Function tryCreateTri

src/traces/isosurface/convert.js:398–477

(style, xyzv, abc, min, max, nPass)

    var MAX_PASS = 3;

    function tryCreateTri(style, xyzv, abc, min, max, nPass) {
        if(!nPass) nPass = 1;

        abc = [-1, -1, -1]; // Note: for the moment we override indices
        // to run faster! But it is possible to comment this line
        // to reduce the number of vertices.

        var result = false;

        var ok = [
            inRange(xyzv[0][3], min, max),
            inRange(xyzv[1][3], min, max),
            inRange(xyzv[2][3], min, max)
        ];

        if(!ok[0] && !ok[1] && !ok[2]) {
            return false;
        }

        var tryDrawTri = function(style, xyzv, abc) {
            if( // we check here if the points are in `real` iso-min/max range
                almostInFinalRange(xyzv[0][3]) &&
                almostInFinalRange(xyzv[1][3]) &&
                almostInFinalRange(xyzv[2][3])
            ) {
                drawTri(style, xyzv, abc);
                return true;
            } else if(nPass < MAX_PASS) {
                return tryCreateTri(style, xyzv, abc, vMin, vMax, ++nPass); // i.e. second pass using actual vMin vMax bounds
            }
            return false;
        };

        if(ok[0] && ok[1] && ok[2]) {
            return tryDrawTri(style, xyzv, abc) || result;
        }

        var interpolated = false;

        [
            [0, 1, 2],
            [2, 0, 1],
            [1, 2, 0]
        ].forEach(function(e) {
            if(ok[e[0]] && ok[e[1]] && !ok[e[2]]) {
                var A = xyzv[e[0]];
                var B = xyzv[e[1]];
                var C = xyzv[e[2]];

                var p1 = calcIntersection(C, A, min, max);
                var p2 = calcIntersection(C, B, min, max);

                result = tryDrawTri(style, [p2, p1, A], [-1, -1, abc[e[0]]]) || result;
                result = tryDrawTri(style, [A, B, p2], [abc[e[0]], abc[e[1]], -1]) || result;

                interpolated = true;
            }
        });