Smooth camera and unit motion: display positions, camera target smoothing, pan speed setting

src/render3d.rs

@@ -26,11 +26,46 @@ pub struct Cam {
     pub yaw: f32,
     pub pitch: f32,
     pub zoom: f32, // visible world height in tiles (orthographic)
+    #[serde(skip, default = "zero_f32")]
+    pub rx: f32, // smoothed look-at target used by the screen (world x)
+    #[serde(skip, default = "zero_f32")]
+    pub rz: f32, // smoothed look-at target used by the screen (world z = map y)
+    #[serde(skip, default = "cam_uninit")]
+    pub render_init: bool,
+}
+
+fn zero_f32() -> f32 {
+    0.0
+}
+
+fn cam_uninit() -> bool {
+    false
 }
 
 impl Cam {
     pub fn new(tx: f32, tz: f32) -> Cam {
-        Cam { tx, tz, yaw: 0.785, pitch: 0.6155, zoom: 18.0 }
+        Cam { tx, tz, yaw: 0.785, pitch: 0.6155, zoom: 18.0, rx: tx, rz: tz, render_init: true }
+    }
+
+    pub fn snap(&mut self) {
+        self.rx = self.tx;
+        self.rz = self.tz;
+        self.render_init = true;
+    }
+
+    pub fn update_render(&mut self, dt: f32) {
+        if !self.render_init {
+            self.snap();
+            return;
+        }
+        let dist = (self.tx - self.rx).abs() + (self.tz - self.rz).abs();
+        if dist > self.zoom.max(1.0) {
+            self.snap();
+            return;
+        }
+        let k = (1.0 - (-28.0 * dt.max(0.0)).exp()).clamp(0.0, 1.0);
+        self.rx += (self.tx - self.rx) * k;
+        self.rz += (self.tz - self.rz) * k;
     }
 
     pub fn eye_dir(&self) -> Vec3 {
@@ -38,7 +73,7 @@ impl Cam {
     }
 
     fn target(&self) -> Vec3 {
-        vec3(self.tx, 0.0, self.tz)
+        vec3(self.rx, 0.0, self.rz)
     }
 
