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POdrawing lines on Android with OpenGL ES 1.0
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  1. POdrawing lines on Android with OpenGL ES 1.0
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    copied!<p>The following code attempts to draw the frame of the GLSurfaceView and a diagonal line but the result is a big black screen instead. I try to set up orthonogal projection, align the viewport size to the View size, draw the frame lines with glDrawArrays() and the diagonal line with glDrawElements(). I couldn't find the source of the problem.</p> <pre><code>public class MapView extends GLSurfaceView implements Renderer { private int w, h; private FloatBuffer frameVertices; private ByteBuffer diagIndices; public MapView(Context ctx) { this(ctx, null); } public MapView(Context context, AttributeSet attrs) { super(context, attrs); setRenderer(this); } @Override public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT); gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glVertexPointer(2, GL10.GL_FLOAT, 0, frameVertices); gl.glColor4f(0f, 0f, 1f, 0.5f); gl.glDrawArrays(GL10.GL_LINE_LOOP, 0, 4); gl.glDrawElements(GL10.GL_LINES, 1, GL10.GL_UNSIGNED_BYTE, diagIndices); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); } @Override public void onSurfaceChanged(GL10 gl, int width, int height) { // TODO Auto-generated method stub } @Override public void onSurfaceCreated(GL10 gl, EGLConfig config) { w = getWidth(); h = getHeight(); TRC.debug("w = " + w + ", h = " + h); gl.glClearColor(0, 0, 0, 1); gl.glViewport(0, 0, w, h); gl.glDepthRangex(1, -1); // TODO remove gl.glMatrixMode(GL10.GL_PROJECTION); gl.glLoadIdentity(); gl.glOrthox(0, w, 0, h, 1, -1); float[] frame = { 0, 0, w-1, 0, w-1, h-1, 0, h-1 }; ByteBuffer byteBuffer = ByteBuffer.allocateDirect(frame.length * 4); byteBuffer.order(ByteOrder.nativeOrder()); frameVertices = byteBuffer.asFloatBuffer(); frameVertices.put(frame); frameVertices.flip(); frameVertices.position(0); gl.glLineWidthx(10); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glDisable(GL10.GL_DEPTH_TEST); diagIndices = ByteBuffer.allocateDirect(2); diagIndices.order(ByteOrder.nativeOrder()); diagIndices.put(new byte[] {0, 2}); diagIndices.flip(); } } </code></pre> <p>What can be the matter?</p>
 

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