Lecture 8 - OpenGL on Android

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OpenGL ES

 Cut down version of OpenGL  Fixed point support  Found in many mobile platforms (Android, iOS, Blackberry, Symbian, 3DS, etc.)  Designed for slower GPUs and CPUs Laura Gheorghe, Petre Eftime 2

Version 1.x

 OpenGL ES 1.0 based on OpenGL 1.3 and OpenGL ES 1.1 based on OpenGL 1.5

 Common and Common-Lite (only fixed point) profile  Fixed-function rendering pipeline  Reduced features: no quad and polygon primitives, no stippling, only multisample AA, reduced drawing modes, no display lists, etc.

 OpenGL ES 1.1 adds better multitexture support, VBOs, clip planes, mipmap generation  Android 1.0 and higher Laura Gheorghe, Petre Eftime 3

Version 2.0

 Based on OpenGL 2.0, but reduced fixed-function pipeline support  Not compatible with OpenGL ES 1.x

 OpenGL ES Shading Language  ESSL only has forward branches and fixed iteration loops  Transforming and Lighting functions replaced by shaders  Better performance than OpenGL ES 1.x in many cases  Android 2.2 and higher Laura Gheorghe, Petre Eftime 4

Version 3.0

 Compatible with OpenGL ES 2.0 and OpenGL 4.3

 Standardized texture compression  Better texturing support  New Shading Language version with full support for integer and floating point  Improved flow control  Easier portability  Android 4.3 and higher Laura Gheorghe, Petre Eftime 5

GL Surface

 Manages a surface (a region of memory which can be displayed on screen)  Manages an EGL display (an OpenGL rendering context)  Dedicated rendering thread  Can provide debug information Laura Gheorghe, Petre Eftime 6

EGL

 Virtual display which contains a rendering context  2D and 3D rendering  Allows having multiple smaller surfaces on the actual screen or drawing to offscreen buffer  Used by SurfaceFlinger and other compositors (Wayland, Mir) or libraries (SDL) Laura Gheorghe, Petre Eftime 7

Demo

 Create GL2JNIView and set it as a view for the activity  Constructor initializes the view private void init(boolean translucent, int depth, int stencil) { setEGLContextFactory(new ContextFactory()); setEGLConfigChooser( translucent ?

new ConfigChooser(8, 8, 8, 8, depth, stencil) : new ConfigChooser(5, 6, 5, 0, depth, stencil) ); setRenderer(new Renderer()); } Laura Gheorghe, Petre Eftime 8

}

Demo

public EGLConfig chooseConfig(EGL10 egl, EGLDisplay display) { /* Get the number of minimally matching EGL configurations */ int[] num_config = new int[1]; egl.eglChooseConfig(display, s_configAttribs2, null, 0, num_config); int numConfigs = num_config[0]; /* Allocate then read the array of minimally matching EGL configs */ EGLConfig[] configs = new EGLConfig[numConfigs]; egl.eglChooseConfig(display, s_configAttribs2, configs, numConfigs, num_config); /* Now return the "best" one (matches rgba specifications) */ return chooseConfig(egl, display, configs); Laura Gheorghe, Petre Eftime 9

Demo

private static class Renderer implements GLSurfaceView.Renderer { public void onDrawFrame(GL10 gl) { GL2JNILib.step(); } public void onSurfaceChanged(GL10 gl, int width, int height) { GL2JNILib.init(width, height); } public void onSurfaceCreated(GL10 gl, EGLConfig config) { // Do nothing.

} } Laura Gheorghe, Petre Eftime 10

Demo

 setupGraphics    Compiles vertex and pixel shaders into a program Defines Uniforms, Attributes, etc.

Sets initial camera position and viewport Laura Gheorghe, Petre Eftime 11

Demo

 renderFrame     Updates camera Sets shader program Sets Uniforms and Attributes for current frame Draws triangles Laura Gheorghe, Petre Eftime 12

Android Tools for Debugging and Profiling

 Logging  Debugging Developer Options: Overdraw, Clipping  Profiling Developer Options: Performance metrics on screen or through ADB, Traces  Tracer for OpenGL ES: Visualize traces Laura Gheorghe, Petre Eftime 13

Intel GPA

 Intel Atom processors  More information: GPU, CPU, Battery usage  More detailed analysis  Identifies possible bottlenecks  Realtime  Works over Wifi Laura Gheorghe, Petre Eftime 14

Vendor specific tools

 Low level information  Different interface and capabilities for each vendor  Optimizations not always portable  PowerVR, Tegra, Adreno, etc.

Laura Gheorghe, Petre Eftime 15

Bibliography

 https://www.khronos.org/opengles/  http://developer.android.com/guide/topics/graphics/ope ngl.html

 http://developer.android.com/training/graphics/opengl/i ndex.html

Laura Gheorghe, Petre Eftime 16

Keywords

 OpenGL  EGL  Fixed function pipeline  Shaders  GLSurfaceView  Profiling  Tracer Laura Gheorghe, Petre Eftime 17