Implemented Rlights

Ported functionality of rlights.h into Rlights.cs, based on API cues in shaders_basic_lighting.cs from Raylib-cs-examples.
Most significant differences from Raylib's API are
- MAX_LIGHTS is a static field in the Rlights class
- CreateLight returns the Light struct instead of void

Raylib-cs/Rlights.cs

@@ -0,0 +1,94 @@
+using System;
+using static Raylib_cs.Raylib;
+using static Raylib_cs.ShaderUniformDataType;
+using System.Runtime.InteropServices;
+
+namespace Raylib_cs
+{
+    public static class Rlights
+    {
+        public static int MAX_LIGHTS = 4;
+        private static int lightsCount = 0;
+
+        public static Light CreateLight(LightType type, Vector3 pos, Vector3 targ, Color color, Shader shader)
+        {
+            Light light = new Light();
+
+            if (lightsCount < MAX_LIGHTS)
+            {
+                light.enabled = true;
+                light.type = type;
+                light.position = pos;
+                light.target = targ;
+                light.color = color;
+
+                string enabledName = "lights[" + lightsCount + "].enabled";
+                string typeName = "lights[" + lightsCount + "].type";
+                string posName = "lights[" + lightsCount + "].position";
+                string targetName = "lights[" + lightsCount + "].target";
+                string colorName = "lights[" + lightsCount + "].color";
+
+                light.enabledLoc = GetShaderLocation(shader, enabledName);
+                light.typeLoc = GetShaderLocation(shader, typeName);
+                light.posLoc = GetShaderLocation(shader, posName);
+                light.targetLoc = GetShaderLocation(shader, targetName);
+                light.colorLoc = GetShaderLocation(shader, colorName);
+
+                UpdateLightValues(shader, light);
+
+                //lights[lightsCount] = light;
+                lightsCount++;
+                return light;
+            }
+
+            return default;
+        }
+
+        public static void UpdateLightValues(Shader shader, Light light)
+        {
+            // Send to shader light enabled state and type
+            IntPtr enabledPtr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)));
+            Marshal.WriteInt32(enabledPtr, light.enabled ? ((Int32)1) : ((Int32)0));
+            SetShaderValue(shader, light.enabledLoc, enabledPtr, UNIFORM_INT);
+
+            IntPtr lightPtr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Int32)));
+            Marshal.WriteInt32(lightPtr, (Int32)light.type);
+            SetShaderValue(shader, light.typeLoc, lightPtr, UNIFORM_INT);
+
+            // Send to shader light position values
+            float[] position = new[] { light.position.x, light.position.y, light.position.z };
+
+            // Send to shader light target position values
+            float[] target = new[] { light.target.x, light.target.y, light.target.z };
+            IntPtr targetPtr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(float)) * target.Length);
+            Marshal.Copy(target, 0, targetPtr, target.Length);
+            SetShaderValue(shader, light.targetLoc, targetPtr, UNIFORM_VEC3);
+
+            // Send to shader light color values
+            float[] diff = new[] { (float)light.color.r / (float)255, (float)light.color.g / (float)255, (float)light.color.b / (float)255, (float)light.color.a / (float)255 };
+            IntPtr diffPtr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(float)) * diff.Length);
+            Marshal.Copy(diff, 0, diffPtr, diff.Length);
+            SetShaderValue(shader, light.colorLoc, diffPtr, UNIFORM_VEC4);
+        }
+    }
+
+    public enum LightType
+    {
+        LIGHT_DIRECTIONAL,
+        LIGHT_POINT
+    }
+
+    public struct Light
+    {
+        public bool enabled;
+        public LightType type;
+        public Vector3 position;
+        public Vector3 target;
+        public Color color;
+        public int enabledLoc;
+        public int typeLoc;
+        public int posLoc;
+        public int targetLoc;
+        public int colorLoc;
+    }
+}