7.7
2d Graphics with syndicate-gl
| (require syndicate-gl/2d) | package: syndicate |
1 Creating Dataspaces
procedure
((2d-dataspace [ #:width width #:height height #:exit? exit?]) boot-actions ...) → any/c width : number? = 640 height : number? = 480 exit? : boolean? = #t boot-actions : action?
Create and run a frame% with dimensions width and
height controlled by a Syndicate dataspace. The dataspace is
initialized with the given boot-actions. Runs (blocking)
while the frame% is active. If exit? is true, calls
(exit 0) once the dataspace exits.
procedure
(spawn-keyboard-integrator [#:meta-level meta-level]) → actor?
meta-level : natural-number/c = 1
KeyboardIntegrator. Integrates key-events into key-pressed assertions. The
meta-level must point to the root of the 2d dataspace, which defaults
to assuming is one level removed.
2 Changing the State
procedure
(update-scene prelude postlude [ #:meta-level meta-level]) → patch? prelude : (listof (sealof (listof instruction))) postlude : (listof (sealof (listof instruction))) meta-level : natural-number/c = 1
Create a patch retracting any previous scene assertion and asserting a new scene
from the prelude and postlude instructions. The
meta-level must point to the root of the 2d dataspace, which defaults
to assuming is one level removed.
procedure
(update-sprites [ #:meta-level meta-level] sprites ...) → patch? meta-level : natural-number/c = 1 sprites : sprite?
Create a patch retracting any previous sprite assertion(s) and asserting each of
sprites. The meta-level must point to the root of the 2d
dataspace, which defaults to assuming is one level removed.
3 Data Structures
Shared state maintained by dataspace. Describes current window dimensions.
struct
(struct frame-event ( counter timestamp elapsed-ms target-frame-rate)) counter : any/c timestamp : any/c elapsed-ms : any/c target-frame-rate : any/c
Message sent by dataspace. Describes frame about to be rendered.
struct
code : (or/c char? key-code-symbol?) press? : boolean? key : (sealof (instanceof/c key-event%))
Message sent by dataspace. Describes a key event. key is a sealed
key-event%. press? is #t when the key is pressed (or
autorepeated!), and #f when it is released.
struct
(struct key-pressed (code))
code : (or/c char? key-code-symbol?)
Assertion. Indicates that the named key is held down. See role
KeyboardIntegrator and spawn-keyboard-integrator.
Shared state maintained by program. prelude and postlude are
to be sealed instruction lists. It is an error to have more than exactly
one active such record at a given time.
Shared state maintained by program. z is to be a number, negative
toward camera. instructions to be a sealed instruction list.
Create a sprite from a z number and a list of instructions.
struct
(struct request-gc ())
Message. Requests that the OpenGL loop perform a major
garbage-collection while *pausing the simulation’s real-time
correspondence*. This lets a GC take place without such severe
simulation glitches as happen when doing it in-world.
procedure
(simple-sprite z x y w h i) → sprite?
z : number? x : number? y : number? w : number? h : number?
i :
(or/c (instanceof/c bitmap%) pict? image?)
Create a sprite from image i at position (x, y) with
width w, height h, and z-index z.
4 Instructions
'(rotate degrees) where degrees is a number?
'(scale x y) where x and y are both number?-s
'(translate x y) where x and y are both number?-s
'(color r g b a) where r, g, b, and a are color-number?-s
'(texture i) where i is a (or/c (instanceof/c bitmap%) pict? image?)
'(push-matrix instr ...) where each instr is an instruction
'(begin instr ...) where each instr is an instruction