1 files changed, 36 insertions, 0 deletions
diff --git a/src/sky.js b/src/sky.js
new file mode 100644
index 0000000..9f74aea
--- /dev/null
+++ b/src/sky.js
@@ -0,0 +1,36 @@
+import { Mesh, BackSide, SphereGeometry, ShaderMaterial, Color } from "three";
+
+const SKY_COLOR = 0x999999;
+const GROUND_COLOR = 0x242424;
+const SKY_SIZE = 40000;
+
+export function addSkyGradient(scene) {
+  const vertexShader = `
+      varying vec3 vWorldPosition;
+            void main() {
+                vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
+                vWorldPosition = worldPosition.xyz;
+                gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
+            }`;
+  const fragmentShader = `
+      uniform vec3 topColor;
+            uniform vec3 bottomColor;
+            varying vec3 vWorldPosition;
+            void main() {
+                float h = (normalize(vWorldPosition).y ) / 2.0 + 0.25;
+                gl_FragColor = vec4( mix( bottomColor, topColor, h ), 1.0 );
+            }`;
+  const uniforms = {
+    topColor: { value: new Color(SKY_COLOR) },
+    bottomColor: { value: new Color(GROUND_COLOR) },
+  };
+  const skyGeo = new SphereGeometry(SKY_SIZE, 32, 15);
+  const skyMat = new ShaderMaterial({
+    uniforms,
+    vertexShader,
+    fragmentShader,
+    side: BackSide,
+  });
+  const sky = new Mesh(skyGeo, skyMat);
+  scene.add(sky);
+}