GR_PrimTetra.h

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 * Copyright (c) 2025
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#ifndef __GR_PrimTetra__
#define __GR_PrimTetra__

#include <GUI/GUI_PrimitiveHook.h>
#include <GR/GR_Primitive.h>
#include <RE/RE_RenderContext.h>

namespace HDK_Sample
{
    
/// The primitive render hook which creates GR_PrimTetra objects.
class GR_PrimTetraHook : public GUI_PrimitiveHook
{
public:
             GR_PrimTetraHook();
            ~GR_PrimTetraHook() override;

    /// This is called when a new GR_Primitive is required for a tetra.
    /// gt_prim or geo_prim contains the GT or GEO primitive this object is being
    /// created for, depending on whether this hook is registered to capture
    /// GT or GEO primitives.
    /// info and cache_name should be passed down to the GR_Primitive
    /// constructor.
    /// processed should return GR_PROCESSED or GR_PROCESSED_NON_EXCLUSIVE if
    /// a primitive is created. Non-exclusive allows other render hooks or the
    /// native Houdini primitives to be created for the same primitive, which is
    /// useful for support hooks (drawing decorations, bounding boxes, etc). 
    GR_Primitive        *createPrimitive(const GT_PrimitiveHandle &gt_prim,
                                         const GEO_Primitive *geo_prim,
                                         const GR_RenderInfo *info,
                                         const char *cache_name,
                                         GR_PrimAcceptResult &processed
                                         ) override;
};
    
/// Primitive object that is created by GR_PrimTetraHook whenever a
/// tetrahedron primitive is found. This object can be persistent between
/// renders, though display flag changes or navigating though SOPs can cause
/// it to be deleted and recreated later.
class GR_PrimTetra : public GR_Primitive
{
public:
                         GR_PrimTetra(const GR_RenderInfo *info,
                                      const char *cache_name,
                                      const GEO_Primitive *prim);
                        ~GR_PrimTetra() override;

    const char         *className() const override { return "GR_PrimTetra"; }

    /// See if the tetra primitive can be consumed by this primitive. Only
    /// tetra from the same detail will ever be passed in. 
    GR_PrimAcceptResult acceptPrimitive(GT_PrimitiveType t,
                                        int geo_type,
                                        const GT_PrimitiveHandle &ph,
                                        const GEO_Primitive *prim) override;

    /// Called whenever the parent detail is changed, draw modes are changed,
    /// selection is changed, or certain volatile display options are changed
    /// (such as level of detail).
    void                update(RE_RenderContext           r,
                               const GT_PrimitiveHandle  &primh,
                               const GR_UpdateParms      &p) override;

    /// Called whenever the primitive is required to render, which may be more
    /// than one time per viewport redraw (beauty, shadow passes, wireframe-over)
    /// It also may be called outside of a viewport redraw to do picking of the
    /// geometry.
    void                render(RE_RenderContext        r,
                               GR_RenderMode           render_mode,
                               GR_RenderFlags          flags,
                               GR_DrawParms            dp) override;
    void                renderDecoration(
                                RE_RenderContext r,
                                GR_Decoration decor,
                                const GR_DecorationParms &parms) override;
    int                 renderPick(RE_RenderContext r,
                                   const GR_DisplayOption *opt,
                                   unsigned int pick_type,
                                   GR_PickStyle pick_style,
                                   bool has_pick_map) override;
private:
    int myID;
    RE_Geometry *myGeo;
    bool myInstancedFlag;
};



} // End HDK_Sample namespace.

#endif