Remains of the dead in one mesh: drawing stays fast with hundreds of them

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/render3d.rs

@@ -1767,44 +1767,68 @@ impl R3d {
     // a broken blade; machines, stone and clockwork: splinters and rubble instead of blood);
     // dust puffs where a body hits the ground
     fn draw_remains(&self, g: &Game) {
+        // all remains in one mesh (hundreds of them would cost hundreds of draw calls):
+        // boxes on the floor with the colour of their stuff, seen from above and the sides
+        // (several meshes: one holds at most 65536 corners)
+        let mut meshes: Vec<MB> = vec![MB::new()];
+        let mut put = |lo: Vec3, hi: Vec3, c: [u8; 4]| {
+            if meshes.last().map_or(0, |m| m.v.len()) > 60000 {
+                meshes.push(MB::new());
+            }
+            let mb = meshes.last_mut().unwrap();
+            let (x0, y0, z0, x1, y1, z1) = (lo.x, lo.y, lo.z, hi.x, hi.y, hi.z);
+            let dark = [(c[0] as f32 * 0.7) as u8, (c[1] as f32 * 0.7) as u8, (c[2] as f32 * 0.7) as u8, 255];
+            let uv = [Vec2::ZERO; 4];
+            mb.quad([vec3(x0, y1, z0), vec3(x1, y1, z0), vec3(x1, y1, z1), vec3(x0, y1, z1)], uv, [c; 4], [Vec3::Y; 4]);
+            mb.quad([vec3(x0, y0, z1), vec3(x1, y0, z1), vec3(x1, y1, z1), vec3(x0, y1, z1)], uv, [dark; 4], [Vec3::Z; 4]);
+            mb.quad([vec3(x1, y0, z0), vec3(x1, y0, z1), vec3(x1, y1, z1), vec3(x1, y1, z0)], uv, [dark; 4], [Vec3::X; 4]);
+            mb.quad([vec3(x0, y0, z0), vec3(x1, y0, z0), vec3(x1, y1, z0), vec3(x0, y1, z0)], uv, [dark; 4], [-Vec3::Z; 4]);
+            mb.quad([vec3(x0, y0, z0), vec3(x0, y0, z1), vec3(x0, y1, z1), vec3(x0, y1, z0)], uv, [dark; 4], [-Vec3::X; 4]);
+        };
+        let at = |p: Vec3, s: Vec3| (p - s * 0.5, p + s * 0.5);
         for &(x, z, since, kind, seed) in &self.remains {
             let age = g.time - since;
             if age < 0.0 || !g.map.shown(idx(x as i32, z as i32)) {
                 continue;
             }
             let hero = crate::gfx::is_hero_kind(kind);
-            let sink = 0.0;
             let lifeless = matches!(kind, EK::Ram | EK::Catapult | EK::Gargoyle | EK::Cogling);
-            let off0 = |k: u32| ((((seed.wrapping_mul(2654435761) ^ k.wrapping_mul(40503)) >> 7) % 1000) as f32 / 1000.0 - 0.5) * 0.4;
+            let off = |k: u32| ((((seed.wrapping_mul(2654435761) ^ k.wrapping_mul(40503)) >> 7) % 1000) as f32 / 1000.0 - 0.5) * 0.4;
             if lifeless {
-                let wood = if matches!(kind, EK::Ram | EK::Catapult) { Color::from_rgba(110, 76, 44, 255) } else { Color::from_rgba(96, 94, 100, 255) };
+                let c = if matches!(kind, EK::Ram | EK::Catapult) { [110, 76, 44, 255] } else { [96, 94, 100, 255] };
                 for k in 0..5u32 {
-                    crate::props::auto_cube(vec3(x + off0(k + 20) * 1.2, 0.02, z + off0(k + 30) * 1.2), vec3(0.09, 0.04, 0.05 + (k % 2) as f32 * 0.08), wood);
+                    let (lo, hi) = at(vec3(x + off(k + 20) * 1.2, 0.02, z + off(k + 30) * 1.2), vec3(0.09, 0.04, 0.05 + (k % 2) as f32 * 0.08));
+                    put(lo, hi, c);
                 }
                 continue;
             }
             // the pool of blood, spread a little in the first seconds
             let spread = (age / 2.0).min(1.0);
             for k in 0..4u32 {
-                let r = (0.12 + off0(k + 40).abs() * 0.4) * (0.5 + 0.5 * spread);
+                let r = (0.12 + off(k + 40).abs() * 0.4) * (0.5 + 0.5 * spread);
-                draw_cube(vec3(x + off0(k + 50) * 0.6, 0.006 + k as f32 * 0.001, z + off0(k + 60) * 0.6), vec3(r, 0.004, r * 0.8), None, Color::from_rgba(92, 10, 14, 255));
+                let (lo, hi) = at(vec3(x + off(k + 50) * 0.6, 0.006 + k as f32 * 0.001, z + off(k + 60) * 0.6), vec3(r, 0.004, r * 0.8));
+                put(lo, hi, [92, 10, 14, 255]);
             }
-            let off = off0;
+            let bone = [214, 204, 182, 255];
-            let bone = Color::from_rgba(214, 204, 182, 255);
+            let iron = [120, 122, 132, 255];
-            let iron = Color::from_rgba(120, 122, 132, 255);
             for k in 0..3u32 {
-                let p = vec3(x + off(k * 2), 0.02 - sink, z + off(k * 2 + 1));
+                let p = vec3(x + off(k * 2), 0.02, z + off(k * 2 + 1));
-                if k % 2 == 0 {
+                let (lo, hi) = at(p, if k % 2 == 0 { vec3(0.16, 0.03, 0.03) } else { vec3(0.03, 0.03, 0.14) });
-                    crate::props::auto_cube(p, vec3(0.16, 0.03, 0.03), bone);
+                put(lo, hi, bone);
-                } else {
-                    crate::props::auto_cube(p, vec3(0.03, 0.03, 0.14), bone);
-                }
             }
             if hero {
-                crate::props::auto_cube(vec3(x + off(7), 0.04 - sink, z + off(8)), vec3(0.1, 0.07, 0.1), iron);
+                let (lo, hi) = at(vec3(x + off(7), 0.04, z + off(8)), vec3(0.1, 0.07, 0.1));
-                crate::props::auto_cube(vec3(x + off(9), 0.015 - sink, z + off(10)), vec3(0.2, 0.02, 0.03), iron);
+                put(lo, hi, iron);
+                let (lo, hi) = at(vec3(x + off(9), 0.015, z + off(10)), vec3(0.2, 0.02, 0.03));
+                put(lo, hi, iron);
             } else {
-                crate::props::auto_cube(vec3(x + off(7), 0.04 - sink, z + off(8)), vec3(0.08, 0.07, 0.08), bone);
+                let (lo, hi) = at(vec3(x + off(7), 0.04, z + off(8)), vec3(0.08, 0.07, 0.08));
+                put(lo, hi, bone);
+            }
+        }
+        for mb in meshes {
+            if let Some(m) = mb.into_plain_mesh() {
+                draw_mesh(&m);
             }
         }
         // dust where the dying hit the ground