From 32a5308b595811b5fc0ca32997cb42f95719e3ca Mon Sep 17 00:00:00 2001
From: Josh Gao <josh@jmgao.dev>
Date: Tue, 6 Aug 2019 22:35:29 -0700
Subject: [PATCH] Add support for custom deadzones.

---
 dhc/src/config.rs    | 14 +++++++++++++-
 dhc/src/input/mod.rs |  1 +
 dhc/src/lib.rs       | 25 +++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/dhc/src/config.rs b/dhc/src/config.rs
index 0e50b1a..e8a0102 100644
--- a/dhc/src/config.rs
+++ b/dhc/src/config.rs
@@ -7,7 +7,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::logger;
 
-#[derive(Serialize, Deserialize, Debug)]
+#[derive(Clone, Serialize, Deserialize, Debug)]
 pub struct Config {
   #[serde(default = "default_console")]
   pub console: bool,
@@ -20,6 +20,14 @@ pub struct Config {
 
   #[serde(default = "default_xinput_enabled")]
   pub xinput_enabled: bool,
+
+  pub deadzone: Option<DeadzoneConfig>,
+}
+
+#[derive(Clone, Serialize, Deserialize, Debug)]
+pub struct DeadzoneConfig {
+  pub enabled: bool,
+  pub threshold: f32,
 }
 
 fn default_console() -> bool {
@@ -45,6 +53,10 @@ impl Default for Config {
       log_level: default_log_level(),
       device_count: default_device_count(),
       xinput_enabled: default_xinput_enabled(),
+      deadzone: Some(DeadzoneConfig {
+        enabled: false,
+        threshold: 0.5,
+      }),
     }
   }
 }
diff --git a/dhc/src/input/mod.rs b/dhc/src/input/mod.rs
index 9c96c13..9ac52a5 100644
--- a/dhc/src/input/mod.rs
+++ b/dhc/src/input/mod.rs
@@ -136,6 +136,7 @@ impl RawInputDeviceState {
       }
     }
 
+    crate::mangle_inputs(&mut inputs);
     self.buffer.write(inputs);
   }
 }
diff --git a/dhc/src/lib.rs b/dhc/src/lib.rs
index 21ea62e..af12c9b 100644
--- a/dhc/src/lib.rs
+++ b/dhc/src/lib.rs
@@ -262,3 +262,28 @@ impl Context {
     state.update();
   }
 }
+
+pub(crate) fn mangle_inputs(inputs: &mut DeviceInputs) {
+  if let Some(deadzone_config) = &CONFIG.deadzone {
+    if deadzone_config.enabled {
+      for ref mut axis in &mut [&mut inputs.axis_left_stick_x, &mut inputs.axis_left_stick_y] {
+        let value = axis.get();
+        // For convenience, interpolate from [0, 1] to [-1, 1], perform the
+        // deadzone operations, and then interpolate back.
+        let (sign, magnitude) = if value > 0.5 {
+          (1.0, (value - 0.5) * 2.0)
+        } else {
+          (-1.0, (0.5 - value) * 2.0)
+        };
+
+        let magnitude = if magnitude > deadzone_config.threshold {
+          1.0
+        } else {
+          0.0
+        };
+
+        axis.set_value(0.5 + 0.5 * sign * magnitude);
+      }
+    }
+  }
+}