Avoid checking automatic program inputs (gl_VertexID).

1 files changed, 5 insertions, 1 deletions

diff --git a/src/LambdaCube/GL/Backend.hs b/src/LambdaCube/GL/Backend.hs
index f3bfe47..50d0d3f 100644
--- a/src/LambdaCube/GL/Backend.hs
+++ b/src/LambdaCube/GL/Backend.hs
@@ -257,7 +257,11 @@ compileProgram p = do
 
     -- check program input
     (uniforms,uniformsType) <- queryUniforms po
-    (attributes,attributesType) <- queryStreams po
+    (attributes,attributesType) <- do
+        (as,ts) <- queryStreams po
+        let builtins = Map.singleton "gl_VertexID" () -- Avoid checking automatic inputs.
+        return (as Map.\\ builtins, ts Map.\\ builtins)
+
     --print uniforms
     --print attributes
     let lcUniforms = (programUniforms p) `Map.union` (programInTextures p)