Add GL debug function

Signed-off-by: Leo Ma <begeekmyfriend@gmail.com>

app/src/main/java/com/seu/magicfilter/utils/OpenGLUtils.java

@@ -227,4 +227,15 @@ public class OpenGLUtils {
         }
         return body.toString();
     }
+
+    /**
+     * Checks to see if a GLES error has been raised.
+     */
+    public static void checkGlError(String op) {
+        int error = GLES20.glGetError();
+        if (error != GLES20.GL_NO_ERROR) {
+            String msg = op + ": glError 0x" + Integer.toHexString(error);
+            Log.e("OpenGlUtils", msg);
+        }
+    }
 }

app/src/main/res/raw/fragment_default.glsl

@@ -5,6 +5,5 @@ varying mediump vec2 textureCoordinate;
 uniform sampler2D inputImageTexture;
 
 void main() {
-    vec3 centralColor = texture2D(inputImageTexture, textureCoordinate).rgb;
-    gl_FragColor = vec4(centralColor.rgb,1.0);
-}
+    gl_FragColor = texture2D(inputImageTexture, textureCoordinate);
+}