Plan depth export through document renderer

src/paint_renderer/compositor.cpp

@@ -683,6 +683,57 @@ export_document_frame_equirectangular_png(DocumentFrameCompositeRequest request)
     return export_document_frame_equirectangular_png(composite.value());
 }
 
+pp::foundation::Result<DocumentDepthExportRenderPlan> plan_document_depth_export_render(
+    DocumentDepthExportRenderPlanRequest request) noexcept
+{
+    if (request.document == nullptr) {
+        return pp::foundation::Result<DocumentDepthExportRenderPlan>::failure(
+            pp::foundation::Status::invalid_argument("document depth export request requires a document"));
+    }
+
+    if (request.frame_index >= request.document->frames().size()) {
+        return pp::foundation::Result<DocumentDepthExportRenderPlan>::failure(
+            pp::foundation::Status::out_of_range("document depth export frame index is outside the document"));
+    }
+
+    const auto output_pixels = expected_pixel_count(request.output_extent);
+    if (!output_pixels) {
+        return pp::foundation::Result<DocumentDepthExportRenderPlan>::failure(output_pixels.status());
+    }
+
+    DocumentDepthExportRenderPlan plan;
+    plan.output_extent = request.output_extent;
+    plan.merged_face_draw_count = pp::document::cube_face_count;
+    plan.visited_layer_count = request.document->layers().size();
+
+    for (const auto& layer : request.document->layers()) {
+        if (!layer.visible || layer.opacity == 0.0F || request.frame_index >= layer.frames.size()) {
+            continue;
+        }
+
+        ++plan.visible_layer_count;
+        std::array<bool, pp::document::cube_face_count> layer_faces {};
+        const auto& frame = layer.frames[request.frame_index];
+        for (const auto& payload : frame.face_pixels) {
+            if (payload.face_index >= pp::document::cube_face_count) {
+                return pp::foundation::Result<DocumentDepthExportRenderPlan>::failure(
+                    pp::foundation::Status::out_of_range("document depth export face index is outside the cube"));
+            }
+
+            layer_faces[payload.face_index] = true;
+            ++plan.face_payload_count;
+        }
+
+        for (const auto has_payload : layer_faces) {
+            if (has_payload) {
+                ++plan.layer_depth_draw_count;
+            }
+        }
+    }
+
+    return pp::foundation::Result<DocumentDepthExportRenderPlan>::success(plan);
+}
+
 pp::foundation::Result<DocumentLayerEquirectangularPngExportResult>
 export_document_layers_equirectangular_pngs(DocumentLayerEquirectangularPngExportRequest request)
 {

src/paint_renderer/compositor.h

@@ -156,6 +156,29 @@ struct DocumentFrameEquirectangularPngExportResult {
     std::size_t composited_layer_face_count = 0;
 };
 
+struct DocumentDepthExportRenderPlanRequest {
+    const pp::document::CanvasDocument* document = nullptr;
+    std::size_t frame_index = 0;
+    pp::renderer::Extent2D output_extent {
+        .width = 1024,
+        .height = 1024,
+    };
+};
+
+struct DocumentDepthExportRenderPlan {
+    pp::renderer::Extent2D output_extent {
+        .width = 1024,
+        .height = 1024,
+    };
+    std::size_t merged_face_draw_count = 0;
+    std::size_t layer_depth_draw_count = 0;
+    std::size_t visited_layer_count = 0;
+    std::size_t visible_layer_count = 0;
+    std::size_t face_payload_count = 0;
+    bool uses_perspective_camera = true;
+    bool requires_renderer_readback = true;
+};
+
 struct DocumentLayerEquirectangularPngExportRequest {
     const pp::document::CanvasDocument* document = nullptr;
     std::size_t frame_index = 0;
@@ -232,6 +255,9 @@ export_document_frame_equirectangular_png(const DocumentFrameCompositeResult& co
 [[nodiscard]] pp::foundation::Result<DocumentFrameEquirectangularPngExportResult>
 export_document_frame_equirectangular_png(DocumentFrameCompositeRequest request);
 
+[[nodiscard]] pp::foundation::Result<DocumentDepthExportRenderPlan> plan_document_depth_export_render(
+    DocumentDepthExportRenderPlanRequest request) noexcept;
+
 [[nodiscard]] pp::foundation::Result<DocumentLayerEquirectangularPngExportResult>
 export_document_layers_equirectangular_pngs(DocumentLayerEquirectangularPngExportRequest request);