Error Openeng GL 2.0 Android 0x501 (GL_INVALID_VALUE)

Question

I am trying to create a small Open GL2.0 demo application on Android, but I am getting the following errors.

in log cat

07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 07-02 20:50:40.110: E/libEGL(1252): call to OpenGL ES API with no current context (logged once per thread) 

in console

 [2012-07-02 20:50:44 - Emulator] development/tools/emulator/opengl/host/libs/Translator/GLES_V2/GLESv2Imp.cpp:glGetAttribLoc ation:826 error 0x501 [2012-07-02 20:50:44 - Emulator] development/tools/emulator/opengl/host/libs/Translator/GLES_V2/GLESv2Imp.cpp:glGetUniformLocation:1383 error 0x501 

my code

View

 package limitliss.graphics.play; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; import android.content.Context; import android.opengl.GLES20; import android.opengl.GLSurfaceView; import android.opengl.GLSurfaceView.Renderer; import android.opengl.GLU; public class OGLView extends GLSurfaceView implements Renderer { private int mColorType = 0; private float rotx = 0.0f; private float roty = 0.0f; Triangle tri = new Triangle(); public OGLView(Context context) { super(context); setEGLContextClientVersion(2); this.setRenderer(this); setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY); // TODO Auto-generated constructor stub } 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 onSurfaceCreated(GL10 unused, EGLConfig config) { // Set the background frame color GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f); tri.draw(); } public void onDrawFrame(GL10 unused) { // Redraw background color GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT); tri.draw(); } public void onSurfaceChanged(GL10 unused, int width, int height) { GLES20.glViewport(0, 0, width, height); } } Triangle package limitliss.graphics.play; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import javax.microedition.khronos.opengles.GL10; import android.opengl.GLES20; public class Triangle { float color[] = { 0.63671875f, 0.76953125f, 0.22265625f, 1.0f }; private FloatBuffer vertexBuffer; int mProgram; int mPositionHandle; 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;" + "}"; // 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 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 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); int vertexShader = OGLView.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode); int fragmentShader = OGLView.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode); mProgram = GLES20.glCreateProgram(); // create empty OpenGL ES Program GLES20.glAttachShader(mProgram, vertexShader); // add the vertex shader to program GLES20.glAttachShader(mProgram, fragmentShader); // add the fragment shader to program GLES20.glLinkProgram(mProgram); } public void draw() { // Add program to OpenGL ES environment GLES20.glUseProgram(mProgram); // get handle to vertex shader 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, COORDS_PER_VERTEX, vertexBuffer); // get handle to fragment shader vColor member int 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, 3); // Disable vertex array GLES20.glDisableVertexAttribArray(mPositionHandle); } public void render(GL10 gl){ gl.glPushMatrix(); gl.glColor4f(this.color[0],this.color[1],this.color[2],this.color[3]); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glDrawArrays(GL10.GL_TRIANGLE_FAN, 0, 3); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glPopMatrix(); } } 

Answer 1

You get call to OpenGL ES API with no current context errors call to OpenGL ES API with no current context because you create your triangle Triangle tri = new Triangle(); outside the OpenGL thread (and the triangle constructor makes opengl calls). In the opengl thread, only code is executed inside OpenGL callbacks (onSurfaceCreated, onDrawFrame, etc.).

Put tri = new Triangle() inside onSurfaceCreated and these errors should onSurfaceCreated away.

Answer 2

add a closed final context context; just below "the open class OGLView extends GLSurfaceView implements Renderer {"