Improve utils for mesh generation and processing (#199)

* Add memory allocation to Raylib.Utils for memory allocation (#179)
* Add utils to Mesh for allocating and accessing mesh attributes (#179)

Raylib-cs/types/Mesh.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Runtime.InteropServices;
 
 namespace Raylib_cs;
@@ -9,6 +10,15 @@ namespace Raylib_cs;
 [StructLayout(LayoutKind.Sequential)]
 public unsafe partial struct Mesh
 {
+    /// <summary>
+    ///  Creates a mesh ready for default vertex data allocation
+    /// </summary>
+    public Mesh(int vertexCount, int triangleCount)
+    {
+        VertexCount = vertexCount;
+        TriangleCount = triangleCount;
+    }
+
     /// <summary>
     ///  Number of vertices stored in arrays
     /// </summary>
@@ -24,37 +34,149 @@ public unsafe partial struct Mesh
     /// <summary>
     /// Vertex position (XYZ - 3 components per vertex) (shader-location = 0)
     /// </summary>
-    public float* Vertices;
+    public float* Vertices = default;
 
     /// <summary>
     /// Vertex texture coordinates (UV - 2 components per vertex) (shader-location = 1)
     /// </summary>
-    public float* TexCoords;
+    public float* TexCoords = default;
 
     /// <summary>
     /// Vertex second texture coordinates (useful for lightmaps) (shader-location = 5)
     /// </summary>
-    public float* TexCoords2;
+    public float* TexCoords2 = default;
 
     /// <summary>
     /// Vertex normals (XYZ - 3 components per vertex) (shader-location = 2)
     /// </summary>
-    public float* Normals;
+    public float* Normals = default;
 
     /// <summary>
     /// Vertex tangents (XYZW - 4 components per vertex) (shader-location = 4)
     /// </summary>
-    public float* Tangents;
+    public float* Tangents = default;
 
     /// <summary>
     /// Vertex colors (RGBA - 4 components per vertex) (shader-location = 3)
     /// </summary>
-    public byte* Colors;
+    public byte* Colors = default;
 
     /// <summary>
     /// Vertex indices (in case vertex data comes indexed)
     /// </summary>
-    public ushort* Indices;
+    public ushort* Indices = default;
+
+    /// <summary>
+    /// Allocate <see cref="Vertices"/>
+    /// </summary>
+    public void AllocVertices()
+    {
+        Vertices = Raylib.New<float>(3 * VertexCount);
+    }
+
+    /// <summary>
+    /// Allocate <see cref="TexCoords"/>
+    /// </summary>
+    public void AllocTexCoords()
+    {
+        TexCoords = Raylib.New<float>(2 * VertexCount);
+    }
+
+    /// <summary>
+    /// Allocate <see cref="TexCoords2"/>
+    /// </summary>
+    public void AllocTexCoords2()
+    {
+        TexCoords2 = Raylib.New<float>(2 * VertexCount);
+    }
+
+    /// <summary>
+    /// Allocate <see cref="Normals"/>
+    /// </summary>
+    public void AllocNormals()
+    {
+        Normals = Raylib.New<float>(3 * VertexCount);
+    }
+
+    /// <summary>
+    /// Allocate <see cref="Tangents"/>
+    /// </summary>
+    public void AllocTangents()
+    {
+        Tangents = Raylib.New<float>(4 * VertexCount);
+    }
+
+    /// <summary>
+    /// Allocate <see cref="Colors"/>
+    /// </summary>
+    public void AllocColors()
+    {
+        Colors = Raylib.New<byte>(4 * VertexCount);
+    }
+
+    /// <summary>
+    /// Allocate <see cref="Indices"/>
+    /// </summary>
+    public void AllocIndices()
+    {
+        Indices = Raylib.New<ushort>(3 * TriangleCount);
+    }
+
+    /// <summary>
+    /// Access <see cref="Vertices"/>
+    /// </summary>
+    public readonly Span<T> VerticesAs<T>() where T : unmanaged
+    {
+        return new(Vertices, 3 * VertexCount * sizeof(float) / sizeof(T));
+    }
+
+    /// <summary>
+    /// Access <see cref="TexCoords"/>
+    /// </summary>
+    public readonly Span<T> TexCoordsAs<T>() where T : unmanaged
+    {
+        return new(TexCoords, 2 * VertexCount * sizeof(float) / sizeof(T));
+    }
+
+    /// <summary>
+    /// Access <see cref="TexCoords2"/>
+    /// </summary>
+    public readonly Span<T> TexCoords2As<T>() where T : unmanaged
+    {
+        return new(TexCoords2, 2 * VertexCount * sizeof(float) / sizeof(T));
+    }
+
+    /// <summary>
+    /// Access <see cref="Normals"/>
+    /// </summary>
+    public readonly Span<T> NormalsAs<T>() where T : unmanaged
+    {
+        return new(Normals, 3 * VertexCount * sizeof(float) / sizeof(T));
+    }
+
+    /// <summary>
+    /// Access <see cref="Tangents"/>
+    /// </summary>
+    public readonly Span<T> TangentsAs<T>() where T : unmanaged
+    {
+        return new(Tangents, 4 * VertexCount * sizeof(float) / sizeof(T));
+    }
+
+    /// <summary>
+    /// Access <see cref="Colors"/>
+    /// </summary>
+    public readonly Span<T> ColorsAs<T>() where T : unmanaged
+    {
+        return new(Colors, 4 * VertexCount * sizeof(byte) / sizeof(T));
+    }
+
+    /// <summary>
+    /// Access <see cref="Indices"/>
+    /// </summary>
+    public readonly Span<T> IndicesAs<T>() where T : unmanaged
+    {
+        return new(Indices, 3 * TriangleCount * sizeof(ushort) / sizeof(T));
+    }
 
     #endregion
 
@@ -63,22 +185,22 @@ public unsafe partial struct Mesh
     /// <summary>
     /// Animated vertex positions (after bones transformations)
     /// </summary>
-    public float* AnimVertices;
+    public float* AnimVertices = default;
 
     /// <summary>
     /// Animated normals (after bones transformations)
     /// </summary>
-    public float* AnimNormals;
+    public float* AnimNormals = default;
 
     /// <summary>
     /// Vertex bone ids, up to 4 bones influence by vertex (skinning)
     /// </summary>
-    public byte* BoneIds;
+    public byte* BoneIds = default;
 
     /// <summary>
     /// Vertex bone weight, up to 4 bones influence by vertex (skinning)
     /// </summary>
-    public float* BoneWeights;
+    public float* BoneWeights = default;
 
     #endregion
 
@@ -87,12 +209,12 @@ public unsafe partial struct Mesh
     /// <summary>
     /// OpenGL Vertex Array Object id
     /// </summary>
-    public uint VaoId;
+    public uint VaoId = default;
 
     /// <summary>
     /// OpenGL Vertex Buffer Objects id (default vertex data, uint[])
     /// </summary>
-    public uint* VboId;
+    public uint* VboId = default;
 
     #endregion
 }

Raylib-cs/types/Raylib.Utils.cs

@@ -222,6 +222,12 @@ public static unsafe partial class Raylib
         }
     }
 
+    /// <summary>C++ style memory allocator</summary>
+    public static T* New<T>(int count) where T : unmanaged
+    {
+        return (T*)MemAlloc(count * sizeof(T));
+    }
+
     /// <summary>Load file data as byte array (read)</summary>
     public static byte* LoadFileData(string fileName, ref uint bytesRead)
     {