Android - OpenGL ES 2.0 : Emulator (Works) - Device (Doesn't)

Question

Good day!

I am doing some simple tests with OpenGL ES 2.0 for Android. I am using a model loader that works well in the Emulator. However, when I try to use it on a ASUS ZenFone 2E (Android 5.0.1) (Prepaid Phone) it simply shows the clear color of the background with no rotating model. I am hoping that someone who is well experienced in both OpenGL ES 2.0 and Android will assist me. Sorry for the verbosity, I really have no idea why it isn't working on the phone. Here is the source (I'm an extreme novice):

GameView.java:

package wise.child.dials;

import android.content.Context;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.Matrix;
import android.os.SystemClock;

import java.io.IOException;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import model.Model;
import render.Program;
import render.Shader;
import util.OBJLoader;

public class GameView extends GLSurfaceView implements GLSurfaceView.Renderer {

    // App Context
    private Context mContext;

    // Handles
    private int mPositionHandle;
    private int mColorHandle;
    private int mMVPMatrixHandle;

    // Program & Shaders
    private Program testProgram;
    private Shader testVertexShader;
    private Shader testFragmentShader;

    // Model
    private Model model;
    private FloatBuffer vertexFloatBuffer;
    private int vertexCount;

    // Matrices
    private final float[] mMVPMatrix = new float[16];
    private final float[] mProjectionMatrix = new float[16];
    private final float[] mViewMatrix = new float[16];
    private float[] mRotationMatrix = new float[16];

    // Constructor
    public GameView(Context context) {
        super(context);

        // App Context
        mContext = context;

        // OpenGL ES 2.0 Context
        setEGLContextClientVersion(2);

        // Renderer
        setRenderer(this);
    }

    /*-------------------*/
    /* Rendering Methods */
    /*-------------------*/

    // One Time Initialization
    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        GLES20.glClearColor(0.95f, 0.95f, 0.95f, 1f);

        // Initialize Shaders
        testVertexShader = new Shader(GLES20.GL_VERTEX_SHADER, mContext, R.raw.test_vertex_shader);
        testFragmentShader = new Shader(GLES20.GL_FRAGMENT_SHADER, mContext, R.raw.test_fragment_shader);

        // Create Program
        testProgram = new Program(testVertexShader, testFragmentShader);
        testProgram.use();

        // Get Handles - Uniforms & Attributes
        mPositionHandle = testProgram.getAttribute("vPosition");
        mColorHandle = testProgram.getUniform("vColor");
        mMVPMatrixHandle = testProgram.getUniform("uMVPMatrix");

        // Model
        try {
            model = OBJLoader.loadOBJ(mContext, R.raw.spider);
            vertexFloatBuffer = model.getVerticesFromIndices();
            vertexCount = model.getVertexCount();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    // Drawing Call
    @Override
    public void onDrawFrame(GL10 gl) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

        // Time and Rotation Animation
        float[] scratch = new float[16];
        long time = SystemClock.uptimeMillis() % 4000L;
        float angle = 0.090f * ((int) time);
        Matrix.setRotateM(mRotationMatrix, 0, angle, angle, angle, angle);

        // Set and Bind Data
        GLES20.glEnableVertexAttribArray(mPositionHandle);
        GLES20.glVertexAttribPointer(mPositionHandle, 3, GLES20.GL_FLOAT, false, 12, vertexFloatBuffer);

        // Set Color
        float[] color = {.75f, 0f, 0f, 1f};
        GLES20.glUniform4fv(mColorHandle, 1, color, 0);

        // Camera Position - View Matrix
        Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -15, 0f, 0f, 0f, 0f, 1.0f, 0.0f);

        // Projection x View
        Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);

        // Rotation x MVP
        Matrix.multiplyMM(scratch, 0, mMVPMatrix, 0, mRotationMatrix, 0);

        // Final Matrix
        GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, scratch, 0);

        // Draw
        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);

        // Disable
        GLES20.glDisableVertexAttribArray(mPositionHandle);

    }

    // GLSurface Changed
    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        // GL Viewport & Aspect Ratio
        GLES20.glViewport(0, 0, width, height);
        float aspectRatio = (float) width / height;

        // Calculate Projection
        Matrix.frustumM(mProjectionMatrix, 0, -aspectRatio, aspectRatio, -1, 1, 3, 50);
    }

