There are many environnement variable to control gl4es behavour. All are numeric, except LIBGL_VERSION that take a string, LIBGL_FBO that takes a 2d size (WxH), and both LIBGL_EGL and LIBGL_GLES that take path/filename.
You can also change many of this variable at runtime using the glHint(...) function. See gl4eshint.h for the list of #define to use in this function.
Controls the Framebuffer output
- 0 : Default, using standard x11 rendering
- 1 : Use Framebuffer output (x11 bypassed, only fullscreen)
- 2 : Use Framebuffer, but also an intermediary FBO
- 3 : Use PBuffer, allowing x11 (and windowed) rendering even if driver doesn't support it
Controls the version of GLES to use
- 0 : Default, using GLES 1.1 backend (unless built with DEFAULT_ES 2)
- 1 : Use GLES 1.1 backend
- 2 : Use GLES 2.0 backend
Controls the version of OpenGL exposed
- 0 : Default, expose OpenGL 1.5 when using GLES1.1 or OpenGL 2.0 when using GLES2.0
- 15: Expose OpenGL 1.5
- 20: Expose OpenGL 2.0
- 21: Expose OpenGL 2.1
Debug helper in specific cases
- 0 : Default, nothing special
- 1 : xrefresh will be called on cleanup
Automatic Backtrace log
- 0 : Default, nothing special
- 1 : stacktrace will be printed on crash
Print current FPS to the console
- 0 : Defaut, don't mesure or printf FPS
- 1 : Print FPS (on stdout) every second
VSync control
- 0 : Default, nothing special
- 1 : vsync enabled
Recycling FBO special case (don't delete a created FBO, but recycle it if needed)
- 0 : Default, nothing special
- 1 : Recycling of FBO enabled
Handling of Manual and Automatic MIPMAP
- 0 : Default, nothing special
- 1 : AutoMipMap forced
- 2 : guess AutoMipMap (based on manual mipmaping on textures)
- 3 : ignore MipMap (mipmap creation / use entirely disabled)
- 4 : ignore AutoMipMap on non-squared textures
- 5 : calculate all sub-mipmap one time when uploading level 1
Forcing NPOT (Non-Power of Two) Texture size.
- 0 : Default, nothing special
- 1 : If hardware only support Limited NPOT, then disabling MIPMAP (i.e. LIBGL_MIPMAP=3), so all texture can be NPOT. If Hardware support full NPOT, do nothing special. Usefull for GLES2 backend where limited NPOT is always supported.
Make a local copy of every texture for easy glGetTexImage2D
- 0 : Default, nothing special
- 1 : Texture copy enabled
Texture shrinking control
- 0 : Default, nothing special
- 1 : everything / 2 (using original algorithm for size reduction, all other shink mode use a refined algorithm)
- 2 : only textures wich one size > 512 are / 2
- 3 : only textures wich one size > 256 are / 2
- 4 : only textures wich one size > 256 are / 2, and the one > 1024 are / 4
- 5 : only textures wich one size > 256 are resized to 256 (if possible, because only /2 and /4 exists), but empty texture are not shrinked
- 6 : only textures wich one size > 128 are / 2, thoses >= 512 are resized to 256 (if possible, because only /2 and /4 exists), but empty texture are not shrinked
- 7 : only textures wich one size > 512 are / 2, but empty texture are not shrinked
- 8 : advertise a max texture size *4, but every texture wich one size > 2048 are shrinked to 2048
- 9 : advertise a max texture size *4, but every texture wich one size > 4096 are / 4 and the one > 512 are / 2, but empty texture are not shrinked
- 10: advertise a max texture size *4, but every texture wich one size > 2048 are / 4 and the one > 512 are / 2, but empty texture are not shrinked
- 11: advertise a max texture size *2, but every texture with one dimension > max texture size will get shrinked to max texture size
Texture dump
- 0 : Default, nothing special
- 1 : Texture dump enabled
Experimental: enable Alpha test only when using texture that contains an alpha channel
- 0 : Default, nothing special
- 1 : Alpha Hack enabled
Texture downsampling control (deprecated, use LIBGL_AVOID16BITS instead)
- 0 : Default, DXTc texture are downsampled to 16bits
- 1 : DXTc texture are left as 32bits RGBA
PANDORA only: enable Texture Streaming (works only on RGB textures)
- 0 : Default, nothing special
- 1 : Enabled on empty RGB textures
- 2 : Enabled on all RGB textures
