Sample code for OpenGL Android training class

( Original Id: Ib1650025a3c4b018c60d70ede3f25113660f68d8 )

Change-Id: I1d760b75d1f2bfe1ec90c71471867577bd146241

1 files changed, 141 insertions, 0 deletions

diff --git a/samples/OpenGL/HelloOpenGLES20/src/com/example/android/opengl/Triangle.java b/samples/OpenGL/HelloOpenGLES20/src/com/example/android/opengl/Triangle.java
new file mode 100644
index 000000000..8359b45e1
--- /dev/null
+++ b/samples/OpenGL/HelloOpenGLES20/src/com/example/android/opengl/Triangle.java
@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.opengl;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.FloatBuffer;
+
+import android.opengl.GLES20;
+
+/**
+ * A two-dimensional triangle for use as a drawn object in OpenGL ES 2.0.
+ */
+public class Triangle {
+
+    private final String vertexShaderCode =
+            // This matrix member variable provides a hook to manipulate
+            // the coordinates of the objects that use this vertex shader
+            "uniform mat4 uMVPMatrix;" +
+            "attribute vec4 vPosition;" +
+            "void main() {" +
+            // the matrix must be included as a modifier of gl_Position
+            // Note that the uMVPMatrix factor *must be first* in order
+            // for the matrix multiplication product to be correct.
+            "  gl_Position = uMVPMatrix * vPosition;" +
+            "}";
+
+    private final String fragmentShaderCode =
+            "precision mediump float;" +
+            "uniform vec4 vColor;" +
+            "void main() {" +
+            "  gl_FragColor = vColor;" +
+            "}";
+
+    private final FloatBuffer vertexBuffer;
+    private final int mProgram;
+    private int mPositionHandle;
+    private int mColorHandle;
+    private int mMVPMatrixHandle;
+
+    // number of coordinates per vertex in this array
+    static final int COORDS_PER_VERTEX = 3;
+    static float triangleCoords[] = {
+            // in counterclockwise order:
+            0.0f,  0.622008459f, 0.0f,   // top
+           -0.5f, -0.311004243f, 0.0f,   // bottom left
+            0.5f, -0.311004243f, 0.0f    // bottom right
+    };
+    private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX;
+    private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex
+
+    float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 0.0f };
+
+    /**
+     * Sets up the drawing object data for use in an OpenGL ES context.
+     */
+    public Triangle() {
+        // initialize vertex byte buffer for shape coordinates
+        ByteBuffer bb = ByteBuffer.allocateDirect(
+                // (number of coordinate values * 4 bytes per float)
+                triangleCoords.length * 4);
+        // use the device hardware's native byte order
+        bb.order(ByteOrder.nativeOrder());
+
+        // create a floating point buffer from the ByteBuffer
+        vertexBuffer = bb.asFloatBuffer();
+        // add the coordinates to the FloatBuffer
+        vertexBuffer.put(triangleCoords);
+        // set the buffer to read the first coordinate
+        vertexBuffer.position(0);
+
+        // prepare shaders and OpenGL program
+        int vertexShader = MyGLRenderer.loadShader(
+                GLES20.GL_VERTEX_SHADER, vertexShaderCode);
+        int fragmentShader = MyGLRenderer.loadShader(
+                GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
+
+        mProgram = GLES20.glCreateProgram();             // create empty OpenGL Program
+        GLES20.glAttachShader(mProgram, vertexShader);   // add the vertex shader to program
+        GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program
+        GLES20.glLinkProgram(mProgram);                  // create OpenGL program executables
+
+    }
+
+    /**
+     * Encapsulates the OpenGL ES instructions for drawing this shape.
+     *
+     * @param mvpMatrix - The Model View Project matrix in which to draw
+     * this shape.
+     */
+    public void draw(float[] mvpMatrix) {
+        // Add program to OpenGL environment
+        GLES20.glUseProgram(mProgram);
+
+        // get handle to vertex shader's vPosition member
+        mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
+
+        // Enable a handle to the triangle vertices
+        GLES20.glEnableVertexAttribArray(mPositionHandle);
+
+        // Prepare the triangle coordinate data
+        GLES20.glVertexAttribPointer(
+                mPositionHandle, COORDS_PER_VERTEX,
+                GLES20.GL_FLOAT, false,
+                vertexStride, vertexBuffer);
+
+        // get handle to fragment shader's vColor member
+        mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");
+
+        // Set color for drawing the triangle
+        GLES20.glUniform4fv(mColorHandle, 1, color, 0);
+
+        // get handle to shape's transformation matrix
+        mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
+        MyGLRenderer.checkGlError("glGetUniformLocation");
+
+        // Apply the projection and view transformation
+        GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mvpMatrix, 0);
+        MyGLRenderer.checkGlError("glUniformMatrix4fv");
+
+        // Draw the triangle
+        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount);
+
+        // Disable vertex array
+        GLES20.glDisableVertexAttribArray(mPositionHandle);
+    }
+
+}