Diff of /trunk/TODO

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	revision 1155, Sun May 8 14:43:30 2011 UTC	revision 1156, Sun May 8 21:20:52 2011 UTC
#	Line 1	Line 1
1	NOTE: GLK's approximate ranking of 5 most important tagged with	NOTE: GLK's approximate ranking of 5 most important tagged with
2	[GLK:1], [GLK:2], ...	[GLK:1], [GLK:2], ...
3
4	==============================	========================
5	other SHORT TERM =============  (including needed for LIC)	SHORT TERM ============= (*needed* for streamlines & tractography)
6	==============================	========================
	Add a clamp function, which takes three arguments; either three scalars:
	clamp(x, minval, maxval)  = max(minval, min(maxval, x))
	or three vectors of the same size:
	clamp([x,y], minvec, maxvec)  = [max(minvec[0], min(maxvec[0], x)),
	max(minvec[1], min(maxvec[1], y))]
	This would be useful in many current Diderot programs.
	One question: clamp(x, minval, maxval) is the argument order
	used in OpenCL and other places, but clamp(minval, maxval, x)
	would be more consistent with lerp(minout, maxout, x).
	Level of differentiability in field type should be statement about how
	much differentiation the program *needs*, rather than what the kernel
	*provides*.  The needed differentiability can be less than or equal to
	the provided differentiability.
7
8	[GLK:1] Add sequence types (needed for evals & evecs)	[GLK:1] Add sequence types (needed for evals & evecs)
9	syntax	syntax
10	types: ty '{' INT '}'	types: ty '{' INT '}'
11	value construction: '{' e1 ',' … ',' en '}'	value construction: '{' e1 ',' … ',' en '}'
12	indexing: e '{' e '}'	indexing: e '{' e '}'
13		[GLK:1] evals & evecs for symmetric tensor[3,3] (requires sequences)
14
15	IL support for higher-order tensor values (matrices, etc).	ability to emit/track/record variables into dynamically re-sized
16	tensor construction [DONE]	runtime buffer
	tensor indexing [DONE]
	tensor slicing
	verify that hessians work correctly [DONE]
	Use ∇⊗ etc. syntax
	syntax [DONE]
	typechecking
	IL and codegen
	test/uninit.diderot:
	documents need for better compiler error messages when output variables
	are not initialized; the current messages are very cryptic
17
18	determinant ("det") for tensor[3,3]	tensor fields: convolution on general tensor images
19
20	expand trace in mid to low translation	========================
21		SHORT-ISH TERM ========= (to make using Diderot less annoying/slow)
22		========================
23
24	value-numbering optimization	value-numbering optimization
25
26	Add type aliases for color types	proper handling of stabilize method
	rgb = real{3}
	rgba = real{4}
	==============================
	MEDIUM TERM ================== (including needed for streamlines & tractography)
	==============================
	[GLK:1] evals & evecs for symmetric tensor[3,3] (requires sequences)
27
28	[GLK:2] Save Diderot output to nrrd, instead of "mip.txt"	[GLK:2] Save Diderot output to nrrd, instead of "mip.txt"
29	For grid of strands, save to similarly-shaped array	For grid of strands, save to similarly-shaped array
#	Line 71	Line 39
39	*always* "inside"; with various ways of mapping the known image values	*always* "inside"; with various ways of mapping the known image values
40	to non-existant index locations.  One possible syntax emphasizes that	to non-existant index locations.  One possible syntax emphasizes that
41	there is a index mapping function that logically precedes convolution:	there is a index mapping function that logically precedes convolution:
42	F = bspln3 ⊛ (img ◦ clamp)	F = bspln3 ⊛ (img  clamp)
43	F = bspln3 ⊛ (img ◦ repeat)	F = bspln3 ⊛ (img ◦ repeat)
44	F = bspln3 ⊛ (img ◦ mirror)	F = bspln3 ⊛ (img ◦ mirror)
45	where "◦" or "∘" is used to indicate function composition	where "◦" or "∘" is used to indicate function composition
46
47	extend norm (|exp|) to all tensor types [DONE for vectors and matrices]	Use ∇⊗ etc. syntax
48		syntax [DONE]
49	ability to emit/track/record variables into dynamically re-sized	typechecking
50	runtime buffer	IL and codegen
	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.
51
52	[GLK:5] Want: non-trivial field expressions & functions:	Add a clamp function, which takes three arguments; either three scalars:
53	image(2)[2] Vimg = load(...);	clamp(x, minval, maxval)  = max(minval, min(maxval, x))
54	field#0(2)[] Vlen = |Vimg ⊛ bspln3|;	or three vectors of the same size:
55	to get a scalar field of vector length, or	clamp([x,y], minvec, maxvec)  = [max(minvec[0], min(maxvec[0], x)),
56	field#2(2)[] F = Fimg ⊛ bspln3;	max(minvec[1], min(maxvec[1], y))]
57	field#0(2)[] Gmag = |∇F|;	This would be useful in many current Diderot programs.
58	to get a scalar field of gradient magnitude, or	One question: clamp(x, minval, maxval) is the argument order
59	field#2(2)[] F = Fimg ⊛ bspln3;	used in OpenCL and other places, but clamp(minval, maxval, x)
60	field#0(2)[] Gmsq = ∇F•∇F;	would be more consistent with lerp(minout, maxout, x).
	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)
61
62	Want: ability to apply "normalize" to a field itself, e.g.	Level of differentiability in field type should be statement about how
63	field#0(2)[2] V = normalize(Vimg ⊛ ctmr);	much differentiation the program *needs*, rather than what the kernel
64	so that V(x) = normalize((Vimg ⊛ ctmr)(x)).	*provides*.  The needed differentiability can be less than or equal to
65	Having this would simplify expression of standard LIC method, and	the provided differentiability.
	would also help express other vector field expressions that arise
	in vector field feature exraction.