Control the glCopyTex(Sub)Image2D hack (they are buggy on pandora and don't work most of the time)
- 0 : Don't use native glCopyTex(Sub)Image2D, but a workaround function using FBO
- 1 : No glCopyTexImage2D / glCopyTexSubImage2D hack, use native ones
Control the availability of the LUMUNANCE_ALPHA format (can be buggy on Pandora model CC)
- 0 : Default,GL_LUMINANCE_ALPHA is available and used if needed
- 1 : GL_LUMINANCE_ALPHA hardware support disabled (a GL_RGBA texture will be used instead)
Experimental: Change Blend GL_SRC_ALPHA, GL_ONE to GL_ONE, GL_ONE
- 0 : Default, nothing special
- 1 : Change Blend GL_SRC_ALPHA, GL_ONE to GL_ONE, GL_ONE (can be usefull for Xash3D engine)
Hack: Export a (faked) glBlendColor
- 0 : Default, don't expose gBlendColor
- 1 : Exposed the function (if no hadware support, faked function willbe used)
Hack: Control the glGetString version. Overide version string (should be in the form of "1.x")
This has been changed with v1.0.5. Now BATCH simply try to merge subsequents glDrawXXXXX (glDrawArrays, glDrawElements...). It only try to merge if arrays is less the 10N vertices The Batching stop when there is a change of GL State, but also if an Array of more then 100N is encountered.
- 0 : Default: don't try to merge glDrawXXXXX
- N : Any number: try to merger arrays, 1st must be less than 10N, max is 100N vertices
Hack: glGetError() always return GL_NOERROR
- 0 : Default, glGetError behave as it should
- 1 : glGetError never fail.
Pandora Hack: Set a Gamma value (in decimal formal, 1.0 means no gamma boost)
- X.Y : Use X.Y as gamma when creating context (typical value can be 1.6 or 2.0)
ODROID Hack: Enable sRGB Surface (so Gamma corrected), if Hardware support it
- 0 : Default, don't try to use sRGB surface
- 1 : Enable sRGB Surface (but support will be tested first, must have EGL_KHR_gl_colorspace extension)
Hack: Activate some Fast Math in processor/coprocessor
- 0 : Default, nothing special
- 1 : On OpenPandora and CHIP, activate "RunFast" on Cortex-A8 (mode default NaN, flush-to-zero) : Not implemented on other platforms (will do nothing)
Debug: Hide or Show the Sub / Not found message
- 0 : The messages for Stub or absend function are printed
- 1 : Default, don't print the STUB or glXGetProcAddress glXXXXX not found message
Show/Hide initial text
- 0 : Default, print starting message
- 1 : Silent: no LIBGL message at start (combine with LIBGL_SILENTSTUB for more silence)
Expose NPOT (Non Power of Two) Support
- 0 : Default, expose the extension that are availble by the GLES backend
- 1 : Expose limited NPOT extension
- 2 : Expose GL_ARB_texture_non_power_of_two extension
Expose glQueries functions
- 0 : Don't expose the function (fake one will be used if called)
- 1 : Default, expose fake functions (always answer 0)
Handling of Texture Matrix
- 0 : Default, perform handling internaly (better handling of NPOT texture on all hardware)
- 1 : Let the driver handle texmat (can be faster in some cases, but NPOT texture may be broken)
Initial Hardware test
- 0 : Default, perform intial hardware testing (using a PBuffer)
- 1 : Do not perform test (no extensions tested or used)
VAO Caching
- 0 : Default, try to cache vao to avoid memcpy in render list
- 1 : Don't cache VAO
Vertex Array BGRA extension
- 0 : Default, GL_ARB_vertex_array_bgra not exposed (still emulated)
- 1 : Extension exposed may be faster in some cases (Arx Libertatis mainly)
Merge of subsequent glBegin/glEnd blocks (will be non-effective if BATCH mode is used)
- 0 : Don't try to merge
- 1 : Try to merge, even if there is a glColor / glNormal in between (default)
- 2 : Try hard to merge, even if there is a glColor / glNormal or Matrix operations in between
Try to avoid 16bits textures
- 0 : Default, use 16bits texture if it can avoid a convertion or for DXTc textures
- 1 : Use 32bits texture unless specifically requested (using internalformat)
Try to avoid 24bits textures (i.e. GL_RGB)
- 0 : Default, use 24bits texture when it's possible
- 1 : Force 32bits textures when GL_RGB is asked (as internal or not). Not recommanded, as it may break some blend functions (especialy on GLES 1.1 backend). Does not impact 16bits formats.
