Why do my particles appear in the wrong spot?

Particle systems use room coordinates by default. If you pass camera-local coordinates (mouse_x can be either depending on context), particles spawn somewhere off-screen. Use part_emitter_burst with explicit room x/y.

part_system_position vs region?

part_system_position offsets the entire system. Use 0,0 to keep system at origin and emit at world-coord points via emitter regions.

Can I draw particles at GUI level?

part_system_layer or part_system_drawit during Draw GUI lets you render at GUI coordinates. Useful for HUD particle effects that follow the screen, not the world.

Fix: GameMaker Particle System World vs Room Coordinate Confusion

Quick answer: Particle systems use room coordinates. Pass x/y directly when spawning at an instance. For GUI/HUD particles, draw the system in Draw GUI events with GUI coords.

Spawn particles at the player. They appear in the corner. The coords passed were screen-relative (e.g. device_mouse_x_to_gui) instead of room.

The Symptom

Particles emit at unexpected position. Usually at room (0,0) or in a fixed corner of the screen.

The Fix

/// In obj_player Step
part_emitter_burst(part_sys, part_emitter, ps_shape_rectangle, x - 8, y - 8, x + 8, y + 8, part_type, 5);

x and y here are the instance’s room coordinates. The emitter region uses room coords too. Particles spawn around the player.

HUD Particles

/// In obj_hud Draw GUI event
part_system_position(hud_sys, 0, 0);
part_system_drawit(hud_sys);

System drawn during Draw GUI uses GUI coordinates. Useful for menus, screen-edge effects.

Verifying

Spawn at player position. Particles appear at player. Move camera; particles still emit at the world position the player occupies.

“Room coords for world. GUI coords for HUD. Don’t mix.”

Related Issues

For asset precache, see precache. For surface lost, see surface lost.

Right space. Particles spawn where intended.