}

Shader.java

package render;

import android.content.Context;
import android.opengl.GLES20;
import android.util.Log;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Shader {

    // Shader Source Code
    public String shaderSource;

    // Shader Handle
    public int shaderHandle;

    public int programHandle;

    public Shader(int type, Context context, int resID) {

        try {
            shaderSource = loadShader(context, resID);
            Log.d("Shader Load", "Success!");
            System.out.println(shaderSource);
        } catch (IOException e) {
            Log.d("Shader Load", "Failed.");
            e.printStackTrace();
        }

        shaderHandle = GLES20.glCreateShader(type);
        GLES20.glShaderSource(shaderHandle, shaderSource);
        GLES20.glCompileShader(shaderHandle);

    }

    // Get From Raw Folder
    private String loadShader(Context context, int resID) throws IOException {

        BufferedReader reader = new BufferedReader(
                new InputStreamReader(context.getResources().openRawResource(resID))
        );

        String line, shader;
        StringBuilder builder = new StringBuilder();

        while ((line = reader.readLine()) != null) {
            builder.append(line).append('\n');
        }

        reader.close();

        shader = builder.toString();

        return shader;
    }

    // Associated Program
    public void setProgram(int handle) {
        programHandle = handle;
    }


}

Program.java

package render;

import android.opengl.GLES20;

import java.util.ArrayList;
import java.util.List;

public class Program {

    public int handle;

    private Shader vertexShader;
    private Shader fragmentShader;

    private List<String> attributes = new ArrayList<String>();
    private List<String> uniforms = new ArrayList<String>();

    public Program(Shader vertexShader, Shader fragmentShader) {
        this.vertexShader = vertexShader;
        this.fragmentShader = fragmentShader;

        this.vertexShader.setProgram(handle);
        this.fragmentShader.setProgram(handle);

        handle = GLES20.glCreateProgram();
        GLES20.glAttachShader(handle, vertexShader.shaderHandle);
        GLES20.glAttachShader(handle, fragmentShader.shaderHandle);
        GLES20.glLinkProgram(handle);


    }

    public void use() {
        GLES20.glUseProgram(handle);
    }

    public int getAttribute(String name) {
        return GLES20.glGetAttribLocation(handle, name);
    }

    public void setAttribute(String name) {

    }

    public int getUniform(String name) {
        return GLES20.glGetUniformLocation(handle, name);
    }
}

Model.java

package model;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.util.ArrayList;
import java.util.List;

public class Model {

    private static final int NUM_OF_COORDS = 3;

    public List<Vertex> vertices = new ArrayList<Vertex>();
    public List<Vertex> normals = new ArrayList<Vertex>();
    public List<Face> faces = new ArrayList<Face>();

    public Model() {}

    public int getVertexCount() {
        return faces.size() * NUM_OF_COORDS;
    }

    public FloatBuffer getVerticesFromIndices() {

        int numOfVertices = 3;
        int bytesPerFloat = 4;

        ByteBuffer bb = ByteBuffer.allocateDirect(faces.size() * numOfVertices * NUM_OF_COORDS * bytesPerFloat);
        bb.order(ByteOrder.nativeOrder());
        FloatBuffer vertexFloatBuffer = bb.asFloatBuffer();

        // Use indices to find proper vertex
        for (Face face : faces) {

            // VERTEX 1
            vertexFloatBuffer.put(vertices.get((int) (face.vertex.x - 1)).x);
            vertexFloatBuffer.put(vertices.get((int) (face.vertex.x - 1)).y);
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.x - 1)).z);

            // VERTEX 2
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.y - 1)).x);
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.y - 1)).y);
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.y - 1)).z);

            // VERTEX 3
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.z - 1)).x);
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.z - 1)).y);
            vertexFloatBuffer.put(vertices.get((int)(face.vertex.z - 1)).z);
        }

        vertexFloatBuffer.position(0);

        return vertexFloatBuffer;
    }

    public FloatBuffer getNormalsFromIndices() {

        int numOfVertices = 3;
        int bytesPerFloat = 4;

        ByteBuffer bb = ByteBuffer.allocateDirect(faces.size() * numOfVertices * NUM_OF_COORDS * bytesPerFloat);
        bb.order(ByteOrder.nativeOrder());
        FloatBuffer normalFloatBuffer = bb.asFloatBuffer();

