/// <summary>
/// Actually create this BufferObject resources.
/// </summary>
/// <param name="ctx">
/// A <see cref="GraphicsContext"/> used for allocating resources.
/// </param>
/// <exception cref="ArgumentNullException">
/// Exception thrown if <paramref name="ctx"/> is null.
/// </exception>
/// <exception cref="ArgumentException">
/// Exception thrown if <paramref name="ctx"/> is not current on the calling thread.
/// </exception>
/// <exception cref="InvalidOperationException">
/// Exception thrown if this BufferObject has not client memory allocated and the hint is different from
/// <see cref="BufferObjectHint.StaticCpuDraw"/> or <see cref="BufferObjectHint.DynamicCpuDraw"/>.
/// </exception>
/// <exception cref="InvalidOperationException">
/// Exception thrown if this BufferObject is currently mapped.
/// </exception>
protected override void CreateObject(GraphicsContext ctx)
{
// Base implementation
base.CreateObject(ctx);
// Compute necessary information to support primitive restart even if the platform does not implement it
if (!PrimitiveRestart.IsPrimitiveRestartSupported(ctx) && RestartIndexEnabled)
{
PrimitiveRestartOffsets = GetRestartIndices(out PrimitiveRestartCounts);
}
}
/// <summary>
/// Draw the elements instances
/// </summary>
/// <param name="ctx">
/// The <see cref="GraphicsContext"/> used for drawing.
/// </param>
/// <param name="instances">
/// A <see cref="UInt32"/> that specify the number of instances to draw.
/// </param>
public override void DrawInstanced(GraphicsContext ctx, uint instances)
{
CheckCurrentContext(ctx);
ArrayBufferObjectBase.IArraySection arraySection = ArrayIndices.GetArraySection(0);
Debug.Assert(arraySection != null);
// Element array must be (re)bound
ctx.Bind(ArrayIndices, true);
// Enable restart primitive?
if (ArrayIndices.RestartIndexEnabled)
{
if (PrimitiveRestart.IsPrimitiveRestartSupported(ctx))
{
// Enable primitive restart
PrimitiveRestart.EnablePrimitiveRestart(ctx, ArrayIndices.ElementsType);
// Draw elements as usual
DrawElementsInstanced(ctx, arraySection.Pointer, instances);
// Disable primitive restart
PrimitiveRestart.DisablePrimitiveRestart(ctx);
}
else
{
throw new NotSupportedException();
}
}
else
{
uint count = (ElementCount == 0) ? ArrayIndices.ItemCount : ElementCount;
Debug.Assert(count - ElementOffset <= ArrayIndices.ItemCount, "element indices array out of bounds");
// Draw vertex arrays by indices
DrawElementsInstanced(ctx, arraySection.Pointer, instances);
}
}
/// <summary>
/// Draw the elements.
/// </summary>
/// <param name="ctx">
/// The <see cref="GraphicsContext"/> used for drawing.
/// </param>
public override void Draw(GraphicsContext ctx)
{
CheckCurrentContext(ctx);
ArrayBufferObjectBase.IArraySection arraySection = ArrayIndices.GetArraySection(0);
Debug.Assert(arraySection != null);
// Element array must be (re)bound
ctx.Bind(ArrayIndices, true);
// Enable restart primitive?
if (ArrayIndices.RestartIndexEnabled)
{
if (PrimitiveRestart.IsPrimitiveRestartSupported(ctx))
{
// Draw elements with primitive restart
PrimitiveRestart.EnablePrimitiveRestart(ctx, ArrayIndices.ElementsType);
DrawElements(ctx, arraySection.Pointer);
PrimitiveRestart.DisablePrimitiveRestart(ctx);
}
else
{
// Note: uses MultiDrawElements to emulate the primitive restart feature; PrimitiveRestartOffsets and
// PrimitiveRestartCounts are computed at element buffer creation time
Gl.MultiDrawElements(ElementsMode, ArrayIndices.PrimitiveRestartOffsets, ArrayIndices.ElementsType, ArrayIndices.PrimitiveRestartCounts, ArrayIndices.PrimitiveRestartOffsets.Length);
}
}
else
{
uint count = (ElementCount == 0) ? ArrayIndices.ItemCount : ElementCount;
Debug.Assert(count - ElementOffset <= ArrayIndices.ItemCount, "element indices array out of bounds");
// Draw vertex arrays by indices
DrawElements(ctx, arraySection.Pointer);
}
}
