

Enemy sprite pointers

extern Sprite* fly;

extern Sprite* snail;

extern Sprite* bee;

extern Sprite* crab;

These point to the actual sprite objects after they are created. Other files can reference these pointers if needed (e.g., for collisions).

Position and velocity arrays

extern fix32 enemy_x[4];

extern fix32 enemy_velx[4];

extern fix32 enemy_y[4];

These arrays store each enemy’s X position, Y position, and horizontal movement speed.
Index meaning:

• 0 → fly
• 1 → snail
• 2 → bee
• 3 → crab

Functions

extern void createEnemies();

extern void manageEnemies();

• createEnemies() — Creates all enemy sprites and assigns their palettes.
• manageEnemies() — Updates their positions every frame.

The header protects itself with include guards to prevent multiple-inclusion issues.

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2. enemies.c — Implementation of Enemy Logic

enemies.c defines and initializes the data declared in the header.

Static enemy data initialization

The four enemies start with hard-coded positions and velocities:

enemy_x = {50, 30, 70, 90}

enemy_y = {80, 40, 120, 180}

enemy_velx = {1.5, -0.5, 2, -0.5}

This means each enemy will move horizontally at a different speed and direction.

2.1. createEnemies() — Spawns the enemy sprites

This function:

1. Loads palette data for snail and bee using:
2. PAL_setPalette(PAL2, ...);
3. PAL_setPalette(PAL1, ...);
4. Creates each enemy sprite at its initial position:
5. fly = SPR_addSprite(&img_fly, ... );
6. snail = SPR_addSprite(&img_snail, ...);
7. bee = SPR_addSprite(&img_bee, ...);
8. crab = SPR_addSprite(&img_crab, ...);

Each sprite is also assigned a palette and tile attributes.

2.2. manageEnemies() — Updates movement every frame

This function performs two things:

A. Movement update

Every enemy’s X coordinate is updated by its velocity:

enemy_x[i] += enemy_velx[i];

B. Sprite repositioning

After updating the logic data, the function applies the new positions to the actual sprites:

SPR_setPosition(fly, fix32ToInt(enemy_x[0]), fix32ToInt(enemy_y[0]));

SPR_setPosition(snail, ... );

SPR_setPosition(bee, ... );

SPR_setPosition(crab, ... );

This is what makes the enemies visually move on the screen.