Add Chromium-only Blender WebEngine parity work

blender-5.2.0/source/blender/render/intern/zbuf.h

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+/* SPDX-FileCopyrightText: 2023 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup render
+ */
+
+#pragma once
+
+namespace blender {
+
+/** Span fill in method, is also used to localize data for Z-buffering. */
+struct ZSpan {
+  int rectx, recty; /* range for clipping */
+
+  int miny1, maxy1, miny2, maxy2;             /* actual filled in range */
+  const float *minp1, *maxp1, *minp2, *maxp2; /* vertex pointers detect min/max range in */
+  float *span1, *span2;
+};
+
+/**
+ * Each Z-buffer has coordinates transformed to local rect coordinates, so we can simply clip.
+ */
+void zbuf_alloc_span(struct ZSpan *zspan, int rectx, int recty);
+void zbuf_free_span(struct ZSpan *zspan);
+
+/**
+ * Scan-convert for strand triangles, calls function for each x, y coordinate
+ * and gives UV barycentrics and z.
+ */
+void zspan_scanconvert(struct ZSpan *zspan,
+                       void *handle,
+                       float *v1,
+                       float *v2,
+                       float *v3,
+                       void (*func)(void *, int, int, float, float));
+
+}  // namespace blender