diff --git a/Metaballs/Renderer.swift b/Metaballs/Renderer.swift
index 62cb6a3..fbf9768 100644
--- a/Metaballs/Renderer.swift
+++ b/Metaballs/Renderer.swift
@@ -15,7 +15,7 @@ enum RendererError: Error {
 }
 
 protocol RendererDelegate {
-    var renderSize: CGSize { get set }
+    var renderSize: Size { get set }
     var field: Field { get }
     var metalView: MTKView { get }
 }
@@ -68,7 +68,7 @@ class Renderer: NSObject, MTKViewDelegate {
     /// MARK: - MTKViewDelegate
 
     func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {
-        delegate.renderSize = size
+        delegate.renderSize = Size(size: size)
     }
 
     func draw(in view: MTKView) {
diff --git a/Metaballs/Shaders.metal b/Metaballs/Shaders.metal
index 0b4f4c0..ecbee29 100644
--- a/Metaballs/Shaders.metal
+++ b/Metaballs/Shaders.metal
@@ -24,7 +24,11 @@ typedef struct {
     float2 textureCoordinate;
 } RasterizerData;
 
-typedef int3 Parameters;
+typedef struct {
+    short2 size;
+    ushort numberOfBalls;
+} Parameters;
+
 typedef float3 Ball;
 
 vertex RasterizerData
@@ -45,8 +49,7 @@ sampleToColorShader(RasterizerData in               [[stage_in]],
                     constant Parameters& parameters [[buffer(0)]],
                     constant Ball* balls            [[buffer(1)]])
 {
-    const uint numberOfBalls = parameters.z;
-    const float sample = sampleAtPoint(in.position.xy, balls, numberOfBalls);
+    const float sample = sampleAtPoint(in.position.xy, balls, parameters.numberOfBalls);
 
     const float target = 1.0;
 //    const float variange = 0.08;
@@ -56,7 +59,7 @@ sampleToColorShader(RasterizerData in               [[stage_in]],
     if (sample > target) {
         const float3 left = float3(0.50, 0.79, 1.00);
         const float3 right = float3(0.88, 0.50, 1.00);
-        const float blend = in.position.x / parameters.x;
+        const float blend = in.position.x / parameters.size.x;
         const float invBlend = 1.0 - blend;
         out = float4((blend * left.x + invBlend * right.x) / 2.0, (blend * left.y + invBlend * right.y) / 2.0, (blend * left.z + invBlend * right.z) / 2.0, 1.0);
     } else {
diff --git a/Metaballs/ViewController.swift b/Metaballs/ViewController.swift
index 35521da..dfe07cf 100644
--- a/Metaballs/ViewController.swift
+++ b/Metaballs/ViewController.swift
@@ -11,9 +11,9 @@ import MetalKit
 import MetaballsKit
 
 class ViewController: NSViewController, RendererDelegate {
-    internal var field = Field(size: CGSize()) {
+    internal var field = Field(size: Size()) {
         didSet {
-            field.size = metalView.drawableSize
+            field.size = Size(size: metalView.drawableSize)
         }
     }
 
@@ -73,7 +73,7 @@ class ViewController: NSViewController, RendererDelegate {
 
     // MARK: - RendererDelegate
 
-    var renderSize: CGSize {
+    var renderSize: Size {
         get {
             return field.size
         }