1 /*
2  * Copyright (C) 2011 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package com.example.android.opengl;
17 
18 import javax.microedition.khronos.egl.EGLConfig;
19 import javax.microedition.khronos.opengles.GL10;
20 
21 import android.opengl.GLES20;
22 import android.opengl.GLSurfaceView;
23 import android.opengl.Matrix;
24 import android.util.Log;
25 
26 /**
27  * Provides drawing instructions for a GLSurfaceView object. This class
28  * must override the OpenGL ES drawing lifecycle methods:
29  * <ul>
30  *   <li>{@link android.opengl.GLSurfaceView.Renderer#onSurfaceCreated}</li>
31  *   <li>{@link android.opengl.GLSurfaceView.Renderer#onDrawFrame}</li>
32  *   <li>{@link android.opengl.GLSurfaceView.Renderer#onSurfaceChanged}</li>
33  * </ul>
34  */
35 public class MyGLRenderer implements GLSurfaceView.Renderer {
36 
37     private static final String TAG = "MyGLRenderer";
38     private Triangle mTriangle;
39     private Square   mSquare;
40 
41     // mMVPMatrix is an abbreviation for "Model View Projection Matrix"
42     private final float[] mMVPMatrix = new float[16];
43     private final float[] mProjectionMatrix = new float[16];
44     private final float[] mViewMatrix = new float[16];
45     private final float[] mRotationMatrix = new float[16];
46 
47     private float mAngle;
48 
49     @Override
onSurfaceCreated(GL10 unused, EGLConfig config)50     public void onSurfaceCreated(GL10 unused, EGLConfig config) {
51 
52         // Set the background frame color
53         GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
54 
55         mTriangle = new Triangle();
56         mSquare   = new Square();
57     }
58 
59     @Override
onDrawFrame(GL10 unused)60     public void onDrawFrame(GL10 unused) {
61         float[] scratch = new float[16];
62 
63         // Draw background color
64         GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
65 
66         // Set the camera position (View matrix)
67         Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
68 
69         // Calculate the projection and view transformation
70         Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);
71 
72         // Draw square
73         mSquare.draw(mMVPMatrix);
74 
75         // Create a rotation for the triangle
76 
77         // Use the following code to generate constant rotation.
78         // Leave this code out when using TouchEvents.
79         // long time = SystemClock.uptimeMillis() % 4000L;
80         // float angle = 0.090f * ((int) time);
81 
82         Matrix.setRotateM(mRotationMatrix, 0, mAngle, 0, 0, 1.0f);
83 
84         // Combine the rotation matrix with the projection and camera view
85         // Note that the mMVPMatrix factor *must be first* in order
86         // for the matrix multiplication product to be correct.
87         Matrix.multiplyMM(scratch, 0, mMVPMatrix, 0, mRotationMatrix, 0);
88 
89         // Draw triangle
90         mTriangle.draw(scratch);
91     }
92 
93     @Override
onSurfaceChanged(GL10 unused, int width, int height)94     public void onSurfaceChanged(GL10 unused, int width, int height) {
95         // Adjust the viewport based on geometry changes,
96         // such as screen rotation
97         GLES20.glViewport(0, 0, width, height);
98 
99         float ratio = (float) width / height;
100 
101         // this projection matrix is applied to object coordinates
102         // in the onDrawFrame() method
103         Matrix.frustumM(mProjectionMatrix, 0, -ratio, ratio, -1, 1, 3, 7);
104 
105     }
106 
107     /**
108      * Utility method for compiling a OpenGL shader.
109      *
110      * <p><strong>Note:</strong> When developing shaders, use the checkGlError()
111      * method to debug shader coding errors.</p>
112      *
113      * @param type - Vertex or fragment shader type.
114      * @param shaderCode - String containing the shader code.
115      * @return - Returns an id for the shader.
116      */
loadShader(int type, String shaderCode)117     public static int loadShader(int type, String shaderCode){
118 
119         // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
120         // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
121         int shader = GLES20.glCreateShader(type);
122 
123         // add the source code to the shader and compile it
124         GLES20.glShaderSource(shader, shaderCode);
125         GLES20.glCompileShader(shader);
126 
127         return shader;
128     }
129 
130     /**
131     * Utility method for debugging OpenGL calls. Provide the name of the call
132     * just after making it:
133     *
134     * <pre>
135     * mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor");
136     * MyGLRenderer.checkGlError("glGetUniformLocation");</pre>
137     *
138     * If the operation is not successful, the check throws an error.
139     *
140     * @param glOperation - Name of the OpenGL call to check.
141     */
checkGlError(String glOperation)142     public static void checkGlError(String glOperation) {
143         int error;
144         while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
145             Log.e(TAG, glOperation + ": glError " + error);
146             throw new RuntimeException(glOperation + ": glError " + error);
147         }
148     }
149 
150     /**
151      * Returns the rotation angle of the triangle shape (mTriangle).
152      *
153      * @return - A float representing the rotation angle.
154      */
getAngle()155     public float getAngle() {
156         return mAngle;
157     }
158 
159     /**
160      * Sets the rotation angle of the triangle shape (mTriangle).
161      */
setAngle(float angle)162     public void setAngle(float angle) {
163         mAngle = angle;
164     }
165 
166 }