static void BindInstanceAttributes(MeshInstanced instance, int stride, InstanceAttributeMappingCollection attributes)
{
var vertexStride = 0;
var mesh = instance.InstanceMesh;
var vertexAttributes = new List<VertexAttributeMapping>();
GL.BindVertexArray(mesh.VertexArray);
for (int i = 0; ; i++)
{
int enabled;
GL.GetVertexAttrib(i, VertexAttribParameter.ArrayEnabled, out enabled);
if (enabled == 0) break;
int size, type, normalized, vstride;
var attribute = new VertexAttributeMapping();
GL.GetVertexAttrib(i, VertexAttribParameter.ArraySize, out size);
GL.GetVertexAttrib(i, VertexAttribParameter.ArrayType, out type);
GL.GetVertexAttrib(i, VertexAttribParameter.ArrayNormalized, out normalized);
GL.GetVertexAttrib(i, VertexAttribParameter.ArrayStride, out vstride);
if (vertexStride == 0) vertexStride = vstride;
else if (vstride != vertexStride)
{
throw new InvalidOperationException("Meshes with interleaved vertex buffers are not supported.");
}
attribute.Size = size;
attribute.Type = (VertexAttribPointerType)type;
attribute.Normalized = normalized != 0 ? true : false;
vertexAttributes.Add(attribute);
}
var offset = 0;
GL.BindVertexArray(instance.VertexArray);
GL.BindBuffer(BufferTarget.ArrayBuffer, mesh.VertexBuffer);
for (int i = 0; i < vertexAttributes.Count; i++)
{
var attribute = vertexAttributes[i];
GL.EnableVertexAttribArray(i);
GL.VertexAttribPointer(
i, attribute.Size,
attribute.Type,
attribute.Normalized,
vertexStride, offset);
offset += attribute.Size * VertexHelper.GetVertexAttributeSize(attribute.Type);
}
offset = 0;
GL.BindBuffer(BufferTarget.ArrayBuffer, instance.VertexBuffer);
for (int i = 0; i < attributes.Count; i++)
{
var attribute = attributes[i];
var index = i + vertexAttributes.Count;
GL.EnableVertexAttribArray(index);
GL.VertexAttribPointer(
index, attribute.Size,
attribute.Type,
attribute.Normalized,
stride, offset);
GL.VertexAttribDivisor(index, attribute.Divisor);
offset += attribute.Size * VertexHelper.GetVertexAttributeSize(attribute.Type);
}
GL.BindBuffer(BufferTarget.ArrayBuffer, 0);
GL.BindVertexArray(0);
}
