🔢 Allow instanced vertex data

beardgame · Aug 5, 2024 · ad26246 · ad26246
1 parent a5979ae
commit ad26246
Show file tree

Hide file tree

Showing 3 changed files with 25 additions and 14 deletions.
diff --git a/Bearded.Graphics/Core/Vertices/VertexAttribute.cs b/Bearded.Graphics/Core/Vertices/VertexAttribute.cs
@@ -10,7 +10,8 @@ public readonly struct VertexAttribute(
     VertexAttribPointerType type,
     int stride,
     int offset,
-    VertexAttributeFormat format)
+    VertexAttributeFormat format,
+    int divisor)
 {
     public void SetAttribute(ShaderProgram program)
     {
@@ -37,6 +38,8 @@ public void SetAttribute(ShaderProgram program)
             default:
                 throw new ArgumentOutOfRangeException();
         }
+
+        GL.VertexAttribDivisor(index, divisor);
     }
 
     public override string ToString() =>

diff --git a/Bearded.Graphics/Core/Vertices/VertexAttributeTemplate.cs b/Bearded.Graphics/Core/Vertices/VertexAttributeTemplate.cs
@@ -7,8 +7,9 @@ public readonly struct VertexAttributeTemplate(
     int size,
     int bytes,
     VertexAttribPointerType type,
-    VertexAttributeFormat format)
+    VertexAttributeFormat format,
+    int divisor)
 {
     public int Bytes => bytes;
-    public VertexAttribute ToAttribute(int offset, int stride) => new(name, size, type, stride, offset, format);
+    public VertexAttribute ToAttribute(int offset, int stride) => new(name, size, type, stride, offset, format, divisor);
 }
diff --git a/Bearded.Graphics/Core/Vertices/VertexData.cs b/Bearded.Graphics/Core/Vertices/VertexData.cs
@@ -30,15 +30,19 @@ public static void SetAttributes<TCollection>(TCollection attributes, ShaderProg
     }
 
     public static ImmutableArray<VertexAttribute> MakeAttributeArray(IEnumerable<VertexAttributeTemplate> attributes)
-        => MakeAttributeArray(attributes.ToList());
+        => MakeAttributeArray(attributes.ToArray());
 
     public static ImmutableArray<VertexAttribute> MakeAttributeArray(params VertexAttributeTemplate[] attributes)
-        => MakeAttributeArray((ICollection<VertexAttributeTemplate>)attributes);
+        => MakeAttributeArray((ReadOnlySpan<VertexAttributeTemplate>)attributes);
 
-    public static ImmutableArray<VertexAttribute> MakeAttributeArray(ICollection<VertexAttributeTemplate> attributes)
+    public static ImmutableArray<VertexAttribute> MakeAttributeArray(ReadOnlySpan<VertexAttributeTemplate> attributes)
     {
-        var stride = attributes.Sum(a => a.Bytes);
-        var array = ImmutableArray.CreateBuilder<VertexAttribute>(attributes.Count);
+        var stride = 0;
+        foreach (var template in attributes)
+        {
+            stride += template.Bytes;
+        }
+        var array = ImmutableArray.CreateBuilder<VertexAttribute>(attributes.Length);
         var offset = 0;
         foreach (var template in attributes)
         {
@@ -49,28 +53,31 @@ public static ImmutableArray<VertexAttribute> MakeAttributeArray(ICollection<Ver
         return array.MoveToImmutable();
     }
 
-    public static VertexAttributeTemplate MakeAttributeTemplate<T>(string name, Format? format = null)
-        => MakeAttributeTemplate(name, typeof(T), format);
+    public static VertexAttributeTemplate MakeAttributeTemplate<T>(
+        string name, Format? format = null, bool instanced = false)
+        => MakeAttributeTemplate(name, typeof(T), format, instanced);
 
-    public static VertexAttributeTemplate MakeAttributeTemplate(string name, Type type, Format? format = null)
+    public static VertexAttributeTemplate MakeAttributeTemplate(
+        string name, Type type, Format? format = null, bool instanced = false)
     {
         if (!defaultsForType.TryGetValue(type, out var info))
             throw new ArgumentException($"Unknown type: {type.Name}");
 
         var bytes = size(info.Type);
 
-        return MakeAttributeTemplate(name, info.Type, info.Count, info.Count * bytes, format ?? info.DefaultFormat);
+        return MakeAttributeTemplate(
+            name, info.Type, info.Count, info.Count * bytes, format ?? info.DefaultFormat, instanced);
     }
 
     public static VertexAttributeTemplate MakeAttributeTemplate(
-        string name, PointerType type, int numberOfType, int sizeInBytes, Format format)
+        string name, PointerType type, int numberOfType, int sizeInBytes, Format format, bool instanced)
     {
         if (format == Format.Integer && !isValidIntegerType(type))
             throw new ArgumentException("Invalid type for integer vertex attribute. Must be an integer.");
         if (format == Format.Double && type != PointerType.Double)
             throw new ArgumentException("Invalid type for 64-bit vertex attribute. Must be Double.");
 
-        return new VertexAttributeTemplate(name, numberOfType, sizeInBytes, type, format);
+        return new VertexAttributeTemplate(name, numberOfType, sizeInBytes, type, format, instanced ? 1 : 0);
     }
 
     private static bool isValidIntegerType(PointerType type)