Try to use 16bits textures
- 0 : Default, don't force 16bits texture
- 1 : Use 16bits texture instead of 32bits (i.e. use RGBA4 instead of RGBA8 and RGB5 instead of RGB8)
Use only Power Of Two dimension for Framebuffer
- 0 : Default, use NPOT dimension if supported
- 1 : Force Framebuffer to be created with POT dimension (not advised on GLES2 backend)
Ignore BGRA Texture hardware extension
- 0 : Default, use BGRA extension if possible
- 1 : Ignore BGRA extension, even if supported by GLES hardware
Usage of highp precision in fragment shader (ES2 backend only)
- 0 : Default, use highp if available
- 1 : Disable usage of highp in Fragment shaders
Comments in shaders are kept (also for generated shaders by fpe_shaders)
- 0 : Default, no comments in shaders sent to GLES Hardware
- 1 : Comments are left in Shaders sent to GLES Hardware
Hack to define default WRAP mode for texture
- 0 : Default wrap mode is GL_REPEAT (normal OpenGL behavour): default on NPOT hardware
- 1 : Default wrap mode is GL_CLAMP_TO_EDGE: default on limited NPOT or non-NPOT hardware
- 2 : Default wrap mode is GL_CLAMP_TO_EDGE, enforced (not advised)
Workaround for FBO and glXMakeCurrent (force unbind/bind FBO when changing context)
- 0 : Disabled (Default on mast configuration)
- 1 : Enabled (Default if Vendor is ARM or if using LIBGL_FB 1 and 2)
For the Color Attachment 0 to be a Texture2D (even if program attachs a Renderbuffer) => may speedup glBlitFramebuffer if used
- 0 : Default, don't force
- 1 : For Color Attachment 0 of FBO to be a texture
PANDORA and CHIP only: define custom dimension for FBO (only used with LIBGL_FBO=2)
- WxH : Define FBO of WxH size (ex: LIBGL_FBO=1280x720)
Hack to force using discrete Texture instead of Array in all shader
- 0 : Default: Array of texture is used in shaders (not in FPE generated ones)
- 1 : Individual texture are forced in shaders (shaders may fail to compile if array are accessed by indice)
Log to the console Shader Compile error, with initial and ShaderConv'd source of the shader
- 0 : Default, don't log
- 1 : Log Shader Compilation Errors
Disable the use of Depth texture
- 0 : Default, Use Depth Texture if supported by Hardware
- 1 : Disable the use of Depth Texture (renderbuffer will be used in FBO)
Define EGL lib to use. Default folder are the standard one for dynamic librarie loading (LD_LIBRARY_PATH and friend) plus "/opt/vc/lib/", /usr/local/lib/" and "/usr/lib/".
- by default try to use libbrcmEGL and libEGL
- filename: try to load from the defaults folder (don't forget to use complete filename, with ".so" extension). If not found/loaded, default one will be tried.
- /path/to/filename: try to use exact path/filename. If not found/loaded, default one will be tried.
Define GLES(2) lib to use. Default folder are the standard one for dynamic librarie loading (LD_LIBRARY_PATH and friend) plus "/opt/vc/lib/", /usr/local/lib/" and "/usr/lib/". Be sure to point to correct GLES library depanding on wich GLES backend you are using.
- by default try to use libGLESv1_CM, libGLES_CM or libbrcmGLESv1_CM for GLES1.1 and libGLESv2_CM, libGLESv2 or libbrcmGLESv2 for GLES2 backend
- filename: try to load from the defaults folder (don't forget to use complete filename, with ".so" extension). If not found/loaded, default one will be tried.
- /path/to/filename: try to use exact path/filename. If not found/loaded, default one will be tried.