Movedefs.lua

Movedefs.lua

Location

movedefs.lua is a file in the Gamedata/ directory of a Spring Game.

Purpose

This file defines MoveClasses which are used to determine pathing for units.

Source

The engine source code which parses the data from this file is viewable here: rts/Sim/MoveTypes/MoveInfo.cpp

Details

A mobile unit is assigned a MoveClass using the movementClass UnitDef tag. The engine determines the unit's pathfinding based on the properties of the MoveClass, so analogous properties (e.g. FootprintX) in the UnitDef should be the same for optimal behaviour.

All MoveClasses must belong to one of four possible types. A MoveClass is assigned a type simply by including it within the name string e.g. Tank_MyMoveClassName. Types are used in TypeMaps of Spring maps, which allow mappers to set per-type speed multipliers.

Types

• Bot - A ground based MoveClass. The default type if no matching type string is found.
• Tank - A ground based MoveClass. Identical to Bot other than interaction with TypeMaps.
• Ship or Boat - Are synonyms. All ships / boat MoveClasses must belong to this type to behave as ships.
• Hover - All hovercraft MoveClasses (traverse any depth of water without speed reduction) must belong to this class, as well as having canHover in their UnitDef to behave as hovers.

MoveClass Tags

string name  default: "" 

The name of the MoveClass. Usually passed by the sub-table variable name rather than using the name tag (See #Example). Must contain "tank", "hover", "ship" or "boat" respectively for non-Bot types.

int footprintX  default: 1 

How wide the MoveClass is in footprint units, left to right. 1 footprint unit = 16 elmos. Cannot be below 1. For mobile units this should be the same as the footprintX of its UnitDef.

int footprintZ  default: footprintX 

How wide the MoveClass is in footprint units, top to bottom. 1 footprint unit = 16 elmos. Cannot be below 1. For mobile units this should be the same as the footprintZ of its UnitDef.

float crushStrength  default: 10.0 

Power of a unit with this MoveClass to crush features and units. Any features (and units with crushing enabled via Spring.SetUnitBlocking) with a crushResistance less than this value will be crushed on contact (See Units-FeatureDefs#General and Units-UnitDefs#General).

float maxSlope  default: 60.0 (15.0 for hover types) 

The maximum steepness of slope a unit with this MoveClass can climb in degrees. For further details see #How_slope_is_determined.

float slopeMod  default: 4.0 / (maxSlope + 0.001) 

How much a slope will slow a unit, 0 means no slowdown.

Heat Tags

These tags are used in unit avoidance. bool heatMapping  default: false 

This enables/disables generation and usage of path heats.

float heatMod  default: 0.05 

The pathfinder cost modifier that is multiplied by the heat of the current square.

int heatProduced  default: 30 

How much heat to place on a square if a path goes through it. heat set = max(currentSquareHeat, heatProduced).

Tank & Bot-Only Tags

float depthMod  default: 0.1 

How much water will slow amphibious units. The deeper the water, the slower the movement.Replaced with a subtable in Spring 86.x

float maxWaterDepth  default: 0.0 

The maximum depth of water in elmos the unit can wade through.

depthModParams

Depthmod has been broken out into the depthModParams group. depthModParams group contains several sub-tags. Depthmod is a system for changing the speed of units depending on how deep they are underwater.

      new formula is given by
        if h < depthModParams.minHeight: 1.0
        if h > depthModParams.maxHeight: 0.0
        else:
          depthScale = MAX(0.01, MIN(depthModParams.maxScale, (a * h * h) + (b * h) + c))
          depthMod = 1 / depthScale
      where
        h = unit's absolute height below water surface
        a = depthModParams.quadraticCoeff
        b = depthModParams.linearCoeff
        c = depthModParams.constantCoeff

float minHeight  default: 0.0 

The minimum depth where the depthMod curve applies. If the unit is shallower than the minHeight, no change in speed occurs.

float maxHeight  default: MAX_FLOAT 

The maximum depth where the depthMod curve applies. If the unit is deeper than the maxHeight, the unit is immobilized.

The following tags control the behavior of the unit within the active portion of the curve (depth is greater than minHeight but less than maxHeight). It would be best to simply open up your graphing program of choice and use the provided formula, but if you're scared of graphs you should read the descriptions below:

float maxScale  default: MAX_FLOAT 

This is the cap on how severe the depth effect can be. That is, if maxscale is 2, the slowest the unit will go because of depth is half-speed. 4 = a quarter speed, and so on.

float quadraticCoeff  default: 0.0 

The application of the speed-divider effect is modeled as a quadratic. This is the "depth-squared" component of that. That is, a value set here will be applied exponentially as the unit gets deeper... use very small numbers for this one.

float linearCoeff  default: depthMod 

The application of the speed-divider effect is modeled as a quadratic. This component makes divisor increase linearly with the depth of the unit. So with a value of 0.1, for example, a unit would go from 1/2 speed to 1/3 speed and 1/3 speed to 1/4 speed each time it goes 10 units deeper.

float constantCoeff  default: 1.0 

The application of the speed-divider effect is modeled as a quadratic. This is the constant component of the divisor. If you want a gradual decrease of speed and your minHeight is 0 (the waterline) then this value *must* be 1. Using less than 1 will cause the unit to go *faster* as it hits the water, and using greater than 1 will cause the unit to abruptly slow down the moment it gets its feet wet. If you're not using a minHeight of 0, you'll have to adjust this value accordingly to get that same smooth application of the depthMod divider.

Ship-Only Tags

float minWaterDepth  default: 10.0 

The minimum depth of water in elmos the ship requires to float in.

bool subMarine  default: false 

Is the ship a submarine; can it move underneath other ships?

How slope is determined

Spring doesn't represent terrain slopes in degrees, internally it uses (1.0 - the terrain normal's y-component) so the slope of vertical faces is 1 and that of horizontal ones 0. A unit's maxSlope value (which is in degrees in its movedef) is converted so that the "can we go here?" (ie "maxSlope > terrainSlope?") comparisons are meaningful, the formula is 1.0 - cos(DEG2RAD(maxSlope * 1.5)). If you want to know the terrain angle in degrees, compute RAD2DEG(arccos(1.0 - terrainSlope)). For a bot with a maxSlope of 36 degrees (~0.41221 in "Spring format"), the maximum tolerable terrain angle is approximately

RAD2DEG(arccos(1.0 - 0.41221))

or 54 degrees. If maxSlope was 30, the MTTA would be 45, and if it was 60 (the highest sensible value due to that 1.5 scalar and the absence of overhanging cliffs) the bot could mount any terrain. In other words you do not need the long mathematical derivation, just remember that maxTerrainAngle = maxSlope * 1.5

--kloot, Thu Jul 31, 2008

Example

External Examples

'Balanced Annihilation' movedefs.lua

'Complete Annihilation' movedefs.lua

'Spring: 1944' movedefs.lua

'Spring Tutorial Game' movedefs.lua

'ZeroK' movedefs.lua