Working OpenGLES demo.

app/.gitignore

@@ -0,0 +1 @@
+/build

app/build.gradle

@@ -0,0 +1,30 @@
+apply plugin: 'com.android.application'
+
+android {
+    compileSdkVersion 25
+    buildToolsVersion "25.0.3"
+    defaultConfig {
+        applicationId "com.codigoparallevar.minicards"
+        minSdkVersion 15
+        targetSdkVersion 25
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    androidTestImplementation('com.android.support.test.espresso:espresso-core:2.2.2', {
+        exclude group: 'com.android.support', module: 'support-annotations'
+    })
+    implementation 'com.android.support:appcompat-v7:25.4.0'
+    testImplementation 'junit:junit:4.12'
+    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
+}

app/proguard-rules.pro

@@ -0,0 +1,25 @@
+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in /home/kenkeiras/android-sdk-linux/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

app/src/androidTest/java/com/codigoparallevar/minicards/ExampleInstrumentedTest.java

@@ -0,0 +1,26 @@
+package com.codigoparallevar.minicards;
+
+import android.content.Context;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() throws Exception {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getTargetContext();
+
+        assertEquals("com.codigoparallevar.minicards", appContext.getPackageName());
+    }
+}

app/src/main/AndroidManifest.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.codigoparallevar.minicards">
+
+    <!-- OpenGL ES 2.0 -->
+
+    <uses-feature android:glEsVersion="0x00020000" android:required="true" />
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+
+
+        <activity android:name=".TestActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

app/src/main/java/com/codigoparallevar/minicards/TestActivity.java

@@ -0,0 +1,22 @@
+package com.codigoparallevar.minicards;
+
+import android.opengl.GLSurfaceView;
+import android.support.v7.app.AppCompatActivity;
+import android.os.Bundle;
+
+import com.codigoparallevar.minicards.rendering.MyGLSurfaceView;
+
+public class TestActivity extends AppCompatActivity {
+
+    private GLSurfaceView mGLView;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        // Create a GLSurfaceView instance and set it
+        // as the ContentView for this Activity.
+        mGLView = new MyGLSurfaceView(this);
+        setContentView(mGLView);
+    }
+}

app/src/main/java/com/codigoparallevar/minicards/rendering/MyGLSurfaceView.java

@@ -0,0 +1,20 @@
+package com.codigoparallevar.minicards.rendering;
+
+import android.content.Context;
+import android.opengl.GLSurfaceView;
+
+public class MyGLSurfaceView extends GLSurfaceView {
+
+    private final MyGlRenderer mRenderer;
+
+    public MyGLSurfaceView(Context context) {
+        super(context);
+
+        setEGLContextClientVersion(2);
+
+        mRenderer = new MyGlRenderer();
+
+        setRenderer(mRenderer);
+        setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
+    }
+}

app/src/main/java/com/codigoparallevar/minicards/rendering/MyGlRenderer.java

@@ -0,0 +1,45 @@
+package com.codigoparallevar.minicards.rendering;
+
+import android.opengl.GLES20;
+import android.opengl.GLSurfaceView;
+import android.util.Log;
+
+import javax.microedition.khronos.egl.EGLConfig;
+import javax.microedition.khronos.opengles.GL10;
+
+class MyGlRenderer implements GLSurfaceView.Renderer {
+
+    private Triangle mTriangle;
+    private Square mSquare;
+
+    @Override
+    public void onSurfaceCreated(GL10 gl10, EGLConfig eglConfig) {
+        GLES20.glClearColor(0.75f, 0.81f, 1.0f, 1.0f);
+
+        mTriangle = new Triangle();
+        mSquare = new Square();
+    }
+
+    @Override
+    public void onSurfaceChanged(GL10 gl10, int width, int height) {
+        GLES20.glViewport(0, 0, width, height);
+    }
+
+    @Override
+    public void onDrawFrame(GL10 gl10) {
+        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
+        mTriangle.draw();
+    }
+
+    public static int loadShader(int type, String shaderCode){
+        // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
+        // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
+        int shader = GLES20.glCreateShader(type);
+
+        // add the source code to the shader and compile it
+        GLES20.glShaderSource(shader, shaderCode);
+        GLES20.glCompileShader(shader);
+
+        return shader;
+    }
+}

