BcM Posted June 30, 2017 Share Posted June 30, 2017 Hello, I just started with Houdini, and tried to make a sweep kinda thingy with VEX (part of a larger plan). I cannot seem to figure out how to get around this problem. When I scatter points around my existing point, they are not rotated, I assume because the points I drew have no normal whatsoever. I want them like the red lines in the attachment. I tried to do a lookat from one point to the next, but I cannot figure out what to do next. //define variables float twopi = 3.14159 * 2; float theta = 0; float step_angle = twopi / (float)85; float x, z; vector pos; matrix n; // define line rotation // add points while(theta < twopi) { x = @P.x + cos(theta) * .05; z = @P.z + sin(theta) * .05; pos = set(x, @P.y, z); addpoint(0,pos); theta += step_angle; } Any help would be appreciated. Quote Link to comment Share on other sites More sharing options...

f1480187 Posted July 3, 2017 Share Posted July 3, 2017 Do you want it to be perpendicular to the plane created by two edges with angle? For any non-corner case you can compute rotation matrix: // Point wrangle. // Compute matrix aligned with plane created by two edges. vector e0 = point(0, "P", @ptnum-1) - @P; vector e1 = point(0, "P", @ptnum+1) - @P; vector y = normalize(e0 + e1); vector z = normalize(cross(e0, e1)); vector x = normalize(cross(z, y)); 3@r = set(x, y, z); After that, you may use it in your point creation loop like this: // Create position on circle centered at the origin. // Scale it by radius. Rotate it by rotation matrix. // Translate it to desired location. set(cos(theta), sin(theta), 0) * radius * r + pivot It's an example expression, not a final code. From your code, value .05 can be used as a radius, @P can be a pivot and r is a matrix computed by the snippet above. There are common cases where it will not work. You should decide which orientation to prefer from infinite possible variants: End points. One or both edges has zero length. Angle between edges is 0 or PI align_circles_to_curve.hipnc 1 Quote Link to comment Share on other sites More sharing options...

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