     pub fn camera(&self) -> Camera3D {
@@ -990,7 +1025,7 @@ impl R3d {
             if !e.alive || e.held || (player_only && e.hero) {
                 continue;
             }
-            let s = Cam::project(&m, vec3(e.x, 0.3, e.y));
+            let s = Cam::project(&m, vec3(e.disp_x, 0.3, e.disp_y));
             let d = s.distance(vec2(sx, sy));
             if d < bd {
                 bd = d;
@@ -1231,7 +1266,7 @@ impl R3d {
             if mirror {
                 std::mem::swap(&mut u0, &mut u1);
             }
-            let a = amb(e.x, e.y) * if sleeping || e.captive == 1 { 0.6 } else { 1.0 };
+            let a = amb(e.disp_x, e.disp_y) * if sleeping || e.captive == 1 { 0.6 } else { 1.0 };
             // spell looks: stone grey, plague green, see-through when invisible
             let alpha = if e.invis > 0.0 { 0.35 } else { 1.0 };
             let c = if white {
@@ -1247,7 +1282,7 @@ impl R3d {
             };
             // pulled towards the camera: unchanged on screen (orthographic), but walls behind
             // the unit no longer cut into the sprite
-            let base = vec3(e.x, bob, e.y) + toward * 0.45 + r * (lunge * fwd);
+            let base = vec3(e.disp_x, bob, e.disp_y) + toward * 0.45 + r * (lunge * fwd);
             let (sr, cr) = rot.sin_cos();
             let corner = |dx: f32, dy: f32| {
                 let (dx, dy) = (dx * sx, dy * sy);
@@ -1288,7 +1323,7 @@ impl R3d {
             }
             let big = matches!(e.kind, EK::Ogre | EK::Paladin | EK::Jailer | EK::Chainbreaker | EK::Wyrm | EK::Gargoyle | EK::Giant);
             let lift = if flies(e.kind) && !(matches!(e.job, Job::Sleep(_)) && !e.moving) { 0.45 } else { 0.0 };
-            let head = proj(vec3(e.x, lift + if big { 0.9 } else { 0.72 }, e.y));
+            let head = proj(vec3(e.disp_x, lift + if big { 0.9 } else { 0.72 }, e.disp_y));
             // bar width in block characters, depending on the zoom
             let cols = ((px_per_tile * 0.6 / cw) as usize).clamp(3, 8);
             if (e.hp < e.max_hp || e.hero) && e.captive == 0 {
@@ -1320,7 +1355,7 @@ impl R3d {
                 gfx.glyph(b'z', head.x + cw * 2.0, head.y - GH * S() - rise, S(), Color::new(0.8, 0.85, 1.0, 1.0 - k));
             }
             if e.carry > 0 {
-                let p = proj(vec3(e.x, 0.35, e.y));
+                let p = proj(vec3(e.disp_x, 0.35, e.disp_y));
                 gfx.glyph(0x0F, p.x + cw * 2.0, p.y - GH * small, small, Color::from_rgba(250, 210, 60, 255));
             }
         }
@@ -1385,7 +1420,7 @@ fn draw_gear_glow(g: &Game, cam: &Cam, t: f32) {
     for e in g.ents.iter().filter(|e| gear_shown(e) && e.level >= 9) {
         let w = sprite_size(e.kind);
         let lift = if flies(e.kind) { 0.45 } else { 0.0 };
-        let base = vec3(e.x, lift, e.y) + toward * 0.5;
+        let base = vec3(e.disp_x, lift, e.disp_y) + toward * 0.5;
         let c = if e.hero { Color::new(0.8, 0.9, 1.0, 0.8) } else { Color::new(1.0, 0.8, 0.3, 0.8) };
         let y = w * 1.12 + (t * 2.0 + e.anim).sin() * 0.02;
         for k in 0..8 {
@@ -1394,7 +1429,7 @@ fn draw_gear_glow(g: &Game, cam: &Cam, t: f32) {
             line3(base + vec3(a0.cos() * 0.12, y, a0.sin() * 0.12), base + vec3(a1.cos() * 0.12, y, a1.sin() * 0.12), 0.025, c);
         }
         if e.level >= 10 {
-            disc(vec3(e.x, floor_y(g, e.x, e.y) + 0.015, e.y), 0.42 + 0.03 * (t * 3.0).sin(), Color::new(c.r, c.g, c.b, 0.18), 16);
+            disc(vec3(e.disp_x, floor_y(g, e.disp_x, e.disp_y) + 0.015, e.disp_y), 0.42 + 0.03 * (t * 3.0).sin(), Color::new(c.r, c.g, c.b, 0.18), 16);
         }
     }
 }
@@ -2090,8 +2125,8 @@ fn draw_shadows(g: &Game) {
             continue;
         }
         let r = if matches!(e.kind, EK::Ogre | EK::Paladin | EK::Jailer | EK::Chainbreaker | EK::Giant) { 0.32 } else { 0.24 };
-        let fy = floor_y(g, e.x, e.y);
-        disc(vec3(e.x, fy + 0.012, e.y), r, Color::new(0.0, 0.0, 0.0, 0.4), 12);
+        let fy = floor_y(g, e.disp_x, e.disp_y);
+        disc(vec3(e.disp_x, fy + 0.012, e.disp_y), r, Color::new(0.0, 0.0, 0.0, 0.4), 12);
         let rc = if e.captive != 0 {
             Color::new(0.6, 0.6, 0.6, 0.6)
         } else if e.dwarf() {
@@ -2109,7 +2144,7 @@ fn draw_shadows(g: &Game) {
         } else {
             Color::new(0.95, 0.3, 0.35, 0.7)
         };
-        ring(vec3(e.x, fy + 0.02, e.y), r + 0.03, rc);
+        ring(vec3(e.disp_x, fy + 0.02, e.disp_y), r + 0.03, rc);
     }
 }
 
@@ -2190,7 +2225,7 @@ fn draw_traps_solid(g: &Game, t: f32) {
             }
             CARRIED => {
                 if let Some(e) = g.ents.iter().find(|e| e.id + 1 == tr.carrier) {
-                    trap_crate(vec3(e.x, 0.42, e.y));
+                    trap_crate(vec3(e.disp_x, 0.42, e.disp_y));
                 }
             }
             ARMED => {