diff --git a/samplecode/SampleTestGL.cpp b/samplecode/SampleTestGL.cpp
index c5938ba..a0dfea3 100644
--- a/samplecode/SampleTestGL.cpp
+++ b/samplecode/SampleTestGL.cpp
@@ -50,7 +50,7 @@
     "    float u = uv.x;"
     "    float v = uv.y;"
     "    if (u*u > v) {"
-"    gl_FragColor = vec4(1.0, 0, 0, 1.0);"
+"    gl_FragColor = vec4(0.0, 0, 0, 0.0);"
     "    } else {"
     "    gl_FragColor = vec4(0, 1.0, 0, 1.0);"
     "}"