| /* |
| * 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); |
| } |
| |
| } |