I am trying to create a triangle in openGL 2.0 but some some reason background is shows up but no triangle. I am following this tutorial: Building an OpenGL ES Environment | Android Developers
i have the same code as on tutorial but for some reason the triangle is not showing up.
may be i missed some thing or i am doing some thing wrong?
i have two class.
GlRender.java
GLTriangle.java
public class GlRender implements Renderer { private GLTriangle glTriangleObj; private final float[] mModelMatrix = new float[16]; private final float[] mProjectionMatrix = new float[16]; private final float[] mViewMatrix = new float[16]; private final float[] mRotationMatrix = new float[16]; /************************/ /*** create() method ***/ /************************/ @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { // Set the background color // 0 to 1 // 1 = no transparent GLES20.glClearColor(0.8f, 0.2f, 0.2f, 1f); gl.glClearDepthf(1f); glTriangleObj = new GLTriangle(); // glSquare = new Square(); //etc... // postion the eye behind the origin final float eyeX = 0.0f; final float eyeY = 0.0f; final float eyeZ = 1.5f; // we are looking toward the distance final float lookX = 0.0f; final float lookY = 0.0f; final float lookZ = -5.0f; // Set our up vector. This is where our head would be pointing were we // holding the camera. final float upX = 0.0f; final float upY = 1.0f; final float upZ = 0.0f; // Set the view matrix. This matrix can be said to represent the camera // position. // NOTE: In OpenGL 1, a ModelView matrix is used, which is a combination // of a model and // view matrix. In OpenGL 2, we can keep track of these matrices // separately if we choose. Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ); } /********************/ /*** paint method ***/ /********************/ @Override public void onDrawFrame(GL10 gl) { // Redraw background color GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); // do a complete rotation every 10 seconds // long time = SystemClock.uptimeMillis() % 10000L; // float angleInDegree = (360.0f / 10000.0f) * ((int) time); // draw the triangle face straight on // Matrix.setIdentityM(mModelMatrix, 0); // Matrix.rotateM(mModelMatrix, 0, angleInDegree, 0.0f, 0.0f, 1.0f); // Set the camera position (View matrix) Matrix.setLookAtM(mViewMatrix, 0, 0, -2, 0, 0f, 0f, 0f, 0f, 2.0f, 0.0f); // Calculate the projection and view transformation Matrix.multiplyMM(mModelMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0); glTriangleObj.draw(mModelMatrix); } /*****************************/ /*** landscape to portrait ***/ /*****************************/ @Override public void onSurfaceChanged(GL10 gl, int width, int height) { if (height == 0) height = 1; // Set the OpenGL viewport to the same size as the surface. GLES20.glViewport(0, 0, width, height); // while the width will vary as per aspect ratio. final float ratio = (float) width / height; final float left = -ratio; final float right = ratio; final float bottom = -1.0f; final float top = 1.0f; final float near = 1.0f; final float far = 25.0f; Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far); } }
GLTriangle.java
public class GLTriangle { // always same 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;" + "}"; // always start at zero when ploting a point as defult // trinagle Coordinates - vertex = 3(x y z) private float trinagleCoords[] = { 0f, 1f, // V 0 - top 1f, -1, // V 1 - right bottom -1f, 1f // V 2 - left bottom }; private int COORDS_PER_VERTEX = 2; // number of points private FloatBuffer vertexBuffer; private short[] drawOrder = { 0, 1, 2 }; // order private ShortBuffer orderBuffer; float color[] = { 0.5f, 1f, 0f, 1f }; private int vertexCount = trinagleCoords.length / COORDS_PER_VERTEX; private int vertexStride = COORDS_PER_VERTEX * 4; // bytes per vertex // used to pass in the transformation matrix private final int mProgram; // used to pass in model poition information private int mPositionHandle; // used to pass inmodel color information private int mColorHandle; private int mMVPMatrixHandle; public GLTriangle() { // vertices - has to be 4 ByteBuffer byteBuffer = ByteBuffer .allocateDirect(trinagleCoords.length * 4); byteBuffer.order(ByteOrder.nativeOrder()); vertexBuffer = byteBuffer.asFloatBuffer(); vertexBuffer.put(trinagleCoords); vertexBuffer.position(0); // draw order - has to be 2 ByteBuffer pointByteBuffer = ByteBuffer .allocateDirect(drawOrder.length * 2); pointByteBuffer.order(ByteOrder.nativeOrder()); orderBuffer = pointByteBuffer.asShortBuffer(); orderBuffer.put(drawOrder); orderBuffer.position(0); // shader - always same int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode); int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode); // create empty OpenGL ES Program mProgram = GLES20.glCreateProgram(); // add the vertex shader to program GLES20.glAttachShader(mProgram, vertexShader); // add the fragment shader to program GLES20.glAttachShader(mProgram, fragmentShader); // creates OpenGL ES program executables GLES20.glLinkProgram(mProgram); } /************/ /*** same ***/ /************/ 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; } public void draw(float[] mModelMatrix) { // 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); // Draw the triangle GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount); // Disable vertex array GLES20.glDisableVertexAttribArray(mPositionHandle); // get handle to shape's transformation matrix mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix"); // Apply the projection and view transformation GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mModelMatrix, 0); // Draw the triangle GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount); ///// // Draw the square GLES20.glDrawElements(GLES20.GL_TRIANGLES, drawOrder.length, GLES20.GL_UNSIGNED_SHORT, orderBuffer); // Disable vertex array GLES20.glDisableVertexAttribArray(mPositionHandle); } }