Add HUD indicator for rotating on edges

hud.lua

@@ -1,37 +1,97 @@
-local nodecore
-    = nodecore
+local nodecore, vector, math_round
+    = nodecore, vector, math.round
+
+local TAU = math.pi * 2 -- The real circle constant.
+local QUARTER_CIRCLE = TAU / 4
 
 local LABEL_ROTATION_HINT = "rotation hint"
+local LABEL_AXIS_HINT     = "axis hint"
 
-local TEX_ROTATE_FACE = "nc_extended_rotating_hud_rotate_face.png"
-local TEX_ROTATE_EDGE = "nc_extended_rotating_hud_rotate_edge.png"
+local TEX_ROTATE_FACE   = "nc_extended_rotating_hud_rotate_face.png"
+local TEX_ROTATE_EDGE   = "nc_extended_rotating_hud_rotate_edge.png"
+local TEX_ROTATION_AXIS = "nc_extended_rotating_hud_rotation_axis.png"
 
 
 local hud = {}
 
 function hud.update_player_hud(player, state)
-    local function crosshair_hud_element(texture)
-        return {
-            label = LABEL_ROTATION_HINT,
+    local rotation_texture = nil
+    local axis_texture     = nil
+
+    local mode = state and state.mode
+    if mode == "face" then
+        local tex = TEX_ROTATE_FACE
+        if state.invert then tex = tex .. "^[transformFX" end
+        rotation_texture = tex
+
+    elseif mode == "edge" then
+        local tex = TEX_ROTATE_EDGE
+        if state.invert then tex = tex .. "^[transformFX" end
+
+        local face = state.face -- Face looked at.
+        local edge = state.edge -- Face, edge or corner looked at.
+        local axis = state.axis -- Actual axis of rotation.
+        local look = player:get_look_dir() -- Player look vector.
+
+        -- Transform a vertical face to an equivalent horizontal one,
+        -- to make the following comparisons work in either case.
+        if state.face.y ~= 0 then
+            local player_yaw     = math_round(player:get_look_horizontal() / QUARTER_CIRCLE) * QUARTER_CIRCLE
+            local playing_facing = vector.new(0, 0, 1):rotate_around_axis(vector.new(0, 1, 0), player_yaw)
+            local rotation_axis  = face:cross(playing_facing)
+
+            face = face:rotate_around_axis(rotation_axis, QUARTER_CIRCLE)
+            edge = edge:rotate_around_axis(rotation_axis, QUARTER_CIRCLE)
+            axis = axis:rotate_around_axis(rotation_axis, QUARTER_CIRCLE)
+            look = look:rotate_around_axis(rotation_axis, QUARTER_CIRCLE)
+        end
+
+        if edge.y == 0 then -- Looking at left or right edge.
+            if axis.y > 0
+                then tex = tex .. "^[transformFX"    -- left
+                else                                 -- right
+            end
+            -- Flip side the arrow is on depending on look vector.
+            if look.y < 0 then tex = tex .. "^[transformFY" end
+            -- Vertical axis rotation texture.
+            axis_texture = TEX_ROTATION_AXIS
+
+        else                -- Looking at top or bottom edge.
+            if edge.y > 0
+                then tex = tex .. "^[transformR90"   -- top
+                else tex = tex .. "^[transformFXR90" -- bottom
+            end
+            -- Flip side the arrow is on depending on look vector.
+            if face:cross(look).y < 0 then tex = tex .. "^[transformFX" end
+            -- Horizontal axis rotation texture.
+            axis_texture = TEX_ROTATION_AXIS .. "^[transformR270"
+        end
+
+        rotation_texture = tex
+
+    elseif mode == "corner" then
+        -- TODO: Handle corners.
+    end
+
+    local function crosshair_hud_element(label, texture)
+        if texture then return {
+            label = label,
             hud_elem_type = "image",
-            text = texture,
+            text = texture .. "^[opacity:" .. 192,
             position  = { x = 0.5, y = 0.5 },
             offset    = { x = 0, y = 0 },
             alignment = { x = 0, y = 0 },
             scale     = { x = 1, y = 1 },
-            quick = true
-        }
+            quick = true,
+        } else return {
+            label = label,
+            ttl   = 0,
+        } end
     end
 
-    local mode = state and state.mode
-    if mode == "face" then
-        local texture = TEX_ROTATE_FACE
-        if state.invert then texture = texture .. "^[transformFX" end
-        texture = texture .. "^[opacity:" .. 192
-        nodecore.hud_set(player, crosshair_hud_element(texture))
-    else
-        nodecore.hud_set(player, { label = LABEL_ROTATION_HINT, ttl = 0 })
-    end
+    -- Actually update the HUD elements.
+    nodecore.hud_set(player, crosshair_hud_element(LABEL_ROTATION_HINT, rotation_texture))
+    nodecore.hud_set(player, crosshair_hud_element(LABEL_AXIS_HINT, axis_texture))
 end
 
 return hud

init.lua

@@ -16,7 +16,8 @@ local update_rotating_state = nc_extended_rotating.state.update_rotating_state
 local get_rotating_state    = nc_extended_rotating.state.get_rotating_state
 
 -- TODO: Fix HUD showing rotation hint when we wouldn't / can't rotate.
--- TODO: Add crosshair indicators for rotating around edges.
+-- TODO: Add crosshair indicators for rotating around corners.
+-- TODO: Use Aux1 control to use NodeCore's built-in rotation?
 -- TODO: Add some more comments.
 -- TODO: Add particles to preview rotation?
 

state.lua

@@ -19,6 +19,16 @@ local rotating_state = {}
 -- This state contains information about how the player would rotate a block.
 local function calculate_rotating_state(player, data)
     local state = {}
+    -- {
+    --   pos     = position of the node to be rotated
+    --   node    = the node being rotated
+    --   face    = a vector pointing away from the face looked at
+    --   edge    = a vector pointing to the face, edge or corner looked at
+    --   axis    = calculated axis to rotate around
+    --   invert  = whether the rotation was inverted due to holding sneak
+    --   facedir = the facedir value to set the node to on rotation
+    --   success = whether rotating would be successful
+    -- }
 
     local pointed_thing = data.raycast()
     if (not pointed_thing) or pointed_thing.type ~= "node" then return nil end
@@ -36,6 +46,7 @@ local function calculate_rotating_state(player, data)
 
     local degrees = 90
     local r = rotation_vector_from_lookat(state.node, pointed_thing, EDGE_DISTANCE)
+    state.edge = r
     state.axis = r
 
     local num = math_round(r.x * r.x + r.y * r.y + r.z * r.z) -- Squared length.