NOTE: GLK's approximate ranking of 5 most imporant tagged with
[GLK:1], [GLK:2], ...
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SHORT TERM ============= (for curvature-based VR)
========================
IL support for higher-order tensor values (matrices, etc).
tensor construction [DONE]
tensor indexing [DONE]
tensor slicing
verify that hessians work correctly [DONE]
Use ∇⊗ etc. syntax
syntax [DONE]
typechecking
IL and codegen
Add sequence types
syntax
types: ty '{' INT '}'
value construction: '{' e1 ',' … ',' en '}'
indexing: e '{' e '}'
==============================
other SHORT TERM ============= (including needed for LIC)
==============================
test/uninit.diderot:
documents need for better compiler error messages when output variables
are not initialized; the current messages are very cryptic
determinant ("det") for tensor[3,3]
extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
expand trace in mid to low translation
value-numbering optimization
Add type aliases for color types
rgb = real{3}
rgba = real{4}
==============================
MEDIUM TERM ================== (including needed for streamlines & tractography)
==============================
[GLK:2] evals & evecs for symmetric tensor[3,3] (requires sequences)
[GLK:3] Save Diderot output to nrrd, instead of "mip.txt"
For grid of strands, save to similarly-shaped array
For list of strands, save to long 1-D (or 2-D for non-scalar output) list
For ragged things (like tractography output), will need to save both
complete list of values, as well as list of start indices and lengths
to index into complete list
[GLK:4] Use of Teem's "hest" command-line parser for getting
any input variables that are not defined in the source file
[GLK:5] ability to declare a field in such a way so that probe
positions are *always* clamped to the support of "inside";
there are many cases where this is the sensible behavior.
(More generally, we could also have "repeat" declaration,
copying action of GL_REPEAT in texturing)
ability to emit/track/record variables into dynamically re-sized
runtime buffer
Want: allow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,
provided that X*Y, X/Y, X+Y, X-Y are already supported.
Nearly every Diderot program would be simplified by this.
Want: non-trivial field expressions & functions:
image(2)[2] Vimg = load(...);
field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
to get a scalar field of vector length, or
field#2(2)[] F = Fimg ⊛ bspln3;
field#0(2)[] Gmag = |∇F|;
to get a scalar field of gradient magnitude, or
field#2(2)[] F = Fimg ⊛ bspln3;
field#0(2)[] Gmsq = ∇F•∇F;
to get a scalar field of squared gradient magnitude, which is simpler
to differentiate. However, there is value in having these, even if
the differentiation of them is not supported (hence the indication
of "field#0" for these above)
Want: ability to apply "normalize" to a field itself, e.g.
field#0(2)[2] V = normalize(Vimg ⊛ ctmr);
so that V(x) = normalize((Vimg ⊛ ctmr)(x)).
Having this would simplify expression of standard LIC method, and
would also help express other vector field expressions that arise
in vector field feature exraction.
tensor fields: convolution on general tensor images
==============================
other MEDIUM TERM ============ (needed for particles)
==============================
run-time birth and death of strands
"initially" supports lists
"initially" supports lists of positions output from
different initalization Diderot program
spatial data structure that permits strands' queries of neighbors
proper handling of stabilize method
test/vr-kcomp2.diderot: Add support for code like
(F1 if x else F2)@pos
This will require duplication of the continuation of the conditional
(but we should only duplicate over the live-range of the result of the
conditional.
==============================
other MEDIUM TERM ============
==============================
want: warnings when "D" (reserved for differentiation) is declared as
a variable name (get confusing error messages now)
support for Python interop and GUI
==============================
LONG TERM ====================
==============================
Better handling of variables that determines the scope of a variable
based on its actual use, instead of where the user defined it. So,
for example, we should lift strand-invariant variables to global
scope. Also prune out useless variables, which should include field
variables after the translation to mid-il.
co- vs contra- index distinction
add ":" for tensor dot product (contracts out two indices
instead of one like •), valid for all pairs of tensors with
at least two indices
some indication of tensor symmetry
(have to identify the group of index permutations that are symmetries)
dot works on all tensors
outer works on all tensors
Einstein summation notation
"tensor comprehension" (like list comprehension)
Python/ctypes interface to run-time
======================
BUGS =================
======================
[GLK:1] test/fields.diderot:
documents various bugs/questions associated with simple field expressions
(negation, addition, scalar multiplication)
test/read2vecs.diderot:
// HEY (BUG?) shouldn't it be a type error to load this 2-D array of
// 2-vectors into a 2-D *scalar* field? Instead, get:
// uncaught exception Fail [Fail: Error in compiling lic.diderot]
// raised at driver/main.sml:31.39-31.76
image(2)[] Vimg = load("../data/vorttest.nrrd");
test/vr-kcomp.diderot:
// HEY (scoping BUG): the strand parameters (e.g. ui, vi) ...
test/zslice2.diderot:
// HEY (bug) bspln5 leads to problems ...
// uncaught exception Size [size]
// raised at c-target/c-target.sml:47.15-47.19
//field#4(3)[] F = img ⊛ bspln5;