Diff of /branches/pure-cfg/TODO

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	revision 961, Sat Apr 23 19:32:22 2011 UTC	revision 962, Sat Apr 23 19:33:19 2011 UTC
#	Line 1	Line 1
1
2		NOTE: GLK's approximate ranking of 6 most imporant tagged with
3		[GLK:1], [GLK:2], ...
4
5	========================	========================
6	SHORT TERM =============  (for curvature-based VR)	SHORT TERM =============  (for curvature-based VR)
7	========================	========================
#	Line 65	Line 69
69	MEDIUM TERM ================== (including needed for streamlines & tractography)	MEDIUM TERM ================== (including needed for streamlines & tractography)
70	==============================	==============================
71
72		[GLK:3] evals & evecs for symmetric tensor[3,3] (requires sequences)
73
74		[GLK:4] Save Diderot output to nrrd, instead of "mip.txt"
75		For grid of strands, save to similarly-shaped array
76		For list of strands, save to long 1-D (or 2-D for non-scalar output) list
77		For ragged things (like tractography output), will need to save both
78		complete list of values, as well as list of start indices and lengths
79		to index into complete list
80
81		[GLK:5] Use of Teem's "hest" command-line parser for getting
82		any input variables that are not defined in the source file
83
84		[GLK:6] ability to declare a field in such a way so that probe
85		positions are *always* clamped to the support of "inside";
86		there are many cases where this is the sensible behavior.
87		(More generally, we could also have "repeat" declaration,
88		copying action of GL_REPEAT in texturing)
89
90		ability to emit/track/record variables into dynamically re-sized
91		runtime buffer
92
93	Want: allow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,	Want: allow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,
94	provided that X*Y, X/Y, X+Y, X-Y are already supported.	provided that X*Y, X/Y, X+Y, X-Y are already supported.
95	Nearly every Diderot program would be simplified by this.	Nearly every Diderot program would be simplified by this.
96
97	Want: ability to apply "normalize" to a field itself, e.g.	Want: non-trivial field expressions & functions:
	field#1(2)[2] V = normalize(Vimg ⊛ ctmr);
	so that V(x) = normalize((Vimg ⊛ ctmr)(x)).
	(For now, it would be okay for the differentability of V to be 0;
	later we can teach Diderot the quotient rule of derivatives.)
	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
	Related to this and possibly simpler:
98	image(2)[2] Vimg = load(...);	image(2)[2] Vimg = load(...);
99	field#0(2)[] Vlen = |Vimg ⊛ bspln3|;	field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
100	to get a scalar field of vector length, or	to get a scalar field of vector length, or
#	Line 87	Line 104
104	field#2(2)[] F = Fimg ⊛ bspln3;	field#2(2)[] F = Fimg ⊛ bspln3;
105	field#0(2)[] Gmsq = ∇F•∇F;	field#0(2)[] Gmsq = ∇F•∇F;
106	to get a scalar field of squared gradient magnitude, which is simpler	to get a scalar field of squared gradient magnitude, which is simpler
107	to differentiate.  Again, though, it would be such a benefit to have	to differentiate.  However, there is value in having these, even if
108	these expressions, without any differentiability.  Hence my indication	the differentiation of them is not supported (hence the indication
109	of "field#0" for these above.	of "field#0" for these above)
	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
110
111	ability to emit/track/record variables into dynamically re-sized	Want: ability to apply "normalize" to a field itself, e.g.
112	runtime buffer	field#0(2)[2] V = normalize(Vimg ⊛ ctmr);
113		so that V(x) = normalize((Vimg ⊛ ctmr)(x)).
114	evals & evecs for symmetric tensor[3,3]	Having this would simplify expression of standard LIC method, and
115		would also help express other vector field expressions that arise
116		in vector field feature exraction.
117
118	tensor fields: convolution on general tensor images	tensor fields: convolution on general tensor images
119
	Use of Teem's "hest" command-line parser for getting
	any input variables that are not defined in the source file
	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
120	==============================	==============================
121	other MEDIUM TERM ============ (needed for particles)	other MEDIUM TERM ============ (needed for particles)
122	==============================	==============================
#	Line 131	Line 136
136
137	(F1 if x else F2)@pos	(F1 if x else F2)@pos
138
139	This will require duplication of the continuation of the conditional (but we should only	This will require duplication of the continuation of the conditional
140	duplicate over the live-range of the result of the conditional.	(but we should only duplicate over the live-range of the result of the
141		conditional.
142
143	==============================	==============================
144	other MEDIUM TERM ============	other MEDIUM TERM ============
#	Line 176	Line 182
182	BUGS =================	BUGS =================
183	======================	======================
184
185	test/fields.diderot:	[GLK:1] test/derivs2.diderot:
186	documents various bugs/questions associated with field expressions	test/derivs3.diderot:
187		gradients & Hessians are not being transformed from index-to-world,
188		these test programs should produce black images when that is working
189
190		[GLK:2] test/fields.diderot:
191		documents various bugs/questions associated with simple field expressions
192		(negation, addition, scalar multiplication)
193
194		test/read2vecs.diderot:
195		// HEY (BUG?) shouldn't it be a type error to load this 2-D array of
196		// 2-vectors into a 2-D *scalar* field?  Instead, get:
197		//   uncaught exception Fail [Fail: Error in compiling lic.diderot]
198		//     raised at driver/main.sml:31.39-31.76
199		image(2)[] Vimg = load("../data/vorttest.nrrd");
200
201		test/iso2d.diderot: not able to use "nan".
202		// HEY (BUG) not able to use NaN as in "pos = [nan,nan]"
203		// generated C code "vec2f(nanf, nanf)" causes problems:
204		// iso2d.c: In function ‘sample_update’:
205		// iso2d.c:86: error: incompatible type for argument 1 of ‘vec2f’
206		// iso2d.c:86: error: incompatible type for argument 2 of ‘vec2f’
207		// uncaught exception Fail [Fail: error compiling/linking]
208		//   raised at c-target/c-target.sml:323.14-323.44
209		pos = [∞,∞];  // should be: pos = [nan,nan];
210
211	test/mip-cam.diderot:	test/mip-cam.diderot:
212	// generated C code looks like "(float)p_ui_0--0.5e0f"	// generated C code looks like "(float)p_ui_0--0.5e0f"

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