webgl-framework VS webgl-mountains

After the terrain we draw a sky hemisphere object with the basic DiffuseShader, and then draw 11 cloud sprites. Then we draw a sun sprite. These transparent objects are rendered without writing to the depth buffer. Clouds and sun have trimmed geometries for less overdraw. You can read about this optimized sprites technique here. We decided not to use soft particles for clouds because scene size allowed us to place them so that they don’t intersect with other geometries while still partially occluding some peaks. Not using soft particles is beneficial for performance because they require additional render pass to render scene depth.

Historically, the web demo was created first — it was used as a prototyping playground to compose a scene and to fine-tune shaders. Also, this really helps in sharing work between a team of two people without necessity to learn Android Studio for both. And when everything was polished and looked good enough, an Android app was created quite fast based on the web demo code. Porting code to Android is a quite straightforward and easy process because our WebGL framework has the same method signatures as the framework used in Android apps.

During development on PC everything was fine, but testing on different mobile phones with various GPUs revealed noticeable visual differences in hardware FP16 texture filtering. I suspect that the ANGLE wrapper for WebGL always uses full-precision floating point values in both shaders and textures, because we’ve already encountered precision issues in shader calculations during development of the Iceland WebGL demo - they were seen only on mobile devices with native WebGL-to-OpenGL ES translation.

Full source code is available on GitHub here and the live demo page is here. Click on the scene to change time of day (it may take a couple seconds to load textures), and by pressing Enter you can enter free-camera mode. Press and hold the right mouse button to look, and use WASD to move around.