godot/servers/rendering/renderer_scene_occlusion_cull.h
lawnjelly 691854d589 Jitter raster occlusion camera to reduce false positives.
Due to the low resolution of the occlusion buffer, small gaps between occluders can be closed and incorrectly occlude instances which should show through the gaps. To ameliorate this problem, this PR jitters the occlusion buffer over time, making it more likely an instance will be seen through a gap. This is used in conjunction with an occlusion timer per instance, to prevent instances flickering on and off rapidly.
2024-04-03 12:18:45 +01:00

241 lines
8.5 KiB
C++

/**************************************************************************/
/* renderer_scene_occlusion_cull.h */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
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#ifndef RENDERER_SCENE_OCCLUSION_CULL_H
#define RENDERER_SCENE_OCCLUSION_CULL_H
#include "core/math/projection.h"
#include "core/templates/local_vector.h"
#include "servers/rendering_server.h"
class RendererSceneOcclusionCull {
protected:
static RendererSceneOcclusionCull *singleton;
public:
class HZBuffer {
protected:
static const Vector3 corners[8];
LocalVector<float> data;
LocalVector<Size2i> sizes;
LocalVector<float *> mips;
RID debug_texture;
Ref<Image> debug_image;
PackedByteArray debug_data;
float debug_tex_range = 0.0f;
uint64_t occlusion_frame = 0;
Size2i occlusion_buffer_size;
_FORCE_INLINE_ bool _is_occluded(const real_t p_bounds[6], const Vector3 &p_cam_position, const Transform3D &p_cam_inv_transform, const Projection &p_cam_projection, real_t p_near) const {
if (is_empty()) {
return false;
}
Vector3 closest_point = p_cam_position.clamp(Vector3(p_bounds[0], p_bounds[1], p_bounds[2]), Vector3(p_bounds[3], p_bounds[4], p_bounds[5]));
if (closest_point == p_cam_position) {
return false;
}
Vector3 closest_point_view = p_cam_inv_transform.xform(closest_point);
if (closest_point_view.z > -p_near) {
return false;
}
float min_depth = -closest_point_view.z * 0.95f;
Vector2 rect_min = Vector2(FLT_MAX, FLT_MAX);
Vector2 rect_max = Vector2(FLT_MIN, FLT_MIN);
for (int j = 0; j < 8; j++) {
const Vector3 &c = RendererSceneOcclusionCull::HZBuffer::corners[j];
Vector3 nc = Vector3(1, 1, 1) - c;
Vector3 corner = Vector3(p_bounds[0] * c.x + p_bounds[3] * nc.x, p_bounds[1] * c.y + p_bounds[4] * nc.y, p_bounds[2] * c.z + p_bounds[5] * nc.z);
Vector3 view = p_cam_inv_transform.xform(corner);
Plane vp = Plane(view, 1.0);
Plane projected = p_cam_projection.xform4(vp);
float w = projected.d;
if (w < 1.0) {
rect_min = Vector2(0.0f, 0.0f);
rect_max = Vector2(1.0f, 1.0f);
break;
}
Vector2 normalized = Vector2(projected.normal.x / w * 0.5f + 0.5f, projected.normal.y / w * 0.5f + 0.5f);
rect_min = rect_min.min(normalized);
rect_max = rect_max.max(normalized);
}
rect_max = rect_max.min(Vector2(1, 1));
rect_min = rect_min.max(Vector2(0, 0));
int mip_count = mips.size();
Vector2 screen_diagonal = (rect_max - rect_min) * sizes[0];
float size = MAX(screen_diagonal.x, screen_diagonal.y);
float l = Math::ceil(Math::log2(size));
int lod = CLAMP(l, 0, mip_count - 1);
const int max_samples = 512;
int sample_count = 0;
bool visible = true;
for (; lod >= 0; lod--) {
int w = sizes[lod].x;
int h = sizes[lod].y;
int minx = CLAMP(rect_min.x * w - 1, 0, w - 1);
int maxx = CLAMP(rect_max.x * w + 1, 0, w - 1);
int miny = CLAMP(rect_min.y * h - 1, 0, h - 1);
int maxy = CLAMP(rect_max.y * h + 1, 0, h - 1);
sample_count += (maxx - minx + 1) * (maxy - miny + 1);
if (sample_count > max_samples) {
return false;
}
visible = false;
for (int y = miny; y <= maxy; y++) {
for (int x = minx; x <= maxx; x++) {
float depth = mips[lod][y * w + x];
if (depth > min_depth) {
visible = true;
break;
}
}
if (visible) {
break;
}
}
if (!visible) {
return true;
}
}
return !visible;
}
public:
static bool occlusion_jitter_enabled;
bool is_empty() const;
virtual void clear();
virtual void resize(const Size2i &p_size);
void update_mips();
// Thin wrapper around _is_occluded(),
// allowing occlusion timers to delay the disappearance
// of objects to prevent flickering when using jittering.
