GML-system-movement

Maintained by: Army Armbuster

Thank you for your interest in my movement system.

This is a hybrid collision movement system, consisting of object collisions and/or tileset collisions.

This system features the following:

• 360 degrees sub-pixel movement; rounded in the direction of a hard collision occurring.
• Hard collisions with o_movement_collision objects, and with a tileset.
• Soft collisions between o_movement objects.
• Hard tileset collisions may be configured per o_movement_controller.
• Hard tileset collisions may be disabled per o_movement object(s).
• Hard objects collisions may be disabled per o_movement object(s).
• Soft objects collisions may be disabled per o_movement object(s).
• Corner assisted movement, as configured by a percentage margin of the width and height of the o_movement object.
• o_movement object dimensions may be smaller, equal, or greater than the tileset cell width and/or height set.

Application Overview

Movement is executed with a single (1) script, and three (3) objects make up the hybrid collision movement system.

Application Scripts

• scr_movement_step

Application Objects

• o_movement_collision
• o_movement
• o_movement_controller

Application Scripts

scr_movement_step

This script will execute movement based on the arguments passed, and on the o_movement instance inputs set.

Here is a table of the inputs used, from the highest priority to the lowest priority:

Input	Description
_input_enabled	Must be passed as an argument for enabling movement; friction is applied if set to false
input_x_next_	Internally set as a priority feedback input as enforced by corner assisted movement
input_y_next_	Internally set as a priority feedback input as enforced by corner assisted movement
input_x_	Must be set before this script is called, as defined by player inputs
input_y_	Must be set before this script is called, as defined by player inputs
_input_angle	Must be passed as an argument for the desired movement direction; undefined otherwise

Inputs input_x_next_, input_y_next_, input_x_, and input_y_ are considered cleared when set to 0.

Inputs input_x_ and input_y_ must be set with each begin step event, or at least, before this script is called. Inputs input_x_ and input_y_ will be set to 0 in the end step event.

Inputs are evaluated separately for the x and y axis, meaning a part of _input_angle could still be used for one of the axis' inputs not set as defined in the priority table above _input_angle.

Application Objects

o_movement_collision

This object can be considered to be the standard collision object as we all know.

This object has no events, no variables, and no sprite.

It is recommended to create a child of this object, and then give a sprite to the child object to further use in the project.

o_movement

This object is the main movement object to which the scr_movement_step applies to.

It is recommended to create a child of this object (o_movement_example), as demonstrated in the example project. There may be as many children as the required number of tileset collision configurations. These children may then be further extended into additional children as required by the actual object implementations. This will abstract the tileset collision o_movement_controller object configurations.

Example:

• flying (child of o_movement with one tileset o_movement_controller configuration child)
• ground (child of o_movement with another tileset o_movement_controller configuration child)

These examples may then be extended into additional children as required by the implementation.

A single o_movement_controller object will be assigned to a o_movement object.

Here is a table of the variables and their descriptions:

Variable	Range	Description
z	-	unused
move_angle_	-	current movement angle
move_angle_div_	(0, 360)	move_angle_index_ divisor
move_angle_index_	-	current movement index
move_speed_	-	current movement speed
move_speed_z_	-	unused
move_speed_max_	-	* maximum movement speed
move_speed_max_z_	-	unused
move_accel_	-	* movement acceleration
move_accel_z_	-	unused
move_accel_next_	-	* corner movement acceleration
move_friction_enabled_	-	unused
move_friction_	(0.1, 1.0)	pixel amount by which to apply friction
move_bounce_enabled_	-	enable bounce off collisions
move_bounce_	(0.1, 1.0)	factor by which to adjust movement
input_x_	(-1, 1)	- 1 left, + 1 right
input_x_next_	(-1, 1)	- 1 left, + 1 right
input_x_margin_	(0.1, 0.4)	margin percentage for corner assistance
input_y_	(-1, 1)	- 1 up, + 1 down
input_y_next_	(-1, 1)	- 1 up, + 1 down
input_y_margin_	(0.1, 0.4)	margin percentage for corner assistance
input_z_	(-1, 1)	unused
input_z_next_	(-1, 1)	unused
input_z_margin_	(0.1, 0.4)	unused
collision_controller_	-	* o_movement_controller to use for tileset collisions
collision_enabled_tileset_	-	true to enable tileset collisions, false otherwise
collision_enabled_objects_	-	true to enable objects collisions, false otherwise
collision_enabled_	-	true to enable soft o_movement collisions, false otherwise

* is initially set to undefined, and must be set before the object is used.

o_movement_controller

This object is the main tileset configuration object to which hard tileset collisions apply to.

It is recommended to create a child of this object (o_movement_controller_example), as demonstrated in the example project.

There may be as many children as the required number of tileset collision configurations. See the description of o_movement for more information.

Here is a table of the variables and their descriptions:

Variable	Range	Description
tileset_cell_w_	-	* tileset cell width
tileset_cell_w_	-	* tileset cell width
tileset_layer_	-	* tileset layer name with enclosing ""
tileset_grid_	-	internally used

* is initially set to undefined, and must be set before the object is used.

Miscellaneous

To enable hard collisions between o_movement objects, simply make o_movement a child of o_movement_collision

NOTE! Due to the nature of hard collisions expected to be integer bounded, these hard collisions may not appear 'perfect'.