diff --git a/assets/shaders/fragment.glsl b/assets/shaders/fragment.glsl
index 35ee8d4..2453774 100644
--- a/assets/shaders/fragment.glsl
+++ b/assets/shaders/fragment.glsl
@@ -1,7 +1,8 @@
 
+uniform bool side;
 varying vec3 color_i;
 
 void main()
 {
-    gl_FragColor = vec4(color_i, 1);
+    gl_FragColor = vec4(side ? color_i.bgr : color_i, 1);
 }
diff --git a/src/com/homelinux/holtrop/opengltest/MyRenderer.java b/src/com/homelinux/holtrop/opengltest/MyRenderer.java
index e42047c..679505c 100644
--- a/src/com/homelinux/holtrop/opengltest/MyRenderer.java
+++ b/src/com/homelinux/holtrop/opengltest/MyRenderer.java
@@ -233,6 +233,9 @@ public class MyRenderer implements GLSurfaceView.Renderer
                 GLES20.glUniformMatrix4fv(
                         GLES20.glGetUniformLocation(m_program, "modelview"),
                         1, false, m_modelview, 0);
+                GLES20.glUniform1i(
+                        GLES20.glGetUniformLocation(m_program, "side"),
+                        t.side ? 1 : 0);
 
                 GLES20.glDrawArrays(GLES20.GL_TRIANGLE_FAN, 0, 4);
                 checkGLError("glDrawArrays");