Explicitly define precision for all variables, fall back to medium precision

osu.Game.Resources/Shaders/sh_CircularFlashlight.fs

@@ -1,10 +1,10 @@
 #include "sh_Flashlight.h"
 
 // highp precision is necessary for vertex positions to prevent catastrophic failure on GL_ES platforms
-vec4 getColourAt(highp vec2 diff, highp vec2 size, lowp vec4 originalColour)
+lowp vec4 getColourAt(highp vec2 diff, highp vec2 size, lowp vec4 originalColour)
 {
-    float dist = length(diff);
-    float flashlightRadius = length(size);
+    highp float dist = length(diff);
+    highp float flashlightRadius = length(size);
 
     return originalColour * vec4(1.0, 1.0, 1.0, smoothstep(flashlightRadius, flashlightRadius * smoothness, dist));
 }

osu.Game.Resources/Shaders/sh_Flashlight.h

@@ -1,5 +1,9 @@
 #ifdef GL_ES
     precision mediump float;
+    // Not all GPUs support high precision, so we should fall back to medium precision.
+    #ifndef GL_FRAGMENT_PRECISION_HIGH
+        #define highp
+    #endif
 #else
     // Since glsl 1.1 doesn't define precision qualifiers but GL_ES does, 
     // Define them as nothing to avoid compilation issues.
@@ -7,17 +11,20 @@
     #define highp
 #endif
 
-varying vec2 v_Position;
-varying vec4 v_Colour;
 
-uniform vec2 flashlightPos;
-uniform vec2 flashlightSize;
 
-uniform float flashlightDim;
+
+varying highp vec2 v_Position;
+varying lowp vec4 v_Colour;
+
+uniform highp vec2 flashlightPos;
+uniform highp vec2 flashlightSize;
+
+uniform lowp float flashlightDim;
 
 const float smoothness = 1.1;
 
-vec4 getColourAt(vec2, vec2, vec4);
+lowp vec4 getColourAt(vec2, vec2, vec4);
 
 void main(void)
 {