viewport_lib/renderer/stats.rs
1//! Per-frame performance counters for the viewport renderer.
2
3/// Controls the renderer's internal default behavior.
4///
5/// The host application owns playback state, time, and scene content.
6/// `RuntimeMode` tells the renderer what workload to expect so it can adjust
7/// internal defaults (e.g. picking rate) accordingly.
8#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
9#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
10pub enum RuntimeMode {
11 /// Prioritize responsiveness and picking accuracy.
12 #[default]
13 Interactive,
14 /// Prioritize steady frame pacing; picking may be throttled.
15 Playback,
16 /// Restore full quality; picking runs at full rate.
17 Paused,
18 /// Full-quality render intended for screenshot or export workflows.
19 ///
20 /// Forces `render_scale` to `max_render_scale` for the duration of the frame
21 /// and suppresses all pass-level degradation regardless of `missed_budget`.
22 /// The adaptation controller is paused; render scale resumes from
23 /// `max_render_scale` on the next non-Capture frame.
24 ///
25 /// Note: blocking until GPU work is complete (for pixel readback) is the
26 /// caller's responsibility. This mode ensures full-quality CPU-side decisions
27 /// only; it does not insert any GPU synchronisation inside the renderer.
28 Capture,
29}
30
31/// A coarse quality tier for [`PerformancePolicy`].
32///
33/// When `PerformancePolicy::preset` is `Some`, the renderer derives render scale
34/// bounds and pass-level degradation flags from the preset instead of the individual
35/// policy fields. The individual fields are still persisted so that switching back
36/// to `None` restores the previous custom configuration.
37///
38/// `target_fps` and `allow_dynamic_resolution` are always taken from the policy
39/// fields regardless of the preset.
40#[derive(Debug, Clone, Copy, PartialEq, Eq)]
41#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
42pub enum QualityPreset {
43 /// Native resolution, all passes enabled, no degradation allowed.
44 ///
45 /// Equivalent to `min_render_scale = 1.0`, `max_render_scale = 1.0`,
46 /// all `allow_*` flags false.
47 High,
48 /// Render scale [0.75, 1.0]; shadow reduction and effect throttling allowed.
49 ///
50 /// Equivalent to `min_render_scale = 0.75`, `max_render_scale = 1.0`,
51 /// `allow_shadow_reduction = true`, `allow_effect_throttling = true`.
52 Medium,
53 /// Render scale [0.5, 0.75]; all degradation paths allowed.
54 ///
55 /// Equivalent to `min_render_scale = 0.5`, `max_render_scale = 0.75`,
56 /// all `allow_*` flags true.
57 Low,
58}
59
60/// Controls what quality reductions the viewport is allowed to apply under load.
61///
62/// Set once via [`crate::ViewportRenderer::set_performance_policy`]. The internal
63/// adaptation controller reads `target_fps` and adjusts render scale within
64/// `[min_render_scale, max_render_scale]` when `allow_dynamic_resolution` is true.
65///
66/// Pass-specific flags (`allow_shadow_reduction`, `allow_volume_quality_reduction`,
67/// `allow_effect_throttling`) gate concrete quality reductions that kick in when
68/// the previous frame missed the target budget, applied in order via a tiered
69/// degradation ladder (render scale first, then shadows, then volumes, then effects).
70///
71/// Set `preset` to a [`QualityPreset`] to configure bounds and flags as a unit.
72#[derive(Debug, Clone, Copy, PartialEq)]
73#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
74pub struct PerformancePolicy {
75 /// Coarse quality tier. When `Some`, overrides `min_render_scale`,
76 /// `max_render_scale`, and all `allow_*` flags for the duration of the frame.
77 /// Set to `None` to use the individual fields directly.
78 pub preset: Option<QualityPreset>,
79 /// Target frames per second. `None` means uncapped; `missed_budget` is always `false`.
80 pub target_fps: Option<f32>,
81 /// Lower bound for dynamic render scale (e.g. 0.5 = half resolution).
82 ///
83 /// Ignored when `preset` is `Some`; the preset's bounds are used instead.
84 pub min_render_scale: f32,
85 /// Upper bound for dynamic render scale (1.0 = native).
86 ///
87 /// Ignored when `preset` is `Some`; the preset's bounds are used instead.
