Others have already pointed out problems, potential and verifiable.
But I am surprised no one has mentioned: your settings for glOrtho's
near_val and far_val are odd, to say the least. The default is exactly
the other way around with near_val=-1.0 and far_val=+1.0. Your values
put the near plane behind the viewer, but the far plane in front. Is
this really what you want?
On Aug 2, 8:47 pm, SChaser <crotalistig...@gmail.com> wrote:
> Source code is below.
>
> Robert Green provides some helpful information, for which I am
> thankful.
>
> However, I am not clear on two of the points.
>
> I currently have the situation where no lines at all show on the
> emulator (the background color does) and things work perfectly on the
> G1.
>
> On Aug 2, 11:26 am, Robert Green <rbgrn....@gmail.com> wrote:
> ....
>
> > 1) You are in a native resolution to the screen you're rendering on
> > (turn all the density and screen-size stuff on in the manifest to
> > avoid compat mode)
>
> Are these the attributes on the "support-screens" tag? I did not have
> that tag, but adding it and turning on all the attributes in the check-
> boxes did not solve the problem.
>
> > 2) You draw the lines centered on their pixel, so they look a half
> > pixel off.
> > -- To draw a horizontal line across the top row of pixels, you need to
> > make the line with 1.0f and have y be 0.5f (because it will draw from
> > 0 to 1 that way)
>
> I am drawing in fixed point projection(?) space, so the relationship
> of the lines to pixels is not clear. Also, I don't want to have to
> redraw the lines when the scale changes - I want to be able to zoom
> and pan easily. Is there a way to achieve that and have the lines
> show?
>
> > 3) Make sure you don't have any z-fighting. Drawing 2 things on the
> > exact same plane with depth-test turned on causes bad results on many
> > opengl implementations.
>
> Depth test turned off. I'm doing 2D only, so I think I'm clear there.
>
> Again, thanks for the help.
>
> ============ CODE SNIPS ==============
>
> ----- Create glSurfaceView -------
> private GLSurfaceView makeGLSurfaceView(GLSurfaceView.Renderer
> renderer, Context context) {
> GLSurfaceView view = new GLSurfaceView(context);
> view.setDebugFlags(GLSurfaceView.DEBUG_CHECK_GL_ERROR |
> GLSurfaceView.DEBUG_LOG_GL_CALLS);
> view.setEGLConfigChooser(false);
> if ( renderer != null ) {
> view.setRenderer(renderer);
> view.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
> }
> view.getHolder().setFormat(PixelFormat.OPAQUE);
> return view;
> } // make gl surface view
>
> ------------ onDrawFrame ----------
>
> // Everything stuffed into onDrawFrame to make it easy to read on
> forum
> @Override
> public void onDrawFrame(GL10 gl) {
> gl.glClearColor(0,0,.2f, 1f);
> gl.glDisable(GL10.GL_CULL_FACE);
> gl.glShadeModel(GL10.GL_FLAT);
> gl.glDisable(GL10.GL_DEPTH_TEST);
> gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
> gl.glMatrixMode(GL10.GL_PROJECTION);
> gl.glLoadIdentity();
> gl.glViewport(0, 0, MyApp._width, MyApp._height);
> gl.glEnable(GL10.GL_BLEND);
> gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
> gl.glEnable(GL10.GL_LINE_SMOOTH);
> gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
> _hgt2width = (float) MyApp._width / MyApp._height;
> gl.glOrthof(-_hgt2width, _hgt2width, -1, 1, 1, -1);
>
> gl.glScalef(1, _hgt2width, 1);
> gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
>
> float lscale = .002f*MyApp._curScale;
>
> gl.glPushMatrix();
> gl.glColor4f(1f, 1f, 0f, 1f);
>
> gl.glTranslatef(.375f, .5f, 0f);
> gl.glScalef( lscale, lscale, 1f);
> gl.glVertexPointer(2, GL10.GL_FIXED, 0, _lineVertices);
> gl.glLineWidthx(0x1);
> drawArrays(gl);
> gl.glPopMatrix();
>
> gl.glPushMatrix();
> gl.glColor4f(1f, 1f, 1f, 1.0f);
> gl.glScalef( lscale*8, lscale*8, 1f);
> gl.glVertexPointer(2, GL10.GL_FIXED, 0, _lineVertices);
> gl.glLineWidthx(0x1);
> drawArrays(gl);
> gl.glPopMatrix();
>
> }
> void drawArrays(GL10 gl) {
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 0, 5); //small square
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 5, 5); //medium square
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 10, 5);//large square
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 15, 2);//x axis
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 17, 2);//y axis
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 19, 2);//X half
> gl.glDrawArrays(GL10.GL_LINE_STRIP, 21, 2);//X half
> }
>
> void makeLines() {
> int hlf = 0x08000;
> int one = 0x10000+hlf;
> int sml = one/8;
> int ten = one;
> int big = 0x40000000;
> Log.d("===jrm", String.format("one:%x big:%x", one, big));
> int vertices[] = {
> -sml , sml, //0 start square - scale 1/10
> sml , sml, //1
> sml , -sml, //2
> -sml , -sml, //3
> -sml , sml, //4
>
> -one , one, //5 start square - scale 1
> one , one, //6
> one , -one, //7
> -one , -one, //8
> -one , one, //9
>
> -ten , ten, //10 start square - scale 10
> ten , ten, //11
> ten , -ten, //12
> -ten , -ten, //13
> -ten , ten, //14
>
> -big , 0, //15 start coord axes over huge area
> big , 0, //16
>
> 0 , big, //17
> 0 , -big, //18
>
> -big , -big, //19 start X over huge dimensions
> big , big, //20
>
> -big , big, //21
> big , -big, //22
> ten , one // BUT? Without this line, blows up
> if openGL debug is enabled
>
> };
> this.numLines = vertices.length/2;
>
> ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4);
> vbb.order(ByteOrder.nativeOrder());
> _lineVertices = vbb.asIntBuffer();
> _lineVertices.put(vertices);
> _lineVertices.position(0);
> }
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