Implement fancy rendering for smart cables

Closes #107.

src/tools/render_passes/mod.rs

@@ -6,11 +6,13 @@ mod transit_tube;
 mod random;
 mod structures;
 mod icon_smoothing;
+mod smart_cables;
 
 pub use self::transit_tube::TransitTube;
 pub use self::random::Random;
 pub use self::structures::{GravityGen, Spawners};
 pub use self::icon_smoothing::IconSmoothing;
+pub use self::smart_cables::SmartCables;
 
 /// A map rendering pass.
 ///
@@ -102,6 +104,7 @@ pub const RENDER_PASSES: &[RenderPassInfo] = &[
     pass!(Pipes, "only-pipenet", "Render only atmospheric pipes.", false),
     pass!(FancyLayers, "fancy-layers", "Layer atoms according to in-game rules.", true),
     pass!(IconSmoothing, "icon-smoothing", "Emulate the icon smoothing subsystem.", true),
+    pass!(SmartCables, "smart-cables", "Handle smart cable layout.", true),
 ];
 
 pub fn configure(include: &str, exclude: &str) -> Vec<Box<dyn RenderPass>> {

src/tools/render_passes/smart_cables.rs

@@ -0,0 +1,98 @@
+use std::fmt::Write;
+use dmi::Dir;
+use super::*;
+
+#[derive(Default)]
+pub struct SmartCables;
+
+impl RenderPass for SmartCables {
+    fn neighborhood_appearance<'a>(&self,
+        atom: &Atom<'a>,
+        objtree: &'a ObjectTree,
+        neighborhood: &Neighborhood<'a, '_>,
+        output: &mut Vec<Sprite<'a>>,
+        bump: &'a bumpalo::Bump,
+    ) -> bool {
+        if !atom.istype("/obj/structure/cable/") {
+            return true;
+        }
+
+        let cable_layer = atom.get_var("cable_layer", objtree).as_str().unwrap_or("l2");
+
+        let mut under_smes = false;
+        let mut under_terminal = false;
+        for atom in neighborhood.center() {
+            if atom.istype("/obj/machinery/power/terminal/") {
+                under_terminal = true;
+            } else if atom.istype("/obj/machinery/power/smes/") {
+                under_smes = true;
+            }
+        }
+
+        // calculate linked dirs
+        let mut linked_dirs = 0;
+        'dir: for &check_dir in Dir::CARDINALS {
+            let turf = neighborhood.offset(check_dir);
+
+            // Don't link between SMES and terminal
+            if under_smes {
+                for atom in turf {
+                    if atom.istype("/obj/machinery/power/terminal/") {
+                        continue 'dir;
+                    }
+                }
+            } else if under_terminal {
+                for atom in turf {
+                    if atom.istype("/obj/machinery/power/smes/") {
+                        continue 'dir;
+                    }
+                }
+            }
+
+            for atom in turf {
+                if atom.istype("/obj/structure/cable/") {
+                    if atom.get_var("cable_layer", objtree).as_str().unwrap_or("l2") == cable_layer {
+                        linked_dirs |= check_dir.to_int();
+                        break;
+                    }
+                }
+            }
+        }
+
+        // calculate icon state
+        let mut icon_state;
+        if linked_dirs == 0 {
+            icon_state = bumpalo::format!(in bump, "{}-noconnection", cable_layer);
+        } else {
+            icon_state = bumpalo::format!(in bump, "{}", cable_layer);
+            let mut count = 0;
+            for &check_dir in Dir::CARDINALS {
+                if linked_dirs & check_dir.to_int() != 0 {
+                    let _ = write!(icon_state, "-{}", check_dir.to_int());
+                    count += 1;
+                }
+            }
+            if count > 1 && should_have_node(neighborhood.center()) {
+                let _ = write!(icon_state, "-node");
+            }
+        };
+
+        output.push(Sprite {
+            icon_state: icon_state.into_bump_str(),
+            .. atom.sprite
+        });
+        false
+    }
+}
+
+fn should_have_node(turf: &[Atom]) -> bool {
+    for atom in turf {
+        if atom.istype("/obj/structure/grille/") || atom.istype("/obj/structure/cable_bridge/") {
+            return true;
+        } else if atom.istype("/obj/machinery/power/") {
+            // TODO: more detailed type-specific checks
+            return true;
+        }
+    }
+    false
+}