[1.1.76] What is the blending mode for LuaRendering color?
Posted: Sun Jan 22, 2023 11:21 am
Expectation: Rendering's color to behave like tint, and the default blendmode to be: normal.
Here is code used to draw squares (more complicated than it needs to be, I know), and something must be selected:
Results for alpha 1, which is full opacity (which the wiki still lists as transparency):
The result is sensible: alpha is fully opaque and draws 100% over the initial color.
Result = Active_RGB * Active_Alpha + Background_RGB * ( 1 - Active_Alpha )
Active Alpha 1:
Result = Active_RGB
Now, alpha force 0:
The result makes no sense. Alpha 0 is fully transparent for tinting, and
Result = Active_RGB * Active_Alpha + Background_RGB * ( 1 - Active_Alpha )
Clearly results in:
Result = Background_RGB
The non-forced code, where whiteness increases from left to right, and alpha increases from top to bottom:
This is clear that *just* changing the color results in an increase in opacity, the more white the color is. This is not the same blendmode as normal.
Here is code used to draw squares (more complicated than it needs to be, I know), and something must be selected:
Code: Select all
/c
local player = game.player
local surface = player.surface
local selected = player.selected
local position = selected.position
local X0 = position.x
local Y0 = position.y
local leftmost = -10
local rightmost = 10
local top = -10
local bottom = 10
--[[these aren't 100% accurate]]
local square_size = .5 --[[size of square relative to tile]]
local frequency = 1 --[[ at most 1]]
local occupancy = 1 --[[how much of the square is taken up]]
local period = square_size / frequency
local width_half = occupancy * square_size / 2
local height_half = occupancy * square_size / 2
local DX = (rightmost - leftmost)
local DY = (bottom - top)
for dy = top, bottom, period do
for dx = leftmost, rightmost, period do
local a = (dx - leftmost) / DX
local w = (dy - top) / DY
local force_a = true
if force_a then
a = 1
end
rendering.draw_rectangle{
color = {w, w, w, a},
filled = true,
left_top = {X0 - width_half + dx, Y0 - height_half + dy},
right_bottom = {X0 + width_half + dx, Y0 + height_half + dy},
surface = surface,
time_to_live = 180,
}
end
end- alpha_forced_1.png (342.45 KiB) Viewed 792 times
Result = Active_RGB * Active_Alpha + Background_RGB * ( 1 - Active_Alpha )
Active Alpha 1:
Result = Active_RGB
Now, alpha force 0:
- alpha_forced_0.png (403.55 KiB) Viewed 792 times
Result = Active_RGB * Active_Alpha + Background_RGB * ( 1 - Active_Alpha )
Clearly results in:
Result = Background_RGB
The non-forced code, where whiteness increases from left to right, and alpha increases from top to bottom:
- alpha_x_y.png (455.07 KiB) Viewed 792 times
