GR_PrimTetra.h

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#ifndef __GR_PrimTetra__
#define __GR_PrimTetra__

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

class RV_Geometry;
class RV_ShaderBlock;
class RV_ShaderVariableSet;

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.
///
/// The tetra is drawn in the Vulkan viewport using Houdini's builtin polygon
/// surface shaders (material/VK/psurf_*.prog), so it picks up materials,
/// lighting, shadows and object picking like any other surface.
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;

    /// Called for each decoration (point markers, numbers, etc) that is
    /// enabled in the display options.
    void renderDecoration(
            RE_RenderContext r,
            GR_Decoration decor,
            const GR_DecorationParms &p) override;
    int renderPick(
            RE_RenderContext r,
            const GR_DisplayOption *opt,
            unsigned int pick_type,
            GR_PickStyle pick_style,
            bool has_pick_map) override;

    /// The builtin shader programs used to draw the tetra.
    enum ShaderType
    {
        SHADER_HEADLIGHT,
        SHADER_MATERIAL,
        SHADER_CONSTANT,
        SHADER_WIREFRAME,
        SHADER_OBJECT_PICK,
        SHADER_MATTE,
        SHADER_DEPTH,
        SHADER_DEPTH_CASCADING,
        SHADER_DEPTH_CUBE,
        SHADER_DEPTH_CASCADING_SINGLE,
        SHADER_DEPTH_CUBE_SINGLE,

        NUM_SHADERS
    };

private:
    /// Draw the triangles with the given shader.
    void drawSurface(
            RE_RenderContext r,
            ShaderType shader_type,
            GR_RenderFlags flags,
            const GR_DrawParms &dp);
    /// Draw the edges, either as wireframe or blended over the surface.
    void drawWire(RE_RenderContext r, bool wire_over, const GR_DrawParms &dp);

    int myID;
    /// GPU buffers and connectivity for the tetra.
    UT_UniquePtr<RV_Geometry> myGeo;
    /// The tetra's primitive number.
    int myPrimIndex;

    /// Descriptor sets holding the per-object uniforms (glH_Object). One per
    /// shader, as the shaders may have different set layouts.
    UT_UniquePtr<RV_ShaderVariableSet> myObjectSets[NUM_SHADERS];

    /// Per-object uniform blocks (glH_Object), shared by all shaders. A block
    /// can't change between draws in the same render pass, so the surface and
    /// wire, which may be drawn in the same pass, each have their own.
    UT_UniquePtr<RV_ShaderBlock> mySurfaceBlock;
    UT_UniquePtr<RV_ShaderBlock> myWireBlock;
};

} // namespace HDK_Sample

#endif