Summary of "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)