/// <summary>
/// Generates an independent buffer.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="array"></param>
/// <param name="target"></param>
/// <param name="usage"></param>
/// <returns></returns>
private static Buffer GenIndependentBuffer <T>(this T[] array, IndependentBufferTarget target, BufferUsage usage) where T : struct
{
GCHandle pinned = GCHandle.Alloc(array, GCHandleType.Pinned);
IntPtr header = Marshal.UnsafeAddrOfPinnedArrayElement(array, 0);
UnmanagedArrayBase unmanagedArray = UnmanagedArray <T> .FromHandle(header, array.Length);// It's not neecessary to call Dispose() for this unmanaged array.
Buffer buffer = GenIndependentBuffer(unmanagedArray, target, usage);
pinned.Free();
return(buffer);
}
/// <summary>
/// 获取顶点属性Buffer。描述顶点的位置或颜色或UV等各种属性。
/// <para>每个<see cref="VertexBuffer"/>仅描述其中一个属性。</para>
/// <para>Vertex Buffer Object that describes vertex' property(position, color, uv coordinate, etc.).</para>
/// <para>Each <see cref="VertexBuffer"/> describes only 1 property.</para>
/// </summary>
/// <param name="array"></param>
/// <param name="config">This <paramref name="config"/> decides parameters' values in glVertexAttribPointer(attributeLocation, size, type, false, 0, IntPtr.Zero);</param>
/// <param name="varNameInVertexShader">此顶点属性VBO对应于vertex shader中的哪个in变量？<para>Mapping variable's name in vertex shader.</para></param>
/// <param name="usage"></param>
/// <param name="instancedDivisor">0: not instanced. 1: instanced divisor is 1.</param>
/// <param name="patchVertexes">How many vertexes makes a patch? No patch if <paramref name="patchVertexes"/> is 0.</param>
/// <returns></returns>
public static VertexBuffer GenVertexBuffer <T>(this T[] array, VBOConfig config, string varNameInVertexShader, BufferUsage usage, uint instancedDivisor = 0, int patchVertexes = 0) where T : struct
{
GCHandle pinned = GCHandle.Alloc(array, GCHandleType.Pinned);
IntPtr header = Marshal.UnsafeAddrOfPinnedArrayElement(array, 0);
UnmanagedArrayBase unmanagedArray = UnmanagedArray <T> .FromHandle(header, array.Length);// It's not neecessary to call Dispose() for this unmanaged array.
VertexBuffer buffer = GenVertexBuffer(unmanagedArray, config, varNameInVertexShader, usage, instancedDivisor, patchVertexes);
pinned.Free();
return(buffer);
}
/// <summary>
/// Fill all or part of buffer object's data store with a fixed value.
/// </summary>
/// <param name="offset">The offset, in basic machine units into the buffer object's data store at which to start filling.</param>
/// <param name="size">The size, in basic machine units of the range of the data store to fill.</param>
/// <param name="data">Specifies a pointer to a single pixel of data to upload. This parameter may not be null.</param>
/// <param name="autoBind">Automatically call glBindBuffer() inside this method.</param>
/// <returns></returns>
public bool ClearBufferSubData(int offset, uint size, vec3 data, bool autoBind = true)
{
var array = new vec3[] { data };
GCHandle pin = GCHandle.Alloc(array, GCHandleType.Pinned);
IntPtr header = Marshal.UnsafeAddrOfPinnedArrayElement(array, 0);
UnmanagedArrayBase unmanagedArray = UnmanagedArray <vec3> .FromHandle(header, 1);
bool result = ClearBufferSubData(OpenGL.GL_RGB32F, new IntPtr(offset), size, OpenGL.GL_RGB, OpenGL.GL_FLOAT, unmanagedArray, autoBind);
pin.Free();
return(result);
}
/// <summary>
/// 生成一个用于存储索引的VBO。索引指定了<see cref="VertexBuffer"/>里各个顶点的渲染顺序。
/// Generates a Vertex Buffer Object storing vertexes' indexes, which indicate the rendering order of each vertex.
/// </summary>
/// <param name="array"></param>
/// <param name="mode">用哪种方式渲染各个顶点？（OpenGL.GL_TRIANGLES etc.）</param>
/// <param name="usage"></param>
/// <param name="primCount">primCount in instanced rendering.</param>
/// <returns></returns>
private static OneIndexBuffer GenIndexBuffer <T>(this T[] array, DrawMode mode, BufferUsage usage, int primCount = 1) where T : struct
{
IndexBufferElementType elementType;
if (typeof(T) == typeof(uint))
{
elementType = IndexBufferElementType.UInt;
}
else if (typeof(T) == typeof(ushort))
{
elementType = IndexBufferElementType.UShort;
}
else if (typeof(T) == typeof(byte))
{
elementType = IndexBufferElementType.UByte;
}
else
{
throw new ArgumentException(string.Format("Only uint/ushort/byte are allowed!"));
}
if (glGenBuffers == null)
{
InitFunctions();
}
GCHandle pinned = GCHandle.Alloc(array, GCHandleType.Pinned);
IntPtr header = Marshal.UnsafeAddrOfPinnedArrayElement(array, 0);
UnmanagedArrayBase unmanagedArray = UnmanagedArray <T> .FromHandle(header, array.Length);// It's not neecessary to call Dispose() for this unmanaged array.
var buffers = new uint[1];
{
glGenBuffers(1, buffers);
const uint target = OpenGL.GL_ELEMENT_ARRAY_BUFFER;
glBindBuffer(target, buffers[0]);
glBufferData(target, unmanagedArray.ByteLength, unmanagedArray.Header, (uint)usage);
glBindBuffer(target, 0);
}
pinned.Free();
var buffer = new OneIndexBuffer(buffers[0], mode, elementType, unmanagedArray.Length, unmanagedArray.ByteLength, primCount);
return(buffer);
}