This directory contains the host-side modules related to hardware OpenGL ES emulation. The guest-side modules are in $ANDROID_BUILD_TOP/development/tools/emulator/opengl. I. Overview of components: ========================== The 'emugen' tool is used to generate several source files related to the EGL/GLES command stream used between the guest and the host during emulation. host/tools/emugen -> emugen program Note that emugen is capable of generating, from a single set of specification files, three types of auto-generated sources: - sources to encode commands into a byte stream. - sources to decode the byte stream into commands. - sources to wrap normal procedural EGL/GLES calls into context-aware ones. Modules under the system/ directory corresponds to code that runs on the guest, and implement the marshalling of EGL/GLES commands into a stream of bytes sent to the host through a fast pipe mechanism. system/GLESv1_enc -> encoder for GLES 1.1 commands system/GLESv2_enc -> encoder for GLES 2.0 commands system/renderControl_enc -> encoder for rendering control commands system/egl -> emulator-specific guest EGL library system/GLESv1 -> emulator-specific guest GLES 1.1 library system/gralloc -> emulator-specific gralloc module system/OpenglSystemCommon -> library of common routines Modules under the host/ directory corresponds to code that runs on the host, and implement the decoding of the command stream, translation of EGL/GLES commands into desktop GL 2.0 ones, and rendering to an off-screen buffer. host/libs/GLESv1_dec -> decoder for GLES 1.1 commands host/libs/GLESv2_dec -> decoder for GLES 2.0 commands host/libs/renderControl_dec -> decoder for rendering control commands host/libs/Translator/EGL -> translator for EGL commands host/libs/Translator/GLES_CM -> translator for GLES 1.1 commands host/libs/Translator/GLES_V2 -> translator for GLES 2.0 commands host/libs/Translator/GLcommon -> library of common translation routines host/libs/libOpenglRender -> rendering library (uses all host libs above) can be used by the 'renderer' program below, or directly linked into the emulator UI program. host/renderer/ -> stand-alone renderer program executable. this can run in head-less mode and receive requests from several emulators at the same time. It is the receiving end of all command streams. Modules under the test/ directory correspond to test programs that are useful to debug the various modules described above: tests/EGL_host_wrapper -> a small library used to dynamically load the desktop libEGL.so or a replacement named by the ANDROID_EGL_LIB environment variable. This lib provides all EGL entry points. tests/emulator_test_renderer -> a small program to run the rendering library in a single SDL window on the host desktop. tests/gles_android_wrapper -> guest EGL / GLES libraries that are run on the device to run some tests. Replace the system/egl and system/GLESv1 modules for now. tests/translator_tests/GLES_CM -> desktop GLESv1 translation unit test tests/translator_tests/GLES_V2 -> desktop GLESv2 translation unit test tests/translator_tests/MacCommon -> used by translation tests on Mac only. tests/ut_rendercontrol_enc -> guest library used by tests/ut_renderer tests/ut_rendercontrol_dec -> host library used by tests/ut_renderer tests/ut_renderer -> unit-test for render control and rendering library. II. Build system considerations: -------------------------------- The dependencies on the more than 20 components described in the previous section are pretty sophisticated, involving lots of auto-generated code and non-trivial placement for guest/device libraries. To simplify the development and maintenance of these modules, a set of helper GNU Make function is defined in common.mk, and included from the Android.mk in this directory. These functions all begin with the "emugl-" prefix, and can be used to declare modules, what information they export to other modules, or import from them, and also what kind of auto-generated sources they depend on. Look at the comments inside common.mk and the Android.mk of the modules to better understand what's happening.