GameMaker Studio 2: Complete Platformer Tutorial (Part 7: Transitions)

Video Title

GameMaker Studio 2: Complete Platformer Tutorial (Part 7: Transitions)

Storyline / Context

This tutorial focuses on implementing smooth screen transitions between levels in a platformer game made with GameMaker Studio 2. The goal is to move the player from one room (level) to another using a visually appealing slide transition effect.

Gameplay Highlights & Features Covered

• Creating an invisible, persistent transition controller object that manages transitions across rooms.
• Implementing black bar slide transitions that cover and reveal the screen during level changes.
• Using enums to manage different transition modes (off, next, go to specific room, restart, intro).
• Drawing GUI elements (black bars) that animate during transitions, independent of the camera.
• Adding easing math to make the transition animations smooth and natural (fast start, slow end).
• Using a script (slide_transition) to trigger transitions easily from anywhere in the game.
• Setting up collision triggers that initiate transitions when the player reaches certain areas.
• Temporarily disabling player control during transitions to avoid input issues.
• Restarting the game with a transition effect.
• Debugging common mistakes such as forgetting to add the transition object to the room or forgetting to enable visibility for draw events.

Key Tips & Strategies

• Persistent Object: Make the transition controller object persistent so it carries over between rooms without being destroyed.
• Enums for Modes: Use enums to clearly define transition states, making the code easier to read and manage.
• Draw GUI Event: Use the Draw GUI event to draw transition elements so they remain fixed on screen regardless of camera movement.
• Easing Transitions: Implement easing by gradually changing the transition percentage with math functions to avoid linear, robotic movement.
• Switch Statement: Use a switch statement for clean handling of different transition modes instead of multiple if-else conditions.
• Script Arguments: Create a reusable script with optional arguments for mode and target room to centralize transition logic.
• Player Control: Add a boolean flag has_control to the player object to enable/disable input during transitions.
• Instance Creation Code: Use instance creation code in the room editor to set unique properties like target rooms on trigger objects without creating multiple object types.
• Debugging: Always remember to place your transition controller object in the first room and ensure it is visible to allow draw events to run.

Step-by-Step Guide to Implement Transitions

• Duplicate your first room to create a second level for testing.
• Create a persistent, invisible transition controller object (o_transition).
• In the controller’s create event:
  • Get screen width and height using display_get_gui_width() and display_get_gui_height().
  • Calculate half the screen height.
  • Define an enum for transition modes (OFF, NEXT, GO_TO, RESTART, INTRO).
  • Initialize variables like percent (progress of transition) and target (target room).
• In the step event:
  • Update percent based on the current mode with easing math.
  • Use a switch statement to handle actions when percent reaches 0 or 1 (switch modes, change rooms, restart game).
• In the draw GUI event:
  • Draw two black rectangles that slide from top and bottom based on percent.
  • Optionally display debug text showing transition progress.
• Create a reusable script slide_transition(mode, target) that sets the mode and target on the transition controller.
• Modify player input code to respect a has_control flag to disable input during transitions.
• Create a trigger object with a collision event with the player that calls slide_transition with the appropriate mode and target room.
• Place the transition controller object in the first room and ensure it is visible.
• Test transitions by moving the player into trigger zones and pressing keys to restart.

Common Mistakes & Debugging

• Forgetting to add the transition controller object to the room.
• Not enabling the visible checkbox on the transition controller object (draw events won’t fire if invisible).
• Accessing variables from the wrong object instance (use other. in collision events).
• Not setting the target room in the instance creation code for trigger objects.
• Forgetting to disable player input during transitions leading to unintended behavior.

Additional Notes

• The tutorial emphasizes good coding practices like using enums and switch statements to improve code clarity.
• The presenter suggests using variables instead of hardcoded numbers for easier tweaking.
• The transitions are designed to be flexible and reusable for various types of room changes (next room, specific room, restart).
• The presenter leaves some mistakes in the video intentionally to show real-world debugging and learning moments.

Featured Gamer / Source

• Tutorial by Shaun Spalding (YouTube creator, GameMaker expert)
• Patreon supporters acknowledged at the end (including Dan in a Mule, Alex Ray, Charles Montgomery, Angel Rodriguez, Harold Guidry, Nathaniel)