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My polygon mesh generating/processing/morphing library using core.matrix is shaping up nicely: https://github.com/pkobrien/cad/tree/master/src/cad/mesh
Right now I'm not scaling my seed platonic solids properly. Basic stuff. I'm reading up on 3D graphics algorithms so I actually know what I'm doing at a lower level.
And I ran into an old issue with -0.0 in my normals but haven't been able to recreate it yet this morning.
Anyhow, I should have these issues resolved today. Then I will start looking at performance more.
Right now one of my main bottlenecks is in writing to the X3D xml files. I'm going to have to create a custom writer to make it lazier because I've maxed out all the tricks I can play with making things lazy using clojure.data.xml
Okay, scaling has been properly implemented and the platonic solid construction looks pretty good now.
This is how I'm calculating a face normal now:
(defn normal "Returns the ortho normal of the first three points passed in." ([[a b c]] (normal a b c)) ([a b c] (mx/normalise! (mx/cross (mx/sub b a) (mx/sub c a)))))
The problem is that this can create a Vector3 having an x, y, or z component with a value of -0.0 and Clojure has a bug related to that which messes up some other functions of mine.
So my fix in my old code was to do this:
(defn normal "Returns the ortho normal of the first three points passed in." ([[a b c]] (normal a b c)) ;([a b] (gc/normalize (gc/cross a b))) ([a b c] (apply point (mapv (comp mu/round2safe mu/abs-zero) (mx/normalise (mx/cross (- b a) (- c a)))))))
@mikera: Now that I'm using core.matrix what's the best way to apply
abs-zero to a
Vector3 as part of my
(def ZERO-VECTOR3 (Vector3/of 0.0 0.0 0.0)) (defn abs-zero [^Vector3 v] (if (.isZero v) ZERO-VECTOR3 v))
i.e. replace with a constant zero Vector3 whenever required. Avoids unnecessary new allocations.
That costs you one extra protocol dispatch.... so not too much but might be painful in an inner loop
@mikera: We're not quite on the same page. I only need to replace one component of the Vector3 if it is -0.0. The other components might be okay. So, for example [1.0 -0.0 5.25]
It is about 5x faster than a Clojure mapv on my machine, even with small vectors like this
About to do a new release of vectorz-clj.... any issues discovered that you'd like a fix for?
No, all the problems I'm having are my own doing. Haven't found any problems with core.matrix so far.
that fix works like a charm:
(mx/emap mu/abs-zero (mx/normalise! (mx/cross (mx/sub b a) (mx/sub c a))))
oh, I can make that
(mx/emap! mu/abs-zero (mx/normalise! (mx/cross (mx/sub b a) (mx/sub c a)))) can't I?
@mikera: I'm getting this error:
CompilerException java.lang.ClassCastException: mikera.vectorz.Vector3 cannot be cast to java.lang.Number,
when I try to do this:
opposite-face (fn [outer-face thickness] (vec (for [vert (reverse outer-face)] (+ vert (* (vert-normal-map vert) (- thickness))))))
ah, this is failing:
(defn normal "Returns the normal for the vertex as the average of the face normals." [mesh vert] (let [face-normal-map (mp/face-normal-map mesh) vert-faces-map (mp/vert-faces-map mesh) xf (comp (map face-normal-map) (distinct)) vnorm (fn [vert] (->> (vert-faces-map vert) (transduce xf + (mc/point 0 0 0)) (mx/normalise!)))] (vnorm vert)))
Are your + and * the core.matrix operators or the clojure ones? That's the error I'd expect if you try and pass a vector to a clojure numerical operator
Also worth checking the types of values are correct at each stage of your operations. I recommend unit tests to do that, especially for the results of functions like face-normal-map
I have no unit tests yet - this has been a WIP - I've only been doing the mesh processing for a couple of weeks and only a week ago decided to create my own library, so I've only just fleshed this out. Once I'm happy with the overall shape, and I think it has shaped up nicely, I will move all this mesh stuff over to my
decomplect.ion namespace/github repository and will add unit tests.