app/src/main/java/com/codigoparallevar/minicards/rendering/Square.java

@@ -0,0 +1,67 @@
+package com.codigoparallevar.minicards.rendering;
+
+import android.opengl.GLES20;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.FloatBuffer;
+import java.nio.ShortBuffer;
+import java.sql.SQLInvalidAuthorizationSpecException;
+
+public class Square {
+
+    private final String vertexShaderCode =
+            "attribute vec4 vPosition;" +
+                    "void main(){" +
+                    "gl_Position = vPosition;" +
+                    "}";
+
+    private final String fragmentShaderCode =
+            "precision medium float;" +
+                    "uniform vec4 vColor;" +
+                    "void main(){" +
+                    "gl_FragColor = vColor;" +
+                    "}";
+    private final int mProgram;
+
+
+    private FloatBuffer vertexBuffer;
+    private ShortBuffer drawListBuffer;
+
+    static final int COORDS_PER_VERTEX = 3;
+    static float squareCoords[] = {
+            -0.5f,  0.5f, 0.0f,   // top left
+            -0.5f, -0.5f, 0.0f,   // bottom left
+             0.5f, -0.5f, 0.0f,   // bottom right
+             0.5f,  0.5f, 0.0f,   // top right
+    };
+
+    private short drawOrder[] = { 0, 1, 2, 0, 2, 3 }; // order to draw vertices
+
+    public Square(){
+        ByteBuffer bb = ByteBuffer.allocateDirect(squareCoords.length * 4);
+        bb.order(ByteOrder.nativeOrder());
+
+        vertexBuffer = bb.asFloatBuffer();
+        vertexBuffer.put(squareCoords);
+        vertexBuffer.position(0);
+
+        ByteBuffer dlb = ByteBuffer.allocateDirect(drawOrder.length * 2);
+        dlb.order(ByteOrder.nativeOrder());
+        drawListBuffer = dlb.asShortBuffer();
+        drawListBuffer.put(drawOrder);
+        drawListBuffer.position(0);
+
+
+        int vertexShader = MyGlRenderer.loadShader(GLES20.GL_VERTEX_SHADER,
+                vertexShaderCode);
+        int fragmentShader = MyGlRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER,
+                fragmentShaderCode);
+
+        mProgram = GLES20.glCreateProgram();
+        GLES20.glAttachShader(mProgram, vertexShader);
+        GLES20.glAttachShader(mProgram, fragmentShader);
+
+        GLES20.glLinkProgram(mProgram);
+    }
+}

app/src/main/java/com/codigoparallevar/minicards/rendering/Triangle.java

@@ -0,0 +1,80 @@
+package com.codigoparallevar.minicards.rendering;
+
+import android.opengl.GLES20;
+import android.util.Log;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.FloatBuffer;
+
+public class Triangle {
+
+    private final String vertexShaderCode =
+            "attribute vec4 vPosition;" +
+            "void main(){" +
+                "gl_Position = vPosition;" +
+            "}";
+
+    private final String fragmentShaderCode =
+            "precision mediump float;" +
+            "uniform vec4 vColor;" +
+            "void main(){" +
+                "gl_FragColor = vColor;" +
+            "}";
+
+    private FloatBuffer vertexBuffer;
+    private final int mProgram;
+
+    static final int COORDS_PER_VERTEX = 3;
+    static float triangleCoords[] = {
+             0.0f,  0.622008459f, 0.0f, // top
+            -0.5f, -0.311004243f, 0.0f, // bottom left
+             0.5f, -0.311004243f, 0.0f  // bottom right
+    };
+
+    // Set color with red, green, blue and alpha (opacity) values
+    float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f };
+    private int mPositionHandle;
+    private int mColorHandle;
+
+    private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX;
+    private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex
+
+    public Triangle(){
+        ByteBuffer bb = ByteBuffer.allocateDirect(triangleCoords.length * 4);
+        bb.order(ByteOrder.nativeOrder());
+
+        vertexBuffer = bb.asFloatBuffer();
+        vertexBuffer.put(triangleCoords);
+        vertexBuffer.position(0);
+
+        int vertexShader = MyGlRenderer.loadShader(GLES20.GL_VERTEX_SHADER,
+                                                   vertexShaderCode);
+        int fragmentShader = MyGlRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER,
+                                                     fragmentShaderCode);
+
+        mProgram = GLES20.glCreateProgram();
+        GLES20.glAttachShader(mProgram, vertexShader);
+        GLES20.glAttachShader(mProgram, fragmentShader);
+
+        GLES20.glLinkProgram(mProgram);
+    }
+
+    public void draw(){
+        GLES20.glUseProgram(mProgram);
+
+        mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
+        GLES20.glEnableVertexAttribArray(mPositionHandle);
+
+        GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,
+                                     GLES20.GL_FLOAT, false,
+                                     vertexStride, vertexBuffer);
+
+        mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");
+
+        GLES20.glUniform4fv(mColorHandle, 1, color, 0);
+        Log.d("Triangle", "VB "+ vertexBuffer.get(1));
+        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);
+        GLES20.glDisableVertexAttribArray(mPositionHandle);
+    }
+}

app/src/main/res/layout/activity_test.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context="com.codigoparallevar.minicards.TestActivity">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Hello World!"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintLeft_toLeftOf="parent"
+        app:layout_constraintRight_toRightOf="parent"
+        app:layout_constraintTop_toTopOf="parent" />
+
+</android.support.constraint.ConstraintLayout>

app/src/main/res/values/colors.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="colorPrimary">#3F51B5</color>
+    <color name="colorPrimaryDark">#303F9F</color>
+    <color name="colorAccent">#FF4081</color>
+</resources>

app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">mini-cards</string>
+</resources>

app/src/main/res/values/styles.xml

@@ -0,0 +1,11 @@
+<resources>
+
+    <!-- Base application theme. -->
+    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+        <!-- Customize your theme here. -->
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+    </style>
+
+</resources>

app/src/test/java/com/codigoparallevar/minicards/ExampleUnitTest.java

@@ -0,0 +1,17 @@
+package com.codigoparallevar.minicards;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+public class ExampleUnitTest {
+    @Test
+    public void addition_isCorrect() throws Exception {
+        assertEquals(4, 2 + 2);
+    }
+}