/*
* Copyright (C) 2014 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.google.android.glass.sample.apidemo.opengl;
import android.opengl.GLES20;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
/**
* Renders a 3D Cube using OpenGL ES 2.0.
*
* For more information on how to use OpenGL ES 2.0 on Android, see the
* <a href="//developer.android.com/training/graphics/opengl/index.html">
* Displaying Graphics with OpenGL ES</a> developer guide.
*/
public class Cube {
/** Cube vertices */
private static final float VERTICES[] = {
-0.5f, -0.5f, -0.5f,
0.5f, -0.5f, -0.5f,
0.5f, 0.5f, -0.5f,
-0.5f, 0.5f, -0.5f,
-0.5f, -0.5f, 0.5f,
0.5f, -0.5f, 0.5f,
0.5f, 0.5f, 0.5f,
-0.5f, 0.5f, 0.5f
};
/** Vertex colors. */
private static final float COLORS[] = {
0.0f, 1.0f, 1.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
1.0f, 0.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 1.0f, 1.0f,
};
/** Order to draw vertices as triangles. */
private static final byte INDICES[] = {
0, 1, 3, 3, 1, 2, // Front face.
0, 1, 4, 4, 5, 1, // Bottom face.
1, 2, 5, 5, 6, 2, // Right face.
2, 3, 6, 6, 7, 3, // Top face.
3, 7, 4, 4, 3, 0, // Left face.
4, 5, 7, 7, 6, 5, // Rear face.
};
/** Number of coordinates per vertex in {@link VERTICES}. */
private static final int COORDS_PER_VERTEX = 3;
/** Number of values per colors in {@link COLORS}. */
private static final int VALUES_PER_COLOR = 4;
/** Vertex size in bytes. */
private final int VERTEX_STRIDE = COORDS_PER_VERTEX * 4;
/** Color size in bytes. */
private final int COLOR_STRIDE = VALUES_PER_COLOR * 4;
/** Shader code for the vertex. */
private static final String VERTEX_SHADER_CODE =
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"attribute vec4 vColor;" +
"varying vec4 _vColor;" +
"void main() {" +
" _vColor = vColor;" +
" gl_Position = uMVPMatrix * vPosition;" +
"}";
/** Shader code for the fragment. */
private static final String FRAGMENT_SHADER_CODE =
"precision mediump float;" +
"varying vec4 _vColor;" +
"void main() {" +
" gl_FragColor = _vColor;" +
"}";
private final FloatBuffer mVertexBuffer;
private final FloatBuffer mColorBuffer;
private final ByteBuffer mIndexBuffer;
private final int mProgram;
private final int mPositionHandle;
private final int mColorHandle;
private final int mMVPMatrixHandle;
public Cube() {
ByteBuffer byteBuffer = ByteBuffer.allocateDirect(VERTICES.length * 4);
byteBuffer.order(ByteOrder.nativeOrder());
mVertexBuffer = byteBuffer.asFloatBuffer();
mVertexBuffer.put(VERTICES);
mVertexBuffer.position(0);
byteBuffer = ByteBuffer.allocateDirect(COLORS.length * 4);
byteBuffer.order(ByteOrder.nativeOrder());
mColorBuffer = byteBuffer.asFloatBuffer();
mColorBuffer.put(COLORS);
mColorBuffer.position(0);
mIndexBuffer = ByteBuffer.allocateDirect(INDICES.length);
mIndexBuffer.put(INDICES);
mIndexBuffer.position(0);
mProgram = GLES20.glCreateProgram();
GLES20.glAttachShader(mProgram, loadShader(GLES20.GL_VERTEX_SHADER, VERTEX_SHADER_CODE));
GLES20.glAttachShader(
mProgram, loadShader(GLES20.GL_FRAGMENT_SHADER, FRAGMENT_SHADER_CODE));
GLES20.glLinkProgram(mProgram);
mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
mColorHandle = GLES20.glGetAttribLocation(mProgram, "vColor");
mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
}
/**
* 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);
// Prepare the cube coordinate data.
GLES20.glEnableVertexAttribArray(mPositionHandle);
GLES20.glVertexAttribPointer(
mPositionHandle, 3, GLES20.GL_FLOAT, false, VERTEX_STRIDE, mVertexBuffer);
// Prepare the cube color data.
GLES20.glEnableVertexAttribArray(mColorHandle);
GLES20.glVertexAttribPointer(
mColorHandle, 4, GLES20.GL_FLOAT, false, COLOR_STRIDE, mColorBuffer);
// Apply the projection and view transformation.
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mvpMatrix, 0);
// Draw the cube.
GLES20.glDrawElements(
GLES20.GL_TRIANGLES, INDICES.length, GLES20.GL_UNSIGNED_BYTE, mIndexBuffer);
// Disable vertex arrays.
GLES20.glDisableVertexAttribArray(mPositionHandle);
GLES20.glDisableVertexAttribArray(mColorHandle);
}
/** Loads the provided shader in the program. */
private static int loadShader(int type, String shaderCode){
int shader = GLES20.glCreateShader(type);
GLES20.glShaderSource(shader, shaderCode);
GLES20.glCompileShader(shader);
return shader;
}
}