Create/Update assets for version 21w20a

assets/minecraft/shaders/include/projection.glsl

@@ -0,0 +1,8 @@
+#version 150
+
+vec4 projection_from_position(vec4 position) {
+    vec4 projection = position * 0.5;
+    projection.xy = vec2(projection.x + projection.w, projection.y + projection.w);
+    projection.zw = position.zw;
+    return projection;
+}