commit 9d7f6e67815be260862e2af6ef59fbdcfc186d54
Author: Dalai Felinto <dfelinto@gmail.com>
Date:   Mon Jun 12 16:39:47 2017 +0200

    Fix T50973: Directional blur node doesn't clamp value if using driver

diff --git a/source/blender/compositor/operations/COM_DirectionalBlurOperation.cpp b/source/blender/compositor/operations/COM_DirectionalBlurOperation.cpp
index 14881ebb265..beac8e5fbec 100644
--- a/source/blender/compositor/operations/COM_DirectionalBlurOperation.cpp
+++ b/source/blender/compositor/operations/COM_DirectionalBlurOperation.cpp
@@ -46,10 +46,13 @@ void DirectionalBlurOperation::initExecution()
 	const float spin = this->m_data->spin;
 	const float iterations = this->m_data->iter;
 	const float distance = this->m_data->distance;
-	const float center_x = this->m_data->center_x;
-	const float center_y = this->m_data->center_y;
 	const float width = getWidth();
 	const float height = getHeight();
+	float center_x = this->m_data->center_x;
+	float center_y = this->m_data->center_y;
+
+	CLAMP(center_x, 0.0f, 1.0f);
+	CLAMP(center_y, 0.0f, 1.0f);
 
 	const float a = angle;
 	const float itsc = 1.0f / powf(2.0f, (float)iterations);