_FORCE_INLINE_ bool is_occluded(const real_t p_bounds[6], const Vector3 &p_cam_position, const Transform3D &p_cam_inv_transform, const Projection &p_cam_projection, real_t p_near, uint64_t &r_occlusion_timeout) const {
bool occluded = _is_occluded(p_bounds, p_cam_position, p_cam_inv_transform, p_cam_projection, p_near);
// Special case, temporal jitter disabled,
// so we don't use occlusion timers.
if (!occlusion_jitter_enabled) {
return occluded;
}
if (!occluded) {
//#define DEBUG_RASTER_OCCLUSION_JITTER
#ifdef DEBUG_RASTER_OCCLUSION_JITTER
r_occlusion_timeout = occlusion_frame + 1;
#else
r_occlusion_timeout = occlusion_frame + 9;
#endif
} else if (r_occlusion_timeout) {
// Regular timeout, allow occlusion culling
// to proceed as normal after the delay.
if (occlusion_frame >= r_occlusion_timeout) {
r_occlusion_timeout = 0;
}
}
return occluded && !r_occlusion_timeout;
}
RID get_debug_texture();
const Size2i &get_occlusion_buffer_size() const { return occlusion_buffer_size; }
virtual ~HZBuffer(){};
};
static RendererSceneOcclusionCull *get_singleton() { return singleton; }
void _print_warning() {
WARN_PRINT_ONCE("Occlusion culling is disabled at build-time.");
}
virtual bool is_occluder(RID p_rid) { return false; }
virtual RID occluder_allocate() { return RID(); }
virtual void occluder_initialize(RID p_occluder) {}
virtual void free_occluder(RID p_occluder) { _print_warning(); }
virtual void occluder_set_mesh(RID p_occluder, const PackedVector3Array &p_vertices, const PackedInt32Array &p_indices) { _print_warning(); }
virtual void add_scenario(RID p_scenario) {}
virtual void remove_scenario(RID p_scenario) {}
virtual void scenario_set_instance(RID p_scenario, RID p_instance, RID p_occluder, const Transform3D &p_xform, bool p_enabled) { _print_warning(); }
virtual void scenario_remove_instance(RID p_scenario, RID p_instance) { _print_warning(); }
virtual void add_buffer(RID p_buffer) { _print_warning(); }
virtual void remove_buffer(RID p_buffer) { _print_warning(); }
virtual HZBuffer *buffer_get_ptr(RID p_buffer) {
return nullptr;
}
virtual void buffer_set_scenario(RID p_buffer, RID p_scenario) { _print_warning(); }
virtual void buffer_set_size(RID p_buffer, const Vector2i &p_size) { _print_warning(); }
virtual void buffer_update(RID p_buffer, const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal) {}
virtual RID buffer_get_debug_texture(RID p_buffer) {
_print_warning();
return RID();
}
virtual void set_build_quality(RS::ViewportOcclusionCullingBuildQuality p_quality) {}
RendererSceneOcclusionCull() {
singleton = this;
};
virtual ~RendererSceneOcclusionCull() {
singleton = nullptr;
};
};
#endif // RENDERER_SCENE_OCCLUSION_CULL_H