Vectors and Colors

Some values are made of several numbers. A color is four: red, green, blue and alpha. A vector is three, a point or a direction: x, y and z. A rotator is three angles: pitch, yaw and roll. This lesson builds them, takes them apart, and puts a color on a light.

Contents

• Code
• Run
• Under the Hood
• Taking values apart
• Modify
• Make
• Good to Know

switch1 Enabled -> chip red
switch2 Enabled -> chip green
switch3 Enabled -> chip blue
chip lamp -> light Color
chip lit -> light Enabled

Code

@left in red: bool
@left in green: bool
@left in blue: bool
@right out lamp = Color(red, green, blue)
@right out lit = red || green || blue

Color(r, g, b) makes a color from three numbers, each from 0 (none) to 1 (full). A fourth number, alpha, is optional. Here each channel comes from a switch: a bool is 1 when on and 0 when off, so each switch turns one channel fully on or off.

With the red and green switches on and blue off, what color is the light?

Run

1. Compile the chip and paste it in-game. Place three Switches and a Point Light. Turn off the light’s Use Brick Color setting: while it is on, the light takes the brick’s color and ignores the wire.
2. Wire each Switch’s Enabled to red, green and blue. Wire lamp to the Point Light’s Color and lit to its Enabled.
3. Try the switches. Red and green together make yellow, all three make white, and with all three off the light is off.

Under the Hood

Open the chip. Color(...) is one Make Color gate with the three pins wired into its R, G and B inputs. lit is two OR gates.

Taking values apart

Each part of a value has a name: .r .g .b .a on a color, .x .y .z on a vector, and .pitch .yaw .roll on a rotator. Each reads one float.

@left in pressed: exec
var spot: vector = Vec(0.0, 0.0, 0.0)
let step = Vec(1.0, 2.0, 0.5)
@right out text = "${spot.Value as string}, height ${spot.Value.z}"

on pressed {
  spot = spot + step
}

Vec(x, y, z) makes a vector. + on two vectors adds them part by part, so each press moves spot by 1 along x, 2 along y and 0.5 along z. spot.Value as string writes the whole vector as text, X=1.000 Y=2.000 Z=0.500 after the first press, and spot.Value.z reads just the height.

Reading a part is a Split Vector gate (or Split Color, Split Rotation). Reading several parts of the same value the same way (.x, .y, .z) shares one split gate.

Modify

1. Add a @left in dim: bool pin and dim the light while it is on: @right out lamp = if dim then Color(red, green, blue) * 0.25 else Color(red, green, blue). A number times a color multiplies every channel.

2. Pick a random color on each press. Random on two colors picks each channel at random between them:

   @left in pressed: exec
   var shade: color = Color(1.0, 1.0, 1.0)
   @right out lamp = shade.Value
   @right out text = shade.Value.ToHex()
   
   on pressed {
     shade = Random(Color(0.0, 0.0, 0.0), Color(1.0, 1.0, 1.0))
   }
   

   Like a variable write, Random runs as a step in a handler. .ToHex() turns a color into text, so a sign can show which color was picked.

3. Turn a rotator one eighth of a circle per press. Rotation(pitch, yaw, roll) takes angles in degrees:

   @left in pressed: exec
   var steps: int = 0
   let facing = Rotation(0.0, steps.Value * 45.0, 0.0)
   @right out aim = facing
   @right out text = "yaw ${facing.yaw}"
   
   on pressed {
     steps = (steps + 1) % 8
   }
   

   A Spot Light has a Rotation input that takes a rotator. Wire aim to it, and text to a Text Decal to watch the yaw count up by 45.

Make

Make a light that steps from blue to red. Each press moves it one step of five, and the sixth press starts again at blue. Keep a step count with %, and mix the two colors with arithmetic: Color(1.0, 0.0, 0.0) * t + Color(0.0, 0.0, 1.0) * (1.0 - t), where t is a float that goes from 0.0 (blue) to 1.0 (red).

button Held -> chip pressed
chip lamp -> light Color

Good to Know

• Color channels run from 0 to 1, not 0 to 255. ColorSRGB(255, 128, 0, 255) builds a color from 0 to 255 values instead.
• Random on two colors picks all four channels at random, alpha included.
• Asking a value for a part it does not have, such as .z on a color, is a compile error, never a silent zero.

Next: Converting Values.