OPC_Picking.cpp

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/*
 *      OPCODE - Optimized Collision Detection
 *      Copyright (C) 2001 Pierre Terdiman
 *      Homepage: http://www.codercorner.com/Opcode.htm
 */



// Precompiled Header
#include "Stdafx.h"

using namespace Opcode;

#ifdef OPC_RAYHIT_CALLBACK

/*
        Possible RayCollider usages:
        - boolean query (shadow feeler)
        - closest hit
        - all hits
        - number of intersection (boolean)

*/

bool Opcode::SetupAllHits(RayCollider& collider, CollisionFaces& contacts)
{
        struct Local
        {
                static void AllContacts(const CollisionFace& hit, void* user_data)
                {
                        CollisionFaces* CF = (CollisionFaces*)user_data;
                        CF->AddFace(hit);
                }
        };

        collider.SetFirstContact(false);
        collider.SetHitCallback(Local::AllContacts);
        collider.SetUserData(&contacts);
        return true;
}

bool Opcode::SetupClosestHit(RayCollider& collider, CollisionFace& closest_contact)
{
        struct Local
        {
                static void ClosestContact(const CollisionFace& hit, void* user_data)
                {
                        CollisionFace* CF = (CollisionFace*)user_data;
                        if(hit.mDistance<CF->mDistance) *CF = hit;
                }
        };

        collider.SetFirstContact(false);
        collider.SetHitCallback(Local::ClosestContact);
        collider.SetUserData(&closest_contact);
        closest_contact.mDistance = MAX_FLOAT;
        return true;
}

bool Opcode::SetupShadowFeeler(RayCollider& collider)
{
        collider.SetFirstContact(true);
        collider.SetHitCallback(null);
        return true;
}

bool Opcode::SetupInOutTest(RayCollider& collider)
{
        collider.SetFirstContact(false);
        collider.SetHitCallback(null);
        // Results with collider.GetNbIntersections()
        return true;
}

bool Opcode::Picking(
CollisionFace& picked_face,
const Ray& world_ray, const Model& model, const Matrix4x4* world,
float min_dist, float max_dist, const Point& view_point, CullModeCallback callback, void* user_data)
{
        struct Local
        {
                struct CullData
                {
                        CollisionFace*                  Closest;
                        float                                   MinLimit;
                        CullModeCallback                Callback;
                        void*                                   UserData;
                        Point                                   ViewPoint;
                        const MeshInterface*    IMesh;
                };

                // Called for each stabbed face
                static void RenderCullingCallback(const CollisionFace& hit, void* user_data)
                {
                        CullData* Data = (CullData*)user_data;

                        // Discard face if we already have a closer hit
                        if(hit.mDistance>=Data->Closest->mDistance)     return;

                        // Discard face if hit point is smaller than min limit. This mainly happens when the face is in front
                        // of the near clip plane (or straddles it). If we keep the face nonetheless, the user can select an
                        // object that he may not even be able to see, which is very annoying.
                        if(hit.mDistance<=Data->MinLimit)       return;

                        // This is the index of currently stabbed triangle.
                        udword StabbedFaceIndex = hit.mFaceID;

                        // We may keep it or not, depending on backface culling
                        bool KeepIt = true;

                        // Catch *render* cull mode for this face
                        CullMode CM = (Data->Callback)(StabbedFaceIndex, Data->UserData);

                        if(CM!=CULLMODE_NONE)   // Don't even compute culling for double-sided triangles
                        {
                                // Compute backface culling for current face

                                VertexPointers VP;
                                Data->IMesh->GetTriangle(VP, StabbedFaceIndex);
                                if(VP.BackfaceCulling(Data->ViewPoint))
                                {
                                        if(CM==CULLMODE_CW)             KeepIt = false;
                                }
                                else
                                {
                                        if(CM==CULLMODE_CCW)    KeepIt = false;
                                }
                        }

                        if(KeepIt)      *Data->Closest = hit;
                }
        };

        RayCollider RC;
        RC.SetMaxDist(max_dist);
        RC.SetTemporalCoherence(false);
        RC.SetCulling(false);           // We need all faces since some of them can be double-sided
        RC.SetFirstContact(false);
        RC.SetHitCallback(Local::RenderCullingCallback);

        picked_face.mFaceID             = INVALID_ID;
        picked_face.mDistance   = MAX_FLOAT;
        picked_face.mU                  = 0.0f;
        picked_face.mV                  = 0.0f;

        Local::CullData Data;
        Data.Closest                    = &picked_face;
        Data.MinLimit                   = min_dist;
        Data.Callback                   = callback;
        Data.UserData                   = user_data;
        Data.ViewPoint                  = view_point;
        Data.IMesh                              = model.GetMeshInterface();

        if(world)
        {
                // Get matrices
                Matrix4x4 InvWorld;
                InvertPRMatrix(InvWorld, *world);

                // Compute camera position in mesh space
                Data.ViewPoint *= InvWorld;
        }

        RC.SetUserData(&Data);
        if(RC.Collide(world_ray, model, world))
        {
                return picked_face.mFaceID!=INVALID_ID;
        }
        return false;
}

#endif