gui_capslock_camera_pan.lua

function widget:GetInfo()
    return {
        name    = "Capslock SmoothScroll",
        desc    = "Use capslock to pan camera in the direction of mouse cursor. Can set param in file to override speed.",
        author  = "Errrrrrr, [DE]LSR, original implementation by trepan",
        date    = "June 2023",
        version = "1.0",
        license = "GNU GPL, v2 or later",
        layer   = 1,
        enabled = true, 
        handler = true,
    }
end

-------------------------------------------------------------------------------------------------------------
-- New implementation by Errrrrrr
-- Updated features:
-- 1) Capslock is now the default key to activate the camera pan
-- 2) Hold down capslock to pan the camera in the direction of mouse cursor
-- 3) Camera pan speed is now customizable
-- 4) Camera pan speed is now affected by camera height (so that camera pan speed is the same at all heights)
-------------------------------------------------------------------------------------------------------------
local override_speed_factor = 0 --  set to 0 to disable override

local spGetCameraState   = Spring.GetCameraState
local spGetCameraVectors = Spring.GetCameraVectors
local spGetModKeyState   = Spring.GetModKeyState
local spGetMouseState    = Spring.GetMouseState
local spIsAboveMiniMap   = Spring.IsAboveMiniMap
local spSendCommands     = Spring.SendCommands
local spSetCameraState   = Spring.SetCameraState
local spSetMouseCursor   = Spring.SetMouseCursor
local spWarpMouse        = Spring.WarpMouse

local blockModeSwitching = true


local vsx, vsy = widgetHandler:GetViewSizes()
function widget:ViewResize(viewSizeX, viewSizeY)
    vsx = viewSizeX
    vsy = viewSizeY
end

local mx, my
local active = false
local drawing = false

function widget:Update(dt)
    if (active) then
        local speedFactor = Spring.GetConfigInt('OverheadScrollSpeed', 10)
        if override_speed_factor > 0 then
            speedFactor = override_speed_factor
        end
        local x, y, lmb, mmb, rmb = spGetMouseState()
        local cs = spGetCameraState()
        local speed = dt * speedFactor

        local curHeight = minHeight

        if (cs.name == "ta") then
            curHeight = cs.height
        elseif (cs.name == "spring") then
            curHeight = cs.dist
        end
        speed = speed * (curHeight / 10000)

        if (cs.name == 'free') then
            local a, c, m, s = spGetModKeyState()
            if (c) then
                return
            end
            -- clear the velocities
            cs.vx  = 0; cs.vy = 0; cs.vz = 0
            cs.avx = 0; cs.avy = 0; cs.avz = 0
        end
        if (cs.name == 'ta') then
            local flip = -cs.flipped
            -- simple, forward and right are locked
            cs.px = cs.px + (speed * flip * (x - mx))
            if (false) then
                cs.py = cs.py + (speed * flip * (my - y))
            else
                cs.pz = cs.pz + (speed * flip * (my - y))
            end
        else
            -- forward, up, right, top, bottom, left, right
            local camVecs = spGetCameraVectors()
            local cf = camVecs.forward
            local len = math.sqrt((cf[1] * cf[1]) + (cf[3] * cf[3]))
            local dfx = cf[1] / len
            local dfz = cf[3] / len
            local cr = camVecs.right
            local len = math.sqrt((cr[1] * cr[1]) + (cr[3] * cr[3]))
            local drx = cr[1] / len
            local drz = cr[3] / len
            local mxm = (speed * (x - mx))
            local mym = (speed * (y - my))
            cs.px = cs.px + (mxm * drx) + (mym * dfx)
            cs.pz = cs.pz + (mxm * drz) + (mym * dfz)
        end

        spSetCameraState(cs, 0)

        if (mmb) then
            spSetMouseCursor('none')
        end
    end
end

function widget:KeyPress(key, mods, isRepeat)
    if key ~= 301 or isRepeat then return end
    
    local cs = spGetCameraState()
    if (blockModeSwitching and (cs.name ~= 'ta') and (cs.name ~= 'spring')) then
        local a, c, m, s = spGetModKeyState()
        return (c or s) --  block the mode toggling
    end
    if (cs.name == 'free') then
        local a, c, m, s = spGetModKeyState()   
        if (m and (not (c or s))) then
            return false
        end
    end
    active = not active
    if (active) then
        mx = vsx * 0.5
        my = vsy * 0.5
        spWarpMouse(mx, my)
        spSendCommands({ 'trackoff' })
    end
    return true
end

function widget:KeyRelease(key, mods, isRepeat)
    if key ~= 301 then return end

    active = false
    return -1
end

-- Adjust the camera position when the user scrolls the mouse wheel
function widget:MouseWheel(up, value)
    -- Get the current camera state and mod key state
    local cameraState = Spring.GetCameraState()
    local altDown, ctrlDown, metaDown, shiftDown = Spring.GetModKeyState()

    -- If the Alt key is down, adjust the camera height
    if altDown then
        local absCameraY = math.abs(cameraState.py)
        local cameraYDelta = (absCameraY / 10) * (up and -1 or 1)

        local newCameraState = {
            py = absCameraY + cameraYDelta
        }

        Spring.SetCameraState(newCameraState, Spring.GetConfigFloat("CameraTransitionTime",1.0))
        return true
    end

    -- If the camera mode is not "free", do nothing
    if cameraState.name ~= 'free' then
        return false
    end

    -- Get the mouse position and position on ground
    local mouseX, mouseY = Spring.GetMouseState()
    local _, groundPos = Spring.TraceScreenRay(mouseX, mouseY, true)

    -- If there is no ground position, adjust the camera vertically
    if not groundPos then
        local cameraYDelta = value * 10
        Spring.SetCameraState({
            vy = cameraState.vy + cameraYDelta
        }, 0)
    else
        -- Otherwise, adjust the camera position based on the ground position
        local dx = groundPos[1] - cameraState.px
        local dy = groundPos[2] - cameraState.py
        local dz = groundPos[3] - cameraState.pz
        -- local distance = math.sqrt((dx * dx) + (dy * dy) + (dz * dz))
        local speed = (up and 1 or -1) * (1 / 8)

        dx = dx * speed
        dy = dy * speed
        dz = dz * speed

        local newCameraState = {
            px = cameraState.px + dx,
            py = cameraState.py + dy,
            pz = cameraState.pz + dz,
            vx = 0,
            vy = 0,
            vz = 0
        }

        Spring.SetCameraState(newCameraState, Spring.GetConfigFloat("CameraTransitionTime",1.0))
    end

    return true
end