Shader Writing and Integration

The mi_compute_irradiance shader interface function, if called to evaluate irradiance from final gathering, will return the average of all alphas from finalgather rays. It was previously undefined. This allows a simple form of ambient occlusion mapping.
A new geometry shader interface function mi_api_parameter_default allows supplying default values for declared numerical shader parameters.
The mi_X_from_Y shader interface functions now work when called from displacement shaders.
The [0] coordinate for hair was changed to a range of (0, 1) from the left to the right edge of the hair, as seen from the camera. Previously it was defined in the range (1, 0, 1) with 0 at the center.
Added a mi_trace_continue shader interface function that continues the current ray with the same state and type, as if the intersection had not happened.
Added a mi_api_touch geometry shader interface function to mark objects for re-evaluation.
In rasterizer (formerly called Rapid Motion) mode, environment shaders now receive the raster_x and raster_y state variables.
The miQ_GEO_LABEL mode of the mi_query shader interface function may now be used from displacement shaders.
Multiple finalgather file names can be attached to options with mi_api_taglist_reset.
The callback installed by the mi_disp_stream_cb_begin integration function receives a pointer to a tag list, not a single tag. This allows access to all frame buffers, not just the main color frame buffer. Also, the tags pointed to are the full frame buffers, not the small image rectangles, so it is necessary to use the xl and yl arguments to offset into them. (This will change again in 3.4.)
The 128-byte stub files now specify version number 3.3, and add another port number at the end that can be used for bidirectional connections that allow a realtime viewer to request arbitrary frame buffers, in their native format without interleaved 8-bit RGBA conversion. The imf_disp viewer does not support this new mode.
The second argument of the mi_lib_registry_lookup integration interface function now expects a miRL_* enum code instead of a miBoolean. The enum codes were chosen to be backwards compatible without recompilation.
The mi_raylib_init integration interface function now returns a boolean that indicates an initialization failure if miFALSE. Common reason for such a failure are failures to start threads, or a failure to create local loopback network connections because an overzealous Windows firewall prohibits it.
First derivatives on subdivision surface, free-form surface, and polygonal (if available) geometry are now made available to displacement shaders. Also, the result pointer passed to displacement shaders when displacing subdivision surfaces now points to cleared memory (this was already the case for other geometry types).
At startup, mental ray will record the thread priority and use it for all render threads it creates later. This allows the application that mental ray is embedded in to reduce rendering priority to keep the GUI responsive.
The .rayhosts file lists the names of slave hosts to attach to for network rendering. It is now possible to append -threads n to each line to control the number of threads on that host. This used to work in version 2.x but not 3.x.
Translators may specify triangle meshes as triangle lists, which directly correspond with renderable data structures without requiring tessellation. (The downside is that they change between major mental ray versions.)

home

<< prev

next >>

contents