add more docs in readme - probably a good idea since these magic env
vars are very useful at times SVN revision: 51771
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@ -189,6 +189,97 @@ more. it also supports opengl-es2.0 and is reliant on modern opengl2.0+
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shader support. this engine also supports the native surface api for
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adopting pixmaps directly to textures for compositing.
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some environment variables that control the opengl engine are as
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follows:
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export EVAS_GL_INFO=1
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set this environment variable to enable output of opengl information
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such as vendor, version, extensions, maximum texture size etc. unset
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the environment variable to make the output quiet again.
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export EVAS_GL_MEMINFO=1
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set this environment variable to enable dumping of debug output
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whenever textures are allocated or freed, giving the number of
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textures of each time and how many kb worth of pixel data are
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allocated for the textures. unset it again to stop this dumping of
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information.
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export EVAS_GL_WIN_RESURF=1
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set this environment variable to enable the gl engine to try and
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ddelete the window surface, if it can, when told to "dump resources"
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to save memory, and re-allocate it when needed (when rendering
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occurs). unset it to not have this behavior.
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export EVAS_GL_CUTOUT_MAX=N
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set this environment variable to the maximum number of rectangles
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applied to a rendering of a primitive that "cut away" parts of that
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primitive to render to avoid overdraw. default is 512. unset it to use
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defaults, otherwise set N to the max value desired or to -1 for
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"unlimited rectangles".
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export EVAS_GL_PIPES_MAX=N
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set the maximum number of parallel pending pipelines to N. the
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default number is 32 (except on tegra2 where is it 1). evas keeps 1 (or more)
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pipelines of gl draw commands in parallel at any time, to allow for merging
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of non-overlapping draw commands to avoid texture binding and context
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changes which allows for more streamlining of the draw arrays that are
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filled and passed to gl per frame. the more pipelines exist, the more
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chance evas has of merging draw commands that have the same modes,
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texture source etc., but the more overhead there is in finding a
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pipeline slot for the draw command to merge into, so there is a
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compromise here between spare cpu resources and gpu pipelining. unset
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this environment variable to let evas use it's default value.
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export EVAS_GL_ATLAS_ALLOC_SIZE=N
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set the size (width in pixels) of the evas texture atlas strips that
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are allocated. the default is 1024. unset this to let evas use its
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default. if this value is larger than the maximum texture size, then it
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is limited to that maximum size internally anyway. evas tries to
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store images together in "atlases". these are large single textures
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that contain multiple images within the same texture. to do this evas
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allocates a "wide strip" of pixels (that is a certain height) and then
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tries to fit all images loaded that need textures into an existing
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atlas texture before allocating a new one. evas tries a best fit
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policy to avoid too much wasting of texture memory. texture atlas
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textures are always allocated to be EVAS_GL_ATLAS_ALLOC_SIZE width,
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and a multiple of EVAS_GL_ATLAS_SLOT_SIZE pixels high (if possible -
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power of 2 limits are enforced if required).
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export EVAS_GL_ATLAS_ALLOC_ALPHA_SIZE=N
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this is exactly the same as EVAS_GL_ATLAS_ALLOC_SIZE, but for
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"alpha" textures (texture used for font glyph data). it works exactly
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the same way as for images, but per font glyph being put in an atlas
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slot. the default value for this is 4096.
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export EVAS_GL_ATLAS_MAX_W=N
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set this to limit the maximum image size (width) that will be
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allowed to go into a texture atlas. if an image exceeds this size, it
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gets allocated its own separate individual texture (this is to help
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minimize fragmentation). the default value for this is 512. if you set
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this environment variable it will be overridden by the value it is set
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to. the maximum value possible here is 512. you may set it to a
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smaller value.
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export EVAS_GL_ATLAS_MAX_H=N
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this is the same as EVAS_GL_ATLAS_MAX_W, but sets the maximum height
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of an image that is allowed into an atlas texture.
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export EVAS_GL_ATLAS_SLOT_SIZE=N
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this sets the height granularity for atlas strips. the default (and
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minimum) value is 16. this means texture atlas strips are always a
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multiple of 16 pixels high (16, 32, 48, 64, etc...). this allows you
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to change the granularity to another value to avoid having more
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textures allocated or try and consolidate allocations into fewer atlas
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strips etc.
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export EVAS_GL_NO_MAP_IMAGE_SEC=1
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if this environment variable is set, it disabled support for the SEC
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map image extension (a zero copy direct-texture access extension that
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removes texture upload overhead). if you have problems with dynamic
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evas images, and this is detected by evas (see EVAS_GL_INFO above to
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find out if its detected), then setting this will allow it to be
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forcibly disabled. unset it to allow auto-detection to keep working.
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--enable-gl-flavor-gles
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this enables the opengl-es 2.0 flavor of opengl (as opposed to desktop
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@ -293,13 +384,13 @@ actually can beat the c code (when compiled with all optimizations) in speed.
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--enable-cpu-neon
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This enables support for the Arm Cortex-A8 and later Neon register
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set. In particular it will use neon optimised code for rotations and
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set. In particular it will use neon optimized code for rotations and
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drawing with the software engines. Open GL based renderers will gain
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nothing from the use of neon.
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To use neon with gcc-4.4 you need a post-2009 gcc and options
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something like: -mcpu=cortex-a8 -mfloat-abi=softfp -mfpu=neon
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Note that this slightly slows down non-optimised parts of evas but
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Note that this slightly slows down non-optimized parts of evas but
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the gains in drawing are more then worth it overall.
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This is enabled by default, and turns off if a small test program is
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@ -573,7 +664,7 @@ This has been tested on x86 desktop and laptop cpu's with 2 and 4
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cores and it works well, but there seem to be some issues on tested
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multi-core ARM platforms like the nvidia tegra2. The source of issue is
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unknown but you will notice rendering bugs with missing content or
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incorectly drawn content. This requires you also set the environment
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incorrectly drawn content. This requires you also set the environment
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variable EVAS_RENDER_MODE to "non-blocking" to enable it at runtime,
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as the compile-time enable simply sets up the feature to be ready to
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work. The runtime switch actually turns it on. If you don't plan to
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