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USAGE.md

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Usage

There are many environnement variable to control gl4es behavour. All are numeric, except LIBGL_VERSION that take a string. 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.

LIBGL_FB

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
LIBGL_ES

Controls tje 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
LIBGL_GL

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
LIBGL_XREFRESH

Debug helper in specific cases

  • 0 : Default, nothing special
  • 1 : xrefresh will be called on cleanup
LIBGL_STACKTRACE

Automatic Backtrace log

  • 0 : Default, nothing special
  • 1 : stacktrace will be printed on crash
LIBGL_FPS

Print current FPS to the console

  • 0 : Defaut, don't mesure or printf FPS
  • 1 : Print FPS (on stdout) every second
LIBGL_VSYNC

VSync control

  • 0 : Default, nothing special
  • 1 : vsync enabled
LIBGL_RECYCLEFBO

Recycling FBO special case (don't delete a created FBO, but recycle it if needed)

  • 0 : Default, nothing special
  • 1 : Recycling of FBO enabled
LIBGL_MIPMAP

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
LIBGL_FORCENPOT

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.
LIBGL_TEXCOPY

Make a local copy of every texture for easy glGetTexImage2D

  • 0 : Default, nothing special
  • 1 : Texture copy enabled
LIBGL_SHRINK

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
LIBGL_TEXDUMP

Texture dump

  • 0 : Default, nothing special
  • 1 : Texture dump enabled
LIBGL_ALPHAHACK

Experimental: enable Alpha test only when using texture that contains an alpha channel

  • 0 : Default, nothing special
  • 1 : Alpha Hack enabled
LIBGL_NODOWNSAMPLING

Texture downsampling control (deprecated, use LIBGL_AVOID16BITS instead)

  • 0 : Default, DXTc texture are downsampled to 16bits
  • 1 : DXTc texture are left as 32bits RGBA
LIBGL_STREAM

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
LIBGL_COPY

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
LIBGL_NOLUMALPHA

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)
LIBGL_BLENDHACK

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)
LIBGL_BLENDCOLOR

Hack: Export a (faked) glBlendColor

  • 0 : Default, don't expose gBlendColor
  • 1 : Exposed the function (if no hadware support, faked function willbe used)
LIBGL_VERSION

Hack: Control the glGetString version. Overide version string (should be in the form of "1.x")

LIBGL_BATCH

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
LIBGL_NOERROR

Hack: glGetError() always return GL_NOERROR

  • 0 : Default, glGetError behave as it should
  • 1 : glGetError never fail.
LIBGL_GAMMA

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)
LIBGL_SRGB

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)
LIBGL_FASTMATH

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)
LIBGL_SILENTSTUB

Debug: Hide or Show the Sub / Not found message

  • 0 : Default, the messages are shown
  • 1 : Silent, don't print the STUB or glXGetProcAddress glXXXXX not found message
LIBGL_NOBANNER

Show/Hide initial text

  • 0 : Default, print starting message
  • 1 : Silent: no LIBGL message at start (combile with LIBGL_SILENTSTUB for more silence)
LIBGL_NPOT

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
LIBGL_GLQUERIES

Expose glQueries functions

  • 0 : Don't expose the function (fake one will be used if called)
  • 1 : Default, expose fake functions (always answer 0)
LIBGL_NOTEXMAT

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)
LIBGL_NOTEST

Initial Hardware test

  • 0 : Default, perform intial hardware testing (using a PBuffer)
  • 1 : Do not perform test (no extensions tested or used)
LIBGL_NOVAOCACHE

VAO Caching

  • 0 : Default, try to cache vao to avoid memcpy in render list
  • 1 : Don't cache VAO
LIBGL_VABGRA

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)
LIBGL_BEGINEND

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
LIBGL_AVOID16BITS

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)
LIBGL_AVOID24BITS

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 brake some blend functions (especialy on GLES 1.1 backend). Does not impact GL_UNSIGNED_SHORT_5_6_5 and friends.
LIBGL_POTFRAMEBUFFER

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)
LIBGL_NOBGRA

Ignore BGRA Texture hardware extension

  • 0 : Default, use BGRA extension if possible
  • 1 : Ignore BGRA extension, even if supported by GLES hardware
LIBGL_ES

Choose GLES hardware backend. WIP, don't use for now

  • 0 : Default, auto choose (GLES 1.1 for now on all platforms)
  • 1 : Use GLES 1.1 backend (so no shaders)
  • 2 : Use GLES 2.0 backend (shaders, but Fixed Pipeline function not implemented for now)
LIBGL_GL

Choose OpenGL version target for emulation

  • 0 : Default, auto choose (1.5 for now)
  • 15: Target OpenGL 1.5
  • 20: Target OpenGL 2.0 (with GLSL 1.10)
  • 21: Target OpenGL 2.1 (with GLSL 1.20)
LIBGL_NOHIGHP

Usage of highp precision in fragment shader (ES2 backend only)

  • 0 : Default, use highp if available
  • 1 : Disable usage of highp in Fragment shaders
LIBGL_COMMENTS

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
LIBGL_FBOMAKECURRENT

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)