Hi, I've spent a full day trying to draw a series of points using GL_POINTS. I know i could use a texture, but i want to learn how to draw points. The resulting image (zoomed) is shown here:
The code is written below. Any help on why are only 4 points appearing is greatly appreciated. <https://lh5.googleusercontent.com/-lelPSZoY4dw/UEIH5mVQfII/AAAAAAAAAD4/o5q5GMFuL00/s1600/points.png> public class MainActivity extends Activity { class MyGLSurfaceView extends GLSurfaceView { public MyGLSurfaceView(Context context) { super(context); setEGLContextClientVersion(2); // Create an OpenGL ES 2.0 context. setEGLConfigChooser(8, 8, 8, 8, 0, 0); getHolder().setFormat(PixelFormat.RGBA_8888); setRenderer(new MyGLRenderer()); // Set the Renderer for drawing on the GLSurfaceView // setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY); // Render the view only when there is a change in the drawing data (must be after setRenderer!) } } public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new MyGLSurfaceView(this)); } } class MyGLRenderer implements GLSurfaceView.Renderer { byte[][] bitmap = { {1,1,1,1,1,1,1,1}, {1,0,0,1,1,0,0,1}, {1,0,0,1,1,0,0,1}, {1,0,0,1,1,0,0,1}, {1,0,0,1,1,0,0,1}, {1,0,0,1,1,0,0,1}, {1,0,0,1,1,0,0,1}, {1,0,0,1,1,0,0,1}, {1,1,1,1,1,1,1,1}}; static final int COORDS_PER_VERTEX = 3; // Set color with red, green, blue and alpha (opacity) values float color[] = { 0,0,0, 1.0f }; float coords[] = new float[4 * COORDS_PER_VERTEX]; int w,h; public void onSurfaceCreated(GL10 unused, EGLConfig config) { } public void onDrawFrame(GL10 unused) { try { drawText(); } catch (Exception e) {debug(e.getMessage());} } private String vertexShaderCode(int w, int h) { return // http://www.songho.ca/opengl/gl_projectionmatrix.html "attribute vec4 vPosition;" + "mat4 projectionMatrix = mat4( 2.0/"+w+".0, 0.0, 0.0, -1.0,"+ "0.0, -2.0/"+h+".0, 0.0, 1.0,"+ "0.0, 0.0, -1.0, 0.0,"+ "0.0, 0.0, 0.0, 1.0);"+ "void main() {gl_Position = vPosition*projectionMatrix;}"; // the matrix must be included as a modifier of gl_Position } private final String fragmentShaderCode = "precision mediump float;" + "uniform vec4 vColor;" + "void main() {gl_FragColor = vColor;}"; private int mProgram; private int mPositionHandle; private int mColorHandle; public void onSurfaceChanged(GL10 unused, int width, int height) { w = width; h = height; // Adjust the viewport based on geometry changes, such as screen rotation GLES20.glViewport(0, 0, width, height); // prepare shaders and OpenGL program int vertexShader = MyGLRenderer.loadShader(GLES20.GL_VERTEX_SHADER,vertexShaderCode(width,height)); 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 GLES20.glUseProgram(mProgram); // Add program to OpenGL environment // get handle to fragment shader's vColor member mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor"); mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition"); // get handle to vertex shader's vPosition member GLES20.glEnableVertexAttribArray(mPositionHandle); // Enable a handle to the vertices - since this is the only one used, keep it enabled all the time } float[] letter; int nletter; private FloatBuffer letBuffer; private void drawText() { setColor(0xFF00FFFF); if (letter == null) { letter = new float[200]; for (int i = 0; i < bitmap.length; i++) { byte[]b = bitmap[i]; for (int j = 0; j < b.length; j++) if (b[j] == 1) { letter[nletter++] = j; letter[nletter++] = i; nletter++; } } ByteBuffer bb = ByteBuffer.allocateDirect(nletter * 4); // (# of coordinate values * 4 bytes per float) bb.order(ByteOrder.nativeOrder()); letBuffer = bb.asFloatBuffer(); letBuffer.put(letter,0,nletter); letBuffer.position(0); } int nn = nletter/3; GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, COORDS_PER_VERTEX * nn, letBuffer); GLES20.glDrawArrays(GLES20.GL_POINTS, 0,nn); } public static int loadShader(int type, String shaderCode) { int shader = GLES20.glCreateShader(type); GLES20.glShaderSource(shader, shaderCode); GLES20.glCompileShader(shader); return shader; } public void setColor(int rgb) { color[0] = (float)((rgb >> 16 ) & 0xFF) / 255f; color[1] = (float)((rgb >> 8 ) & 0xFF) / 255f; color[2] = (float)((rgb ) & 0xFF) / 255f; color[3] = (float)((rgb >>> 24) & 0xFF) / 255f; GLES20.glUniform4fv(mColorHandle, 1, color, 0); // Set color for drawing the line } } thanks, guich <https://lh5.googleusercontent.com/-lelPSZoY4dw/UEIH5mVQfII/AAAAAAAAAD4/o5q5GMFuL00/s1600/points.png> -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
