- sdl_layer <-
texture: sdl_texture
|sdl_canvas* - What is shown: the pixels of a texture or what the layers of a canvas
draw. Nothing is shown if this is @nil.
- sdl_layer <-
source: area*
- Part of the texture that is shown, in pixels of the texture. @nil
shows the whole texture.
- sdl_layer <-
area: area*
- Where the texture is shown, in the coordinates of the window. @nil
uses the whole window. If sdl_layer
<-scale
is none, only the position is used.
- sdl_layer <-
scale: {stretch,fit,fill,none,tile}
- How the texture is fitted into sdl_layer
<-area. stretch
makes it exactly as large as the area; fit (default) makes
it as large as possible while keeping its aspect ratio and centres it; fill
covers the area while keeping the aspect ratio, cutting off what falls
outside;
none shows it at its own size with its hot spot at the
top-left corner of the area. The hot spot is
sdl_texture<-hot_spot
or else the top-left of the texture.
tile repeats the texture at its own size to fill the area,
starting at its top-left corner shifted by sdl_layer<-offset;
flipping, rotating and sdl_layer<-transform
apply to the whole tiled area. Tiles that are not rotated or flipped are
drawn in a single call by renderers that can repeat a texture, provided sdl_layer<-source
is @nil.
Otherwise each tile is drawn separately, so tiling a large area with a
small rotated texture is slow.
- sdl_layer <-
alpha:
- 0
.0..1.0 Opacity: 0.0
is invisible, 1.0 (default) is opaque.
- sdl_layer <-
angle: num
- Clockwise rotation in degrees around the hot spot of the texture or, if
it has none, around its centre.
- sdl_layer <-
flip: {none,horizontal,vertical,both}
- Mirror the texture.
horizontal shows a camera as in a
mirror.
- sdl_layer <-
transform: transform*
- If not @nil,
the placed texture is finally mapped through this affine transform, in
the coordinates of the window. This allows for any combination of
moving, rotating, scaling and shearing. Changing the transform
object itself is not noticed: send a (new) transform after changing it.
- sdl_layer <-
blend: {blend,add,mod,mul,none}
- How the texture is combined with what is below it, using the blend modes
of SDL.
blend (default) is normal alpha blending.
add adds the colours, which makes glows, light, fire and
particles. mod multiplies the colours below with those of
the texture, ignoring its transparency. mul does the same,
but keeps what is below where the texture is transparent, e.g.,
for shadows.
none replaces what is below by the texture, ignoring sdl_layer<-alpha
and transparency; it is only useful for opaque textures.
- sdl_layer <-
tint: colour*
- If not @nil,
the red, green and blue of the texture are multiplied by those of this
colour (SDL's color mod). A white texture thus shows in the tint
colour, which allows for one texture in many colours or to flash a
sprite. The alpha of the colour is ignored; use sdl_layer
<-alpha.
- sdl_layer <-
scale_mode: {linear,nearest,pixelart}
- How the pixels of a scaled or rotated texture are sampled.
linear (default) interpolates, which is smooth for photos
and video. nearest uses the nearest pixel, keeping sharp
pixel edges. pixelart (SDL 3.4
or later, otherwise nearest) also keeps the pixels sharp,
but avoids the uneven pixel sizes of
nearest at scales that are not whole numbers.
- sdl_layer <-
offset: point*
- Shift of the tiles if sdl_layer
<-scale
is tile, in pixels of the window.
@nil is the
same as point(0,0). Changing the offset scrolls the
pattern, e.g., for a scrolling background;
layers that share a texture can scroll at different speeds for a
parallax effect. As with sdl_layer<-area,
send a new point rather than changing it.
- sdl_layer <-
slices: area*
- If not @nil
and sdl_layer
<-scale
is stretch or tile, the texture is scaled as
nine parts (9-slice scaling), as is common for the frames of
buttons and panels. The area is the centre part, in pixels of the
texture; it is limited to sdl_layer<-source.
The four corners keep their size, the top and bottom edges only stretch
horizontally, the left and right edges only vertically and the centre in
both directions. Using tile, the edges and centre are
repeated instead of stretched. If sdl_layer<-area
is too small for the corners, they are shrunk. Other scales ignore the
slices. With
sdl_layer<-scale_mode linear,
a stretched part blends with the pixels of its neighbours at its border;
use nearest if this is a problem.
- sdl_layer <-
mesh: sdl_mesh*
- If not @nil,
the layer draws the triangles of this mesh instead of placing sdl_layer
<-texture
in sdl_layer<-area.
The texture is then mapped onto the triangles as their vertices say;
without a texture, the triangles show the colours of the vertices. See
class sdl_mesh.
- sdl_layer <-
displayed: bool
- If @off, the
layer is not shown.
- sdl_layer <-
device: sdl_window
|sdl_canvas* - The window or canvas showing the layer, as graphical
<-device
is the device showing a graphical. See sdl_window->append
and
sdl_canvas->append.
