Define EPSILON, since it seems not to be defined by default on all systems. Fixes #48

BlueMapCore/src/main/webroot/js/libs/shaders/HiresVertexShader.js

@@ -25,6 +25,7 @@
 import { ShaderChunk } from 'three';
 
 const HIRES_VERTEX_SHADER = `
+#define EPSILON 1e-6
 ${ShaderChunk.logdepthbuf_pars_vertex}
 
 attribute float ao;

BlueMapCore/src/main/webroot/js/libs/shaders/LowresVertexShader.js

@@ -25,6 +25,7 @@
 import { ShaderChunk } from 'three';
 
 const LOWRES_VERTEX_SHADER = `
+#define EPSILON 1e-6
 ${ShaderChunk.logdepthbuf_pars_vertex}
 
 varying vec3 vPosition;