Merge branch 'better-physics' into 'master'

FPS independent physics

See merge request veloren/veloren!168

common/src/sys/inputs.rs

@@ -17,6 +17,16 @@ use crate::{
 // Basic ECS AI agent system
 pub struct Sys;
 
+const HUMANOID_ACCEL: f32 = 100.0;
+const HUMANOID_SPEED: f32 = 500.0;
+const HUMANOID_AIR_ACCEL: f32 = 10.0;
+const HUMANOID_AIR_SPEED: f32 = 100.0;
+const HUMANOID_JUMP_ACCEL: f32 = 16.0;
+const GLIDE_ACCEL: f32 = 15.0;
+const GLIDE_SPEED: f32 = 45.0;
+// Gravity is 9.81 * 4, so this makes gravity equal to .15
+const GLIDE_ANTIGRAV: f32 = 9.81 * 3.95;
+
 impl<'a> System<'a> for Sys {
     type SystemData = (
         Entities<'a>,
@@ -73,51 +83,39 @@ impl<'a> System<'a> for Sys {
                 continue;
             }
 
-            // Handle held-down control
             let on_ground = terrain
                 .get((pos.0 - Vec3::unit_z() * 0.1).map(|e| e.floor() as i32))
                 .map(|vox| !vox.is_empty())
                 .unwrap_or(false)
                 && vel.0.z <= 0.0;
 
-            let (gliding, friction) = if on_ground {
-                // TODO: Don't hard-code this.
-                // Apply physics to the player: acceleration and non-linear deceleration.
-                vel.0 += Vec2::broadcast(dt.0) * control.move_dir * 200.0;
-
-                if jumps.get(entity).is_some() {
-                    vel.0.z += 16.0;
-                    jumps.remove(entity);
-                }
-
-                (false, 0.15)
+            let gliding = glides.get(entity).is_some() && vel.0.z < 0.0;
+            let move_dir = if control.move_dir.magnitude() > 1.0 {
+                control.move_dir.normalized()
             } else {
-                // TODO: Don't hard-code this.
-                // Apply physics to the player: acceleration and non-linear deceleration.
-                vel.0 += Vec2::broadcast(dt.0) * control.move_dir * 10.0;
-
-                if glides.get(entity).is_some() && vel.0.z < 0.0 {
-                    // TODO: Don't hard-code this.
-                    let anti_grav = 9.81 * 3.95 + vel.0.z.powf(2.0) * 0.2;
-                    vel.0.z +=
-                        dt.0 * anti_grav * Vec2::<f32>::from(vel.0 * 0.15).magnitude().min(1.0);
-
-                    (true, 0.008)
-                } else {
-                    (false, 0.015)
-                }
+                control.move_dir
             };
 
-            // Friction
-            vel.0 -= Vec2::broadcast(dt.0)
-                * 50.0
-                * vel.0.map(|e| {
-                    (e.abs() * friction * (vel.0.magnitude() * 0.1 + 0.5))
-                        .min(e.abs() * dt.0 * 50.0)
-                        .copysign(e)
-                })
-                * Vec3::new(1.0, 1.0, 0.0);
+            if on_ground {
+                // Move player according to move_dir
+                if vel.0.magnitude() < HUMANOID_SPEED {
+                    vel.0 += Vec2::broadcast(dt.0) * move_dir * HUMANOID_ACCEL;
+                }
 
+                // Jump
+                if jumps.get(entity).is_some() && vel.0.z <= 0.0 {
+                    vel.0.z = HUMANOID_JUMP_ACCEL;
+                    jumps.remove(entity);
+                }
+            } else if gliding && vel.0.magnitude() < GLIDE_SPEED {
+                let anti_grav = GLIDE_ANTIGRAV + vel.0.z.powf(2.0) * 0.2;
+                vel.0.z += dt.0 * anti_grav * Vec2::<f32>::from(vel.0 * 0.15).magnitude().min(1.0);
+                vel.0 += Vec2::broadcast(dt.0) * move_dir * GLIDE_ACCEL;
+            } else if vel.0.magnitude() < HUMANOID_AIR_SPEED {
+                vel.0 += Vec2::broadcast(dt.0) * move_dir * HUMANOID_AIR_ACCEL;
+            }
+
+            // Set direction based on velocity
             if vel.0.magnitude_squared() != 0.0 {
                 ori.0 = vel.0.normalized() * Vec3::new(1.0, 1.0, 0.0);
             }

common/src/sys/phys.rs

@@ -14,6 +14,29 @@ use vek::*;
 pub struct Sys;
 
 const GRAVITY: f32 = 9.81 * 4.0;
+const FRIC_GROUND: f32 = 0.15;
+const FRIC_AIR: f32 = 0.015;
+
+// Integrates forces, calculates the new velocity based off of the old velocity
+// dt = delta time
+// lv = linear velocity
+// damp = linear damping
+// Friction is a type of damping.
+fn integrate_forces(dt: f32, mut lv: Vec3<f32>, damp: f32) -> Vec3<f32> {
+    lv.z -= (GRAVITY * dt).max(-50.0);
+
+    let mut linear_damp = 1.0 - dt * damp;
+
+    if linear_damp < 0.0
+    // reached zero in the given time
+    {
+        linear_damp = 0.0;
+    }
+
+    lv *= linear_damp;
+
+    lv
+}
 
 impl<'a> System<'a> for Sys {
     type SystemData = (
@@ -31,18 +54,19 @@ impl<'a> System<'a> for Sys {
                 continue;
             }
 
-            // Gravity
-            vel.0.z = (vel.0.z - GRAVITY * dt.0).max(-50.0);
+            let on_ground = terrain
+                .get((pos.0 - Vec3::unit_z() * 0.1).map(|e| e.floor() as i32))
+                .map(|vox| !vox.is_empty())
+                .unwrap_or(false)
+                && vel.0.z <= 0.0;
 
             // Movement
             pos.0 += vel.0 * dt.0;
 
-            // Don't fall into the void.
-            // TODO: This shouldn't be needed when we have proper physics and chunk loading.
-            if pos.0.z < 0.0 {
-                pos.0.z = 0.0;
-                vel.0.z = 0.0;
-            }
+            // Integrate forces
+            // Friction is assumed to be a constant dependent on location
+            let friction = 50.0 * if on_ground { FRIC_GROUND } else { FRIC_AIR };
+            vel.0 = integrate_forces(dt.0, vel.0, friction);
 
             // Basic collision with terrain
             let mut i = 0.0;