defold-orthographic

Orthographic camera API for the Defold game engine. The API makes it super easy to convert screen to world coordinates, smoothly follow a game object and create a screen shake effect. This project is inspired by the camera component of the Phaser engine.

The project is shipped with an example that shows all the features of the orthographic camera. Test the example app in your browser.

Installation

You can use the orthograpic camera in your own project by adding this project as a Defold library dependency. Open your game.project file and in the dependencies field under project add:

https://github.com/britzl/defold-orthographic/archive/master.zip

Or point to the ZIP file of a specific release.

Basic usage

Add the camera.go to a collection. Depending on your use case you can either add the camera as a child of a game object to have the camera always follow that object or you could add the camera as a root game object and move or animate it manually using code or using the Orthographic Camera API (see below).

The camera will send view projection messages to the render script while it is enabled. Make sure your render script handles this message! See the section on render script integration below.

Configuration

Select the script component attached to the camera.go to modify the properties. The camera has the following configurable properties:

near_z (number) and far_z (number)

This is the near and far z-values used in the projection matrix, ie the near and far clipping plane. Anything with a z-value inside this range will be drawn by the render script.

projection (hash)

The camera can be configured to support different kinds of orthographic projections. The default projection (aptly named DEFAULT) uses the same orthographic projection matrix as in the default render script (ie aspect ratio isn't maintained and content is stretched). Additional custom projections can be added, see camera.add_projector() below. Refer to the render script of the example project to see an example of a projector that maintains aspect ratio.

enabled (boolean)

This controls if the camera is enabled by default or not. Send enable and disable messages to the script or use go.set(id, "enable", true|false) to toggle this value.

Render script integration

While the camera is enabled it will send set_view_projection messages once per frame to the render script. The message is the same as that of the camera component, meaning that it contains id, view and projection values. Make sure that these values are handled and used properly in the render script:

function update(self)
	...
	render.set_view(self.view)
	render.set_projection(self.projection)
	-- draw using the view and projection
	...
end

function on_message(self, message_id, message, sender)
	if message_id == hash("set_view_projection") then
		self.camera_id = message.id
		self.view = message.view
		self.projection = message.projection
	end
end

An alternative approach is to ignore the set_view_projection message and directly read the view and projection from the camera in the render script:

local camera = require "orthographic.camera"

function update(self)
	...
	local camera_id = id of your camera
	render.set_view(camera.get_view(camera_id))
	render.set_projection(camera.get_projection(camera_id))
	-- draw using the view and projection
	...
end

The project includes a render script that does the above mentioned integration of the Orthographic Camera API. Use it as it is or copy it into your project and make whatever modifications that you need.

The Orthographic Camera API

The API can be used in two ways:

Calling functions on the camera.lua module
Sending messages to the camera.script

camera.shake(camera_id, [intensity], [duration], [direction], [cb])

Shake the camera.

PARAMETERS

camera_id (hash|url)
intensity (number) - Intensity of the shake, in percent of screen. Defaults to 0.05
duration (number) - Duration of the shake, in seconds. Defaults to 0.5
direction (hash) - Direction of the shake. Possible values: both, horizontal, vertical. Defaults to both.
cb (function) - Function to call when the shake has finished. Optional.

camera.follow(camera_id, target, [lerp])

Follow a game object.

PARAMETERS

camera_id (hash|url)
target (hash|url) - Game object to follow
lerp (number) - Lerp from current position to target position with lerp as t. Optional.

camera.unfollow(camera_id)

Stop following a game object.

PARAMETERS

camera_id (hash|url)

camera.deadzone(camera_id, left, top, right, bottom)

If following a game object this will add a deadzone around the camera position where the camera position will not update. If the target moves to the edge of the deadzone the camera will start to follow until the target returns within the bounds of the deadzone.

PARAMETERS

camera_id (hash|url)
left (number) - Number of pixels to the left of the camera
top (number) - Number of pixels above the camera
right (number) - Number of pixels to the right of the camera
bottom (number) - Number of pixels below the camera

camera.bounds(camera_id, left, top, right, bottom)

Limits the camera position to within the specified rectangle.

PARAMETERS

camera_id (hash|url)
left (number) - Left edge of the camera bounds
top (number) - Top edge of camera bounds
right (number) - Right edge of camera bounds
bottom (number) - Bottom edge of camera bounds

camera.screen_to_world(camera_id, x, y, [z])

Translate screen coordinates to world coordinates, based on the view and projection of the camera.

PARAMETERS

camera_id (hash|url)
screen (vector3) Screen coordinates to convert

RETURN

world_coords (vector3) World coordinates

camera.world_to_screen(camera_id, x, y)

Translate world coordinates to screen coordinates, based on the view and projection of the camera. This is useful when manually culling game objects and you need to determine if a world coordinate will be visible or not.

PARAMETER

camera_id (hash|url)
world (vector3) World coordinates to convert

RETURN

screen_coords (vector3) Screen coordinates

camera.unproject(view, projection, screen)

Translate screen coordinates to world coordinates using the specified view and projection.

PARAMETERS

view (matrix4)
projection (matrix4)
screen (vector3) Screen coordinates to convert

RETURN

world_coords (vector3) Note: Same v3 object as passed in as argument

camera.project(view, projection, world)

Translate world coordinates to screen coordinates using the specified view and projection.

PARAMETERS

view (matrix4)
projection (matrix4)
world (vector3) World coordinates to convert

RETURN

screen_coords (vector3) Note: Same v3 object as passed in as argument

camera.add_projector(projector_id, projector_fn)

Add a custom projector that can be used by cameras in your project (see configuration above).

PARAMETERS

projector_id (hash) - Id of the projector. Used as a value in the projection field of the camera script.
projector_fn (function) - The function to call when a projection matrix is needed for the camera. The function will receive the id, near_z and far_z values of the camera.

shake

Message equivalent to camera.shake(). Supports intensity, duration and direction.

shake_complete

Message sent back to the sender of a shake message when the shake has completed.

follow

Message equivalent to camera.follow(). Supports target and lerp.

unfollow

Message equivalent to camera.unfollow().

deadzone

Message equivalent to camera.deadzone(). Supports left, right, bottom, top.

bounds

Message equivalent to camera.bounds(). Supports left, right, bottom, top.

enable

Enable the camera. While the camera is enabled it will update it's view and projection and send these to the render script.

disable

Disable the camera.

License

This library is released under the same Terms and Conditions as Defold.

nicloay / defold-orthographic Goto Github PK