88 pub max_render_scale: f32,
89 /// Allow the viewport to adjust render scale automatically when budget is exceeded.
90 ///
91 /// When `false`, the internal controller is inactive and render scale can be
92 /// set manually via [`crate::ViewportRenderer::set_render_scale`].
93 ///
94 /// The controller uses `FrameStats::gpu_frame_ms` as the cost signal when GPU
95 /// timestamp queries are available (excludes vsync wait). When GPU timestamps are
96 /// unavailable it falls back to `total_frame_ms`, which reflects wall-clock frame
97 /// duration and correctly fires over-budget at low frame rates.
98 ///
99 /// **LDR path only.** Dynamic resolution applies when the scene is rendered
100 /// via [`crate::ViewportRenderer::paint_to`] or
101 /// [`crate::ViewportRenderer::paint_viewport`] (i.e.
102 /// `PostProcessSettings::enabled` is `false`). When the HDR post-processing
103 /// path is active (`render` / `render_viewport`), render scale has no effect
104 /// on output quality and the adaptation controller is suppressed.
105 /// `FrameStats::render_scale` will report 1.0 in that case.
106 pub allow_dynamic_resolution: bool,
107 /// Allow the viewport to skip the shadow pass under load.
108 ///
109 /// When `true` and the previous frame exceeded the target budget, the shadow depth
110 /// pass is skipped entirely. Shadows reappear as soon as the frame is within budget.
111 /// Ignored when `preset` is `Some`.
112 pub allow_shadow_reduction: bool,
113 /// Allow the viewport to reduce volume raymarch quality under load.
114 ///
115 /// When `true` and the previous frame exceeded the target budget, the per-volume
116 /// step size is doubled (half the number of samples), reducing GPU cost at the
117 /// cost of coarser volume appearance. Ignored when `preset` is `Some`.
118 pub allow_volume_quality_reduction: bool,
119 /// Allow the viewport to skip non-essential HDR effect passes under load.
120 ///
121 /// When `true` and the previous frame exceeded the target budget, the SSAO,
122 /// contact shadow, and bloom passes are skipped for that frame.
123 /// Ignored when `preset` is `Some`.
124 pub allow_effect_throttling: bool,
125}
126
127impl Default for PerformancePolicy {
128 fn default() -> Self {
129 Self {
130 preset: None,
131 target_fps: None,
132 min_render_scale: 0.5,
133 max_render_scale: 1.0,
134 allow_dynamic_resolution: false,
135 allow_shadow_reduction: false,
136 allow_volume_quality_reduction: false,
137 allow_effect_throttling: false,
138 }
139 }
140}
141
142/// Per-frame rendering statistics returned by [`crate::ViewportRenderer::prepare`].
143#[derive(Debug, Clone, Copy, Default)]
144pub struct FrameStats {
145 /// Total objects considered for rendering.
146 pub total_objects: u32,
147 /// Objects that passed visibility and frustum tests.
148 pub visible_objects: u32,
149 /// Objects culled by frustum or visibility.
150 pub culled_objects: u32,
151 /// Number of draw calls issued in the main pass.
152 pub draw_calls: u32,
153 /// Number of instanced batches (0 when using per-object path).
154 pub instanced_batches: u32,
155 /// Total triangles submitted to the GPU.
156 pub triangles_submitted: u64,
157 /// Number of draw calls in the shadow pass.
158 pub shadow_draw_calls: u32,
159 /// CPU time spent in `prepare()`, in milliseconds.
160 pub cpu_prepare_ms: f32,
161 /// GPU scene-pass time in milliseconds, if timestamp queries are available.
162 ///
163 /// Measured with `TIMESTAMP_QUERY` around the main scene render pass.
164 /// `None` on backends that do not support `TIMESTAMP_QUERY` (e.g. WebGL).
165 ///
166 /// Note: this value reflects the *previous* frame's GPU cost due to async
167 /// readback. The value lags by one frame and should not be used by the
168 /// adaptation controller across mode transitions.
169 pub gpu_frame_ms: Option<f32>,
170 /// Wall-clock duration since the previous `prepare()` call, in milliseconds.
171 ///
172 /// Approximates the full frame interval. Zero on the first frame.
