From e2d96cc7e0b14f9fb59782f58ae2590cafc07b74 Mon Sep 17 00:00:00 2001
From: Louis Pearson <desttinghimgame@gmail.com>
Date: Thu, 23 May 2019 08:03:21 -0600
Subject: [PATCH] Add CollisionShape, move friction calculations to phys

Former-commit-id: 3723a8f74bc2854aaa98357e2d0b51a1668d9030
---
 common/src/sys/inputs.rs | 61 +++++++++++++++++-----------------------
 common/src/sys/phys.rs   | 15 ++++++++++
 2 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/common/src/sys/inputs.rs b/common/src/sys/inputs.rs
index 7e1f1216ee..198b485cda 100644
--- a/common/src/sys/inputs.rs
+++ b/common/src/sys/inputs.rs
@@ -17,6 +17,14 @@ 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 = 25.0;
+const GLIDE_SPEED: f32 = 200.0;
+
 impl<'a> System<'a> for Sys {
     type SystemData = (
         Entities<'a>,
@@ -73,51 +81,34 @@ 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;
+            let gliding = glides.get(entity).is_some() && vel.0.z < 0.0;
 
-                if jumps.get(entity).is_some() {
-                    vel.0.z += 16.0;
+            if on_ground {
+                // Move player according to move_dir
+                if vel.0.magnitude() < HUMANOID_SPEED {
+                    vel.0 += Vec2::broadcast(dt.0) * control.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 = 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);
+                vel.0 += Vec2::broadcast(dt.0) * control.move_dir * GLIDE_ACCEL;
+            } else if vel.0.magnitude() < HUMANOID_AIR_SPEED {
+                vel.0 += Vec2::broadcast(dt.0) * control.move_dir * HUMANOID_AIR_ACCEL;
+            }
 
-                (false, 0.15)
-            } 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)
-                }
-            };
-
-            // 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);
-
+            // 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);
             }
diff --git a/common/src/sys/phys.rs b/common/src/sys/phys.rs
index 94a8f565b2..bafbe3e7c5 100644
--- a/common/src/sys/phys.rs
+++ b/common/src/sys/phys.rs
@@ -31,6 +31,21 @@ 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;
+
+            // Friction
+            // Will never make the character go backwards since it is interpolating towards 0
+            let friction = if on_ground { 0.15 } else { 0.015 };
+            let mul = 50.0;
+            let z = vel.0.z;
+            vel.0 = Vec3::lerp(vel.0, Vec3::new(0.0, 0.0, 0.0), friction * dt.0 * mul);
+            vel.0.z = z;
+
             // Gravity
             vel.0.z = (vel.0.z - GRAVITY * dt.0).max(-50.0);