Add Spring.GetProjectilesInSphere

[technateNG]

Fixes #1662.

[technateNG]

Tested with this.

function widget:GetInfo()
        return {
                name      = "My test widget",
                desc      = "Allows me to test stuff",
                author    = "dunno",
                date      = "Mar 12, 2023",
                license   = "GNU GPL, v2 or later",
                layer     = 0,
                enabled   = false
        }
end

local function tprint (tbl, indent)
  if not indent then indent = 0 end
  local toprint = string.rep(" ", indent) .. "{\r\n"
  indent = indent + 2 
  for k, v in pairs(tbl) do
    toprint = toprint .. string.rep(" ", indent)
    if (type(k) == "number") then
      toprint = toprint .. "[" .. k .. "] = "
    elseif (type(k) == "string") then
      toprint = toprint  .. k ..  "= "   
    end
    if (type(v) == "number") then
      toprint = toprint .. v .. ",\r\n"
    elseif (type(v) == "string") then
      toprint = toprint .. "\"" .. v .. "\",\r\n"
    elseif (type(v) == "table") then
      toprint = toprint .. tprint(v, indent + 2) .. ",\r\n"
    else
      toprint = toprint .. "\"" .. tostring(v) .. "\",\r\n"
    end
  end
  toprint = toprint .. string.rep(" ", indent-2) .. "}"
  return toprint
end


function widget:Initialize()
  local units = Spring.GetSelectedUnits()
  Spring.Echo(tprint(units))
  local x, y, z = Spring.GetUnitPosition(units[1])
  local radius = 100.5
  local radius_a = radius * math.sqrt(math.pi) / 2
  local xmin = x - radius_a
  local xmax = x + radius_a
  local zmin = z - radius_a
  local zmax = z + radius_a
  local a = Spring.GetProjectilesInRectangle(xmin, zmin, xmax, zmax)
  local b = Spring.GetProjectilesInSphere(x, y, z, radius)
  Spring.Echo(tprint(a))
  Spring.Echo(tprint(b))
end

Steps:

1. Run engine with BAR, map wathever
2. Enable cheats, create Bot Lab and make Pawn
3. Start shoot (by attack) towards Commander
4. Enable widget

Result: Both echoes shows the same.
I'll appreciate the ideas how to better test this kind of feature

[lhog]

Hmm I'm not sure the implementation is correct.
Why did you choose to ignore y coordinate and where is the actual check for projectile being inside the sphere?

[sprunk]

local a = Spring.GetProjectilesInRectangle(xmin, zmin, xmax, zmax)
local b = Spring.GetProjectilesInSphere(x, y, z, radius)
Spring.Echo(tprint(a))
Spring.Echo(tprint(b))

Test result: Both echoes shows the same.

That sounds incorrect because surely a sphere and a rectangle can't overlap perfectly.

Perhaps spawn some sort of 3D grid of lingering (speed=0 and gravity=0? whatever makes it easy to work with) projectiles, call GetProjectilesInSphere and delete anything that wasn't returned, and compare visually if the remaining projectiles form a sphere.

[sprunk]

I dislike these casts. Perhaps we should update the build process to enable some sort of "ignore warnings" flag for these?

[badosu]

Just a note, maybe the issue submitter meant a cylinder instead of a sphere. I commented on #1662 (comment) asking about this.

There might be use cases for sphere checking, e.g. custom proximity drawing/intercepting/shielding of projectiles, but the direct use required by the issue seems to be a circle cylinder.

In this scenario the check would be (pointA, pointB, radius) -> distinxzplane(pointA, pointB) < radius and the name Get*InCylinder in concordance to other similar calls. InSphere might still be desirable if you want to do it.

Edit: Motivation for use in a real game scenario indeed is Sphere, as commented here, feel free to proceed.

[technateNG]

Looks like this actually gets projectiles in a square inscribed into a circle rather than a sphere?

Hmm I'm not sure the implementation is correct.
Why did you choose to ignore y coordinate and where is the actual check for projectile being inside the sphere?

@lhog @sprunk Long story short I overthink it based on current usage.

[sprunk]

Looks alright