Require the first keyframe of an animation to be at zero offset

Having empty space at the start of an animation produces unexpected
results.

diff --git a/source/animation.cpp b/source/animation.cpp
index b58a4ea77e0e0c3193c2eec31074aa91912b72c7..02a2d371c71c1d32baff99aa3a120429d8c90d91 100644 (file)
--- a/source/animation.cpp
+++ b/source/animation.cpp
@@ -61,6 +61,8 @@ void Animation::add_keyframe(const Time::TimeDelta &t, const KeyFrame &kf, float
 
 void Animation::add_keyframe(const Time::TimeDelta &t, const RefPtr<const KeyFrame> &kf, float ss, float es)
 {
+       if(keyframes.empty() && t!=Time::zero)
+               throw invalid_argument("Animation::add_keyframe");
        if(!keyframes.empty() && t<keyframes.back().time)
                throw invalid_argument("Animation::add_keyframe");