/// <summary>
/// Set uniform state variable (floating-point variable).
/// </summary>
/// <param name="ctx">
/// A <see cref="GraphicsContext"/> used for operations.
/// </param>
/// <param name="uniformName">
/// A <see cref="String"/> that specify the variable name in the shader source.
/// </param>
/// <param name="v">
/// A <see cref="Single"/> holding the uniform variabile data.
/// </param>
public void SetUniformBlock(GraphicsContext ctx, string uniformBlockName, UniformBuffer uniformBuffer)
{
if (ctx == null)
{
throw new ArgumentNullException("ctx");
}
if (uniformBuffer == null)
{
throw new ArgumentNullException("uniformBuffer");
}
// Select a binding point, if still invalid
ctx.Bind(uniformBuffer);
UniformBlockBinding uniformBlockBinding = GetUniformBlock(uniformBlockName);
if (uniformBlockBinding == null)
{
throw new ArgumentException("no uniform block with such name", "uniformBlockName");
}
#if ENABLE_UNIFORM_BLOCK_CACHING
if (IsUniformBlockChanged(uniformBlockBinding.Index, uniformBuffer) == false)
{
return;
}
#endif
// Link the uniform buffer
Gl.UniformBlockBinding(ObjectName, uniformBlockBinding.Index, uniformBuffer.BindingIndex);
#if ENABLE_UNIFORM_BLOCK_CACHING
CacheUniformBlock(uniformBlockBinding.Index, uniformBuffer);
#endif
}
/// <summary>
/// Determine whether if an uniform value is different from the one currently cached.
/// </summary>
/// <param name="uniformName">
/// A <see cref="String"/> that specifies the uniform variable name.
/// </param>
/// <param name="uniformValue">
/// A <see cref="Object"/> that specifies the uniform variable value updated.
/// </param>
/// <returns>
/// It returns a boolean value indicating whether <paramref name="uniformValue"/> is actually
/// different from the current uniform value.
/// </returns>
private bool IsUniformBlockChanged(uint index, UniformBuffer uniformBuffer)
{
uint cachedBindingIndex;
if (_UniformBlocks.TryGetValue(index, out cachedBindingIndex) == false)
{
return(true);
}
return(cachedBindingIndex != uniformBuffer.BindingIndex);
}
/// <summary>
/// Create an <see cref="UniformBuffer"/> useful for backing with a buffer object the specified uniform block.
/// </summary>
/// <param name="uniformBlockName"></param>
/// <param name="usageMask"></param>
/// <returns></returns>
public UniformBuffer CreateUniformBlock(string uniformBlockName, MapBufferUsageMask usageMask)
{
UniformBlockBinding uniformBlockBinding = GetUniformBlock(uniformBlockName);
if (uniformBlockBinding == null)
{
throw new ArgumentException("no uniform block with such name", "uniformBlockName");
}
UniformBuffer uniformBuffer = new UniformBuffer(usageMask);
// Allocate client storage
uniformBuffer.Create(uniformBlockBinding.DataSize);
// Map uniform names with
MapUniformBlock(uniformBlockName, uniformBuffer);
return(uniformBuffer);
}
private void MapUniformBlock(string uniformBlockName, UniformBuffer uniformBuffer)
{
UniformBlockBinding uniformBlockBinding = GetUniformBlock(uniformBlockName);
if (uniformBlockBinding == null)
{
throw new ArgumentException("no uniform block with such name", "uniformBlockName");
}
for (int i = 0; i < uniformBlockBinding.UniformIndices.Length; i++)
{
uint uniformIndex = uniformBlockBinding.UniformIndices[i];
UniformBinding uniformBinding;
if (_UniformIndexMap.TryGetValue(uniformIndex, out uniformBinding) == false)
{
throw new InvalidOperationException("uniform buffer index mismatch with uniforms");
}
UniformBuffer.UniformSegment uniformSegment = new UniformBuffer.UniformSegment();
uniformSegment.UniformIndex = uniformIndex;
uniformSegment.Type = uniformBinding.UniformType;
uniformSegment.Offset = uniformBinding.BlockOffset;
uniformSegment.ArrayStride = uniformBinding.BlockArrayStride;
uniformSegment.MatrixStride = uniformBinding.BlockMatrixStride;
uniformSegment.RowMajor = uniformBinding.BlockMatrixRowMajor;
uniformBuffer._UniformSegments[uniformBinding.Name] = uniformSegment;
}
foreach (KeyValuePair <string, UniformBinding> pair in _UniformMap)
{
if (pair.Value != null)
{
continue;
}
uniformBuffer._UniformSegments[pair.Key] = null;
}
}
/// <summary>
/// Cache the current uniform value. Used to minimize Uniform* calls at the cost of comparing the cached
/// object with the call arguments.
/// </summary>
/// <param name="uniformName">
/// A <see cref="String"/> that specifies the uniform variable name.
/// </param>
/// <param name="uniformValue">
/// A <see cref="Object"/> that specifies the uniform variable value.
/// </param>
private void CacheUniformBlock(uint index, UniformBuffer uniformBuffer)
{
Debug.Assert(uniformBuffer != null);
_UniformBlocks[index] = uniformBuffer.BindingIndex;
}
