Math and values¶

Invisible point entities that store, calculate and compare numbers, so a score, a count or a price can steer the map without a script. They are wired like every entity. A number travels along a connection as the value of an output, like changed(value) or result(value), and an input with no parameter of its own receives it, see No parameter. A parameter typed into the connection wins over the value.

Whole numbers stay whole, 2 + 3 is 5 and not 5.0, and a number that arrives as text like 2.5 counts as a number. Anything that is not a number counts as text.

math_value¶

Stores one number or piece of text, the way a variable does. Buttons add to it, and changed tells the rest of the map what it is now. It fires changed only when the value differs from before.

• Inputs: set_value(value), add(amount) (1 by default), get_value, reset
• Outputs: value(value), changed(value)
• Keys: start_value 0, a number or text

add sums two numbers and appends when either one is text, so adding ! to hello gives hello!. get_value fires value with what is stored, for when something needs the number without waiting for a change. reset goes back to start_value. A set_value without a value keeps what is stored.

math_calc¶

Does one calculation on the number it receives and fires the answer. It keeps nothing, so the same input always gives the same answer. Chain several to work something out in steps.

• Inputs: calculate(value), a missing value counts as 0
• Outputs: result(value)
• Keys: operation add, operand 1

abs, negate, round, floor and ceil ignore operand. When there is no answer, like divide or modulo by 0 or the root of a negative number, nothing fires and Godot prints a warning once.

math_compare¶

Compares a stored value with compare_value and fires which side it landed on. on_not_equal fires next to on_less and on_greater, for when only a difference matters.

• Inputs: set_value(value), set_compare_value(value), compare, set_and_compare(value)
• Outputs: on_less, on_equal, on_not_equal, on_greater
• Keys: compare_value 0

set_value and set_compare_value only store, compare compares what is stored, and set_and_compare does both, so it is the input to wire to a changed(value) output. Numbers compare by value, and 10 is more than 9. Two pieces of text compare in dictionary order, with capital letters before small ones. Nearly equal decimals, like 0.1 + 0.2 and 0.3, count as equal.

Example: a score that opens a door¶

Three coin buttons and a lever open a vault door once at least three coins are in.

1. Place a math_value named score, a math_compare named enough with compare_value 3, and a logic_gate named door_gate with gate and.
2. Wire each coin button's pressed to score, input add. Each press adds 1.
3. Wire score's changed to enough, input set_and_compare. It passes the new score on.
4. Wire enough's on_less to door_gate, input set_a, parameter false. Wire on_equal and on_greater the same way with parameter true. The gate's a now says whether there are enough coins.
5. Wire the lever's pressed to door_gate, input toggle_b.
6. Wire door_gate's on_true to the door with input open, and on_false with input close.

The door opens when the third coin lands while the lever is pulled, or the other way round. Pulling the lever back or resetting the score closes it. To show the score, wire changed of score to a game_text with input set_text, or put a math_calc in between to show points instead of coins.

The logic playground map builds this hall, and adds a light lottery with logic_random and logic_case and a lamp switch with logic_flipflop. Open godot/demo/maps/logic_playground.tdm in the demo project, or read how it is made in examples/mcp/logic_playground.json.

{ "tool": "gameplay", "args": { "op": "place", "classname": "math_value", "origin": [-280, 40, 40],
  "properties": { "targetname": "score" },
  "outputs": [ { "output": "changed", "target": "enough", "input": "set_and_compare" } ] } }
{ "tool": "gameplay", "args": { "op": "place", "classname": "math_compare", "origin": [-280, 40, -40],
  "properties": { "targetname": "enough", "compare_value": "3" },
  "outputs": [ { "output": "on_greater", "target": "door_gate", "input": "set_a", "parameter": "true" } ] } }