Draw text in OpenGL ES (Android)

Rendering text to a texture is simpler than what the Sprite Text demo make it looks like, the basic idea is to use the Canvas class to render to a Bitmap and then pass the Bitmap to an OpenGL texture: // Create an empty, mutable bitmap Bitmap bitmap = Bitmap.createBitmap(256, 256, Bitmap.Config.ARGB_4444); // get a canvas to paint over the bitmap Canvas canvas = new Canvas(bitmap); bitmap.eraseColor(0); // get a background image from resources // note the image format must match the bitmap format Drawable background = context.getResources().getDrawable(R.drawable.background); background.setBounds(0, 0, 256, 256); background.draw(canvas); // draw the background to our bitmap // Draw the text Paint textPaint = new Paint(); textPaint.setTextSize(32); textPaint.setAntiAlias(true); textPaint.setARGB(0xff, 0x00, 0x00, 0x00); // draw the text centered canvas.drawText("Hello World", 16,112, textPaint); //Generate one texture pointer... gl.glGenTextures(1, textures, 0); //...and bind it to our array gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]); //Create Nearest Filtered Texture gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); //Different possible texture parameters, e.g. GL10.GL_CLAMP_TO_EDGE gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT); //Use the Android GLUtils to specify a two-dimensional texture image from our bitmap GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); //Clean up bitmap.recycle();

I looked at the sprite text example and it looks awfully complicated for such a task, I considered rendering to a texture too, but I'm worried about the performance hit that might cause. I might just have to go with a view instead and worry about porting when it's time to cross that bridge :)

Take a look at CBFG and the Android port of the loading/rendering code. You should be able to drop the code into your project and use it straight away. CBFG - http://www.codehead.co.uk/cbfg Android loader - http://www.codehead.co.uk/cbfg/TexFont.java

Look at the "Sprite Text" sample in the http://www.go-android.de/externe-news/introducing-glsurfaceview.

According to this link: http://code.neenbedankt.com/how-to-render-an-android-view-to-a-bitmap You can render any View to a bitmap. It's probably worth assuming that you can layout a view as you require (including text, images etc.) and then render it to a Bitmap. Using JVitela's code http://stackoverflow.com/questions/1339136/draw-text-in-opengl-es-android/4336679#4336679 you should be able to use that Bitmap as an OpenGL texture.

If you insist on using GL, you could render the text on to textures. Assuming that most of the HUD is relatively static, you shouldn't have to load the textures to texture memory too often.

How exactly did you overlay the textview? I have been following http://blog.jayway.com/2009/12/03/opengl-es-tutorial-for-android-part-i/ and cannot find any examples on how to overlay text continuing from these tutorials.

I have been looking for this for a few hours, this was the first article i came accross and although it has the best answer, the most popular answers i think are off the mark. Certainly for what i needed. weichsel's and shakazed's answers were right on the button but a bit obscured in the articles. To put you right to the project. Here: Just create a new Android project based on existing sample. Choose ApiDemos: Look under the source folder ApiDemos/src/com/example/android/apis/graphics/spritetext And you will find everything you need.