Drawing¶
Drawing in Codea¶
Codea comes with an immediate mode drawing API that forms the basis of rendering both 2D and 3D graphics
The user-defined global draw() function is called once per frame to
update the contents of the screen
The background(r,g,b,a) function is used to clear the background with a given color. When this isn’t called the contents of the background will stay the same as the preivous frame
Codea uses an hybrid-immediate mode drawing system, where various built-in functions can be used to paint objects to the screen when called, such as line(), sprite() and rect()
These functions use the current render state, defined by the current style and matrix in use, which effects things like fill color and stroke color / width
Style¶
The style module contains functions that set the current drawing state
This module uses a fluent syntax, so any call that does not return a value, will instead return the style module itself, allowing multiple style commands to be chained together:
-- Draw a red ellipse with a 5px white stroke
style.push().fill(color.red).stroke(color.white).strokeWidth(5)
ellipse(WIDTH/2, HEIGHT/2, 100, 100)
style.pop()
See style for a complete reference of all functionality
Anywhere <color> is used as a parameter, the following forms can be used:
style.func(r, g, b, a) -- separate color components in the range 0-255
style.func(r, g, b) -- only red, green, blue color components with alpha assumed to be 255
style.func(grey, alpha) -- only greyscale and alpha
style.func(grey) -- only grayscale with alph assumed to be 255
style.func(color) -- a color object
Matrix¶
The matrix module is used to manipulate the current immediate mode transform, view and projection matrices, which can be thought of as object pose, camera pose and perspective
By combining different matrix commands, any 2D or 3D drawing setup can be achieved, and there is also the camera class which can be used on its own or part of a scene for a higher level abstraction