        // Use indices to find proper normal
        for (Face face : faces) {

            // VERTEX 1
            normalFloatBuffer.put(normals.get((int) (face.normal.x - 1)).x);
            normalFloatBuffer.put(normals.get((int) (face.normal.x - 1)).y);
            normalFloatBuffer.put(normals.get((int)(face.normal.x - 1)).z);

            // VERTEX 2
            normalFloatBuffer.put(normals.get((int)(face.normal.y - 1)).x);
            normalFloatBuffer.put(normals.get((int)(face.normal.y - 1)).y);
            normalFloatBuffer.put(normals.get((int)(face.normal.y - 1)).z);

            // VERTEX 3
            normalFloatBuffer.put(normals.get((int)(face.normal.z - 1)).x);
            normalFloatBuffer.put(normals.get((int)(face.normal.z - 1)).y);
            normalFloatBuffer.put(normals.get((int)(face.normal.z - 1)).z);
        }

        normalFloatBuffer.position(0);

        return normalFloatBuffer;
    }


}

OBJLoader.java

package util;

import android.content.Context;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import model.Face;
import model.Model;
import model.Vertex;

public class OBJLoader {

    /* loads .obj data from file in res/raw folder */
    public static Model loadOBJ(Context context, int resID) throws IOException {

        Model model = new Model();

        BufferedReader reader = new BufferedReader(
                new InputStreamReader(context.getResources().openRawResource(resID))
        );

        String line;

        while ((line = reader.readLine()) != null) {
            if (line.startsWith("v ")) {
                // Vertex
                float x = Float.valueOf(line.split(" ")[1]);
                float y = Float.valueOf(line.split(" ")[2]);
                float z = Float.valueOf(line.split(" ")[3]);
                model.vertices.add(new Vertex(x, y, z));

            } else if (line.startsWith("vn ")) {
                // Normal
                float x = Float.valueOf(line.split(" ")[1]);
                float y = Float.valueOf(line.split(" ")[2]);
                float z = Float.valueOf(line.split(" ")[3]);
                model.normals.add(new Vertex(x, y, z));

            } else if (line.startsWith("f ")) {
                // Face
                Vertex vertexIndices = new Vertex(
                        Float.valueOf(line.split(" ")[1].split("/")[0]),
                        Float.valueOf(line.split(" ")[2].split("/")[0]),
                        Float.valueOf(line.split(" ")[3].split("/")[0])
                );

                Vertex normalIndices = new Vertex(
                        Float.valueOf(line.split(" ")[1].split("/")[2]),
                        Float.valueOf(line.split(" ")[2].split("/")[2]),
                        Float.valueOf(line.split(" ")[3].split("/")[2])
                );

                model.faces.add(new Face(vertexIndices, normalIndices));
            }
        }

        reader.close();

        return model;
    }
}

MainActivity.java

package wise.child.dials;

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Fullscreen & No Title Bar
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        // Set OpenGL ES Drawing Surface (Game View)
        setContentView(new GameView(this));
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="wise.child.dials">

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <supports-gl-texture android:name="GL_OES_compressed_ETC1_RGB8_texture" />
    <supports-gl-texture android:name="GL_OES_compressed_paletted_texture" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MenuActivity"
            android:screenOrientation="landscape"
            android:theme="@android:style/Theme.Holo.NoActionBar.Fullscreen">
        </activity>

        <activity
            android:name=".MainActivity"
            android:screenOrientation="landscape"
            android:theme="@android:style/Theme.Holo.NoActionBar.Fullscreen">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".SplashScreen" />
    </application>

</manifest>

Vertex Shader

attribute vec4 vPosition;

uniform mat4 uMVPMatrix;

void main() {
    gl_Position = uMVPMatrix * vPosition;
}

Fragment Shader

uniform vec4 vColor;

void main() {
    gl_FragColor = vColor;
}

Answer 1

The Solution to this Particular Issue:

So, I added this line to my fragment shader:

precision mediump float;

to give us:

Fragment Shader

precision mediump float;

uniform vec4 vColor;

void main() {
    gl_FragColor = vColor;
}

Why this worked, I'm embarrassed to say that I do not know. If anybody is willing to elaborate further, please do I am curious. I'm still learning OpenGL ES 2.0. In my reading of OpenGL ES 2.0 Programming Guide (Good Book), I came across that line. And they noted, "In OpenGL ES 2.0, nothing can be drawn unless a valid vertex and fragment shader have been loaded." The Android tutorial also included this line, so I know it's critical.