66
67	tensor fields: convolution on general tensor images	Add type aliases for color types
68		rgb = real{3}
69		rgba = real{4}
70
71	==============================	==============================
72	other MEDIUM TERM ============ (needed for particles)	MEDIUM TERM ================== (*needed* for particles)
73	==============================	==============================
74
	Put small 1-D and 2-D fields, when reconstructed specifically by tent
	and when differentiation is not needed, into faster texture buffers.
	test/illust-vr.diderot is good example of program that uses multiple
	such 1-D fields basically as lookup-table-based function evaluation
75	run-time birth of strands	run-time birth of strands
76
77	"initially" supports lists	"initially" supports lists
#	Line 124	Line 79
79	"initially" supports lists of positions output from	"initially" supports lists of positions output from
80	different initalization Diderot program	different initalization Diderot program
81
82	spatial data structure that permits strands' queries of neighbors	Communication between strands: they have to be able to learn each
83		other's state (at the previous iteration).  Early version of this can
84		have the network of neighbors be completely static (for running one
85		strand/pixel image computations).  Later version with strands moving
86		through the domain will require some spatial data structure to
87		optimize discovery of neighbors.
88
89		============================
90		MEDIUM-ISH TERM ============ (to make Diderot more useful/effective)
91		============================
92
93	proper handling of stabilize method	Python/ctypes interface to run-time
94
95	test/vr-kcomp2.diderot: Add support for code like	support for Python interop and GUI
96
97	(F1 if x else F2)@pos	Alow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,
98		provided that X*Y, X/Y, X+Y, X-Y are already supported.
99		Nearly every Diderot program would be simplified by this.
100
101	This will require duplication of the continuation of the conditional	Put small 1-D and 2-D fields, when reconstructed specifically by tent
102	(but we should only duplicate over the live-range of the result of the	and when differentiation is not needed, into faster texture buffers.
103	conditional.	test/illust-vr.diderot is good example of program that uses multiple
104		such 1-D fields basically as lookup-table-based function evaluation
105
106		expand trace in mid to low translation
107
108		extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
109
110		determinant ("det") for tensor[3,3]
111
112	add ":" for tensor dot product (contracts out two indices	add ":" for tensor dot product (contracts out two indices
113	instead of one like •), valid for all pairs of tensors with	instead of one like •), valid for all pairs of tensors with
114	at least two indices	at least two indices
115
116	==============================	test/uninit.diderot:
117	other MEDIUM TERM ============	documents need for better compiler error messages when output variables
118	==============================	are not initialized; the current messages are very cryptic
119
120	want: warnings when "D" (reserved for differentiation) is declared as	want: warnings when "D" (reserved for differentiation) is declared as
121	a variable name (get confusing error messages now)	a variable name (get confusing error messages now)
122
123	support for Python interop and GUI	==============================
124		LONG TERM ==================== (make Diderot more interesting/attractive from
125		==============================  a research standpoint)
126
127	Python/ctypes interface to run-time	IL support for higher-order tensor values (matrices, etc).
128		tensor construction [DONE]
129		tensor indexing [DONE]
130		tensor slicing
131		verify that hessians work correctly [DONE]
132
133		Better handling of variables that determines the scope of a variable
134		based on its actual use, instead of where the user defined it.  So,
135		for example, we should lift strand-invariant variables to global
136		scope.  Also prune out useless variables, which should include field
137		variables after the translation to mid-il.
138
139		test/vr-kcomp2.diderot: Add support for code like
140		(F1 if x else F2)@pos
141		This will require duplication of the continuation of the conditional
142		(but we should only duplicate over the live-range of the result of the
143		conditional.
144
145		[GLK:5] Want: non-trivial field expressions & functions:
146		image(2)[2] Vimg = load(...);
147		field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
148		to get a scalar field of vector length, or
149		field#2(2)[] F = Fimg ⊛ bspln3;
150		field#0(2)[] Gmag = |∇F|;
151		to get a scalar field of gradient magnitude, or
152		field#2(2)[] F = Fimg ⊛ bspln3;
153		field#0(2)[] Gmsq = ∇F•∇F;
154		to get a scalar field of squared gradient magnitude, which is simpler
155		to differentiate.  However, there is value in having these, even if
156		the differentiation of them is not supported (hence the indication
157		of "field#0" for these above)
158
159		Want: ability to apply "normalize" to a field itself, e.g.
160		field#0(2)[2] V = normalize(Vimg ⊛ ctmr);
161		so that V(x) = normalize((Vimg ⊛ ctmr)(x)).
162		Having this would simplify expression of standard LIC method, and
163		would also help express other vector field expressions that arise
164		in vector field feature exraction.
165
166		Permit fields composition, especially for warping images by a
167		smooth field of deformation vectors
168		field#2(3)[3] warp = bspln3 ⊛ warpData;
169		field#2(3)[] F = bspln3 ⊛ img;
170		field#2(3)[] Fwarp = F ◦ warp;
171		So Fwarp(x) = F(warp(X)).  Chain rule can be used for differentation
172
173	Allow the convolution to be specified either as a single 1D kernel	Allow the convolution to be specified either as a single 1D kernel
174	(as we have it now):	(as we have it now):
#	Line 162	Line 181
181	we should notate the gradient, when we only want to differentiate with	we should notate the gradient, when we only want to differentiate with
182	respect to some of the axes.	respect to some of the axes.
183
	==============================
	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.
184	co- vs contra- index distinction	co- vs contra- index distinction
185
186	some indication of tensor symmetry	some indication of tensor symmetry

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