Split perspective state out, to let shaders better interact with it

src/main/java/org/dynmap/hdmap/HDPerspectiveState.java

@@ -0,0 +1,46 @@
+package org.dynmap.hdmap;
+
+import org.dynmap.utils.Vector3D;
+
+public interface HDPerspectiveState {
+    /**
+     * Get sky light level - only available if shader requested it
+     */
+    int getSkyLightLevel();
+    /**
+     * Get emitted light level - only available if shader requested it
+     */
+    int getEmittedLightLevel();
+    /**
+     * Get current block type ID
+     */
+    int getBlockTypeID();
+    /**
+     * Get current block data
+     */
+    int getBlockData();
+    /**
+     * Get direction of last block step
+     */
+    HDMap.BlockStep getLastBlockStep();
+    /**
+     * Get perspective scale
+     */
+    double getScale();
+    /**
+     * Get start of current ray, in world coordinates
+     */
+    Vector3D getRayStart();
+    /**
+     * Get end of current ray, in world coordinates
+     */
+    Vector3D getRayEnd();
+    /**
+     * Get pixel X coordinate
+     */
+    int getPixelX();
+    /**
+     * Get pixel Y coordinate
+     */
+    int getPixelY();
+}