Improved flexible cloth collision processing method

Abstract

The invention relates to an improved flexible cloth collision processing method which is characterized by establishing a quad bounding box tree according to the spatial relation for the triangular meshes of the cloth, and using an AABB bounding box; at a rough detection stage, by combining the quad bounding box tree, eliminating the regions which impossibly intersect with each other further by an improved continuous vector cone method than by a conventional method; at an accurate detection stage, implementing a set of reasonable primitive detection strategy on the primitives which possibly intersect with each other within a step length, and adding penetration detection and processing in the detection process for improving the accuracy as far as possible and ensuring no penetration; and on the collision response mode, processing by an impulse compensation model and a contact surface mechanical model. The method comprises the following steps: (1) establishing a quad bounding box tree according to the spatial relation for the triangular meshes of the cloth; (2) by combining the quad bounding box tree, eliminating the regions which impossibly intersect with each other by an improved continuous vector cone method; (3) implementing a primitive detection strategy on the primitive pairs which possibly intersect with each other in a step length, and adding penetration detection and processing in the detection strategy; and (4) for the detected collision pairs, computing the collision response by adopting a combined mode of an impulse compensation model and a contact surface mechanical model.

Description

technical field [0001] The invention relates to an improved flexible fabric collision processing method, which belongs to the technical field of flexible fabric simulation. Background technique [0002] Fabric self-collision, collision detection and response between fabric and irregular objects is an important research content in flexible fabric simulation. The collision between the various parts of the fabric itself is called self-collision; the collision between the fabric and other external objects, such as the collision with the table, human body, etc., is called other collision. The process of collision processing is divided into rough detection stage, precise detection stage and collision response stage. [0003] In previous research work, Provot proposed a method combining the normal vector cone method and the bounding box tree in the rough detection stage to eliminate impossible intersecting areas on a large scale. [0004] In the precise detection stage of primiti...

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Problems solved by technology

[0007] (1) In the application of the normal vector cone method combined with the quadrilateral bounding box tree, the spatial continuity is not fully utilized, and each detection only detects the normal vector cone angle of the parent node

Since the triangular patch areas contained in each of the two sub-nodes of the quadtree are adjacent, as long as they are adjacent, the normal vector cone method can be used for pruning. Otherwise, the trajectory bounding boxes of the adjacent areas must be determined to intersect. , but in fact they do not necessarily collide, which results in redundant detection

[0008] (2) In the traditional normal vector cone method, there are some errors in the bottom-up method of calculating the cone axis and cone angle of the parent node from the child node, and the situation that the half cone angle of the child node is greater than or equal to π / 2 is not considered; And it does not take into account the continuous trajectory of the triangle surface

[0009] (3) Within a collision step, accurately detect the pairs of primitives that may collide. At present, the existing detection strategies have their own advantages and disadvantages. The methods of Provot and Bridson are more efficient, but the accuracy is not high, and most of them have penetration occurs, the Selle method guarantees correctness at the expense of efficiency

[0010] (4) In the form of the collision response, the original method either directly modifies the velocity of the particle or modifies its velocity in the form of impulse compensation when processing the collision primitive, which does not affect the force on the collision surface primitive ( support and friction) for direct simulation

The original response method is not obvious for the simulation of friction, and cannot meet the needs of some special simulation scenarios

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