nurbs

How to combine Rational B-spline Surfaces?

由 对着背影说爱祢 提交于 2020-07-23 06:43:25
问题 How to combine Rational B-spline Surfaces into one or fewer? How do metrics such as tolerance, u/v degree, u/v span influence the final result, if any? 回答1: In general, there is no way to create a single rational B-spline surface as the exact merge result of the 4 input rational B-spline surfaces. So, you will have to settle with an approximation. Consequently, there is no need for this approximating surface to be rational. The approximation schemes typically are divided into two categories:

How to combine Rational B-spline Surfaces?

由 元气小坏坏 提交于 2020-07-23 06:42:27
问题 How to combine Rational B-spline Surfaces into one or fewer? How do metrics such as tolerance, u/v degree, u/v span influence the final result, if any? 回答1: In general, there is no way to create a single rational B-spline surface as the exact merge result of the 4 input rational B-spline surfaces. So, you will have to settle with an approximation. Consequently, there is no need for this approximating surface to be rational. The approximation schemes typically are divided into two categories:

How to combine Rational B-spline Surfaces?

由 ╄→尐↘猪︶ㄣ 提交于 2020-07-23 06:40:55
问题 How to combine Rational B-spline Surfaces into one or fewer? How do metrics such as tolerance, u/v degree, u/v span influence the final result, if any? 回答1: In general, there is no way to create a single rational B-spline surface as the exact merge result of the 4 input rational B-spline surfaces. So, you will have to settle with an approximation. Consequently, there is no need for this approximating surface to be rational. The approximation schemes typically are divided into two categories:

Rendering NURBS surface in webGL

由 久未见 提交于 2020-07-15 09:11:05
问题 I need some help with rendering a NURBS surface in webGL. Some days ago our professor assigned us to draw with NURBS a flag and to animate it. We have to use webGL (and cannot trhee.js...). I have no idea on how to proceed (even though I know the theory about NURBS and tessellation more or less). Any hint? Disclaimer: I'm not asking for a solution. It's against the rules and I want to get it myself. I just need to be pointed on the right direction. Thanks in advance 回答1: Just because you can

Convert BSpline Curve to Arc Spline in OpenCASCADE

由 那年仲夏 提交于 2020-04-09 12:58:26
Abstract. The paper based on OpenCASCADE algorithms to approximate the NURBS curve to arc spline. The method is most useful in numerical control to drive the cutter along straight line or circular paths. Or in the shipbuilding industry to manufacture section bar for cold frame bender. Key Words. NURBS, Biarc approximation, arc spline, 1. Introduction 在数控加工CNC领域，通常需要用尽量少段数的圆弧和直线段来对曲线进行拟合。有的数控绘图机也只有直线和圆弧插补器，即只能绘制直线和圆弧，所以也需要将自由曲线转换成直线和圆弧来进行绘制。在船舶制造方面，如肋骨冷弯机只有两种状态：弯和不弯，也只能加工出直线和圆弧，所以也需要将曲面型材的弯曲信息转换成肋骨冷弯机能加工的数据。如下图所示为型材模型及其基线： Figure 1. 型材模型及基线 Figure 2. 肋骨冷弯机 如上图所示，型材都是直线的，通过弯曲加工出曲线效果

NURBS in the OpenGL Graphics Pipeline

由 ﹥＞﹥吖頭↗ 提交于 2019-12-25 02:43:26
问题 I'm curious about how NURBS are rendered in GPU's / the OpenGL graphics pipeline. I understand there are various calls within OpenGL and GLUT for easily rendering NURBS objects from a coding perspective using glMap and glMapGrid, but what I don't get is the process OpenGL goes through to do this. The idea behind NURBS is using curves to define surfaces, whereas the graphics pipeline appears to be build around triangle rasterization and triangle meshes, whereas NURBS are based around Bezier

NURBS in the OpenGL Graphics Pipeline

由 こ雲淡風輕ζ 提交于 2019-12-25 02:42:39
问题 I'm curious about how NURBS are rendered in GPU's / the OpenGL graphics pipeline. I understand there are various calls within OpenGL and GLUT for easily rendering NURBS objects from a coding perspective using glMap and glMapGrid, but what I don't get is the process OpenGL goes through to do this. The idea behind NURBS is using curves to define surfaces, whereas the graphics pipeline appears to be build around triangle rasterization and triangle meshes, whereas NURBS are based around Bezier

How can I create a 3D cubic-bezier curved triangle from 3D points in Three.js?

由 跟風遠走 提交于 2019-12-21 21:54:10
问题 Following this topic, I am trying to generate a 3D curved triangle as a NURBS surface, but I don't understand how to set up my 3D points to do that. Here is the current implementation : var edges = this.getEdges(), // An edge is a line following 4 dots as a bezier curve. dots = self.getDotsFromEdges(edges), // Get all dots in order for building the surface. ctrlPoints = [ // Is generated only once before, but copy-pasted here for this sample code. [ new THREE.Vector4(0, 0, 0, 1), new THREE

How to create a cubic bezier curve when given N points in 3D?

由 ぐ巨炮叔叔 提交于 2019-12-21 02:56:18
问题 So I need to find out where the control points would be for a cubic bezier curve when only knowing points on the curve, the points can lie in 3D. It would be ideal if I could do this for any number of points on the curve. Most of what I have found deals only with 2D, or only for 4 points. 回答1: Let me see if I understand you: you want an interpolating Bezier curve, going through a given set of points P0 P1 ... but drawn as Bezier curves, with a function like bezier4( nstep, Pj, Cj, Dj, Pj+1 )

Maya transform node not appearing in list

由 时光怂恿深爱的人放手 提交于 2019-12-13 00:54:23
问题 The Maya python code below gives a nurbs boolean surface by first taking the difference of two nurbs spheres, nurbsSphere1 and nurbsSphere2, to give the nurbs surface nurbsBooleanSurface1. It then takes the difference of this surface and a third sphere, nurbsSphere3. The result, as seen in the outliner, is the three nurbs spheres plus a surfaceVarGroup, nurbsBooleanSurface1, which 'parents' three transform nodes nurbsBooleanSurface1_1, nurbsBooleanSurface1_2 and nurbsBooleanSurface1_3. import
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