173 pub total_frame_ms: f32,
174 /// Current internal render scale (1.0 = native resolution).
175 ///
176 /// Reflects the value tracked by the adaptation controller. Values below 1.0
177 /// cause the scene to render into a scaled intermediate texture that is
178 /// bilinearly upscaled to the surface (requires `allow_dynamic_resolution`).
179 pub render_scale: f32,
180 /// True if the last frame exceeded the target frame budget.
181 ///
182 /// Requires `target_fps` to be set in the [`PerformancePolicy`]. Always
183 /// `false` when no target is configured.
184 pub missed_budget: bool,
185 /// Bytes of geometry data uploaded to the GPU since the previous
186 /// `prepare()` call.
187 ///
188 /// Counts full buffer reallocations triggered by
189 /// [`crate::ViewportGpuResources::replace_mesh_data`] and initial uploads
190 /// via `upload_mesh_data` / `upload_mesh`. Uniform buffer writes are not
191 /// counted.
192 pub upload_bytes: u64,
193 /// True when GPU-driven culling is active this frame.
194 ///
195 /// False when the device does not support `INDIRECT_FIRST_INSTANCE` or
196 /// culling has been disabled via `disable_gpu_driven_culling()`.
197 pub gpu_culling_active: bool,
198 /// Number of instances that passed GPU culling and were submitted for drawing.
199 ///
200 /// Populated only when `gpu_culling_active` is true. `None` on the first frame
201 /// or when GPU culling is off. Lags by one frame due to async readback.
202 pub gpu_visible_instances: Option<u32>,
203
204 // --- Per-pass degradation flags ---
205 /// True when the shadow depth pass was skipped this frame.
206 ///
207 /// Set when `allow_shadow_reduction` is true and the previous frame missed
208 /// the target budget. Always false in [`RuntimeMode::Capture`].
209 pub shadows_skipped: bool,
210 /// True when volume raymarch step size was doubled this frame.
211 ///
212 /// Set when `allow_volume_quality_reduction` is true and the previous frame
213 /// missed the target budget. Always false in [`RuntimeMode::Capture`].
214 pub volume_quality_reduced: bool,
215 /// True when SSAO, contact shadows, and bloom were skipped this frame.
216 ///
217 /// Set when `allow_effect_throttling` is true and the previous frame missed
218 /// the target budget. Always false in [`RuntimeMode::Capture`].
219 pub effects_throttled: bool,
220}
221
222#[cfg(test)]
223mod tests {
224 use super::*;
225
226 #[test]
227 fn test_frame_stats_default_is_zero() {
228 let stats = FrameStats::default();
229 assert_eq!(stats.total_objects, 0);
230 assert_eq!(stats.visible_objects, 0);
231 assert_eq!(stats.culled_objects, 0);
232 assert_eq!(stats.draw_calls, 0);
233 assert_eq!(stats.instanced_batches, 0);
234 assert_eq!(stats.triangles_submitted, 0);
235 assert_eq!(stats.shadow_draw_calls, 0);
236 assert_eq!(stats.cpu_prepare_ms, 0.0);
237 assert!(stats.gpu_frame_ms.is_none());
238 assert_eq!(stats.total_frame_ms, 0.0);
239 assert_eq!(stats.render_scale, 0.0);
240 assert!(!stats.missed_budget);
241 assert_eq!(stats.upload_bytes, 0);
242 assert!(!stats.gpu_culling_active);
243 assert!(stats.gpu_visible_instances.is_none());
244 assert!(!stats.shadows_skipped);
245 assert!(!stats.volume_quality_reduced);
246 assert!(!stats.effects_throttled);
247 }
248
249 #[test]
250 fn test_runtime_mode_default_is_interactive() {
251 assert_eq!(RuntimeMode::default(), RuntimeMode::Interactive);
252 }
253
254 #[test]
255 fn test_performance_policy_default() {
256 let p = PerformancePolicy::default();
257 assert!(p.preset.is_none());
258 assert!(p.target_fps.is_none());
259 assert!(!p.allow_dynamic_resolution);
260 assert!(p.min_render_scale <= p.max_render_scale);
261 assert_eq!(p.max_render_scale, 1.0);
262 }
263}