Planeta again

scripts/icosahedron_tables.py

@@ -126,9 +126,9 @@ def distance(a, b):
 
 # Edge lengths vs subdiv level
 
-edge_length_min = [2.0*sin(0.5*acot(0.5) * 0.5**x) for x in range(0, 10)]
+edge_length_min = [2.0*sin(0.5*acot(0.5) * 0.5**x) for x in range(0, 24)]
 
-print("inline constexpr std::array<float, 10> const gc_icoMinEdgeVsSubdiv\n"
+print("inline constexpr std::array<float, 24> const gc_icoMinEdgeVsSubdiv\n"
       + "{\n"
       + "    " + ", ".join(nstr_float(edge_length) for edge_length in edge_length_min) + "\n"
       + "};\n")
@@ -143,7 +143,7 @@ def distance(a, b):
     ( cxa,   -sya,    hei)
 )
 
-for _ in range(0, 10):
+for _ in range(0, 24):
 
     edge_length_max.append(distance(tri[0], tri[1]))
 
@@ -154,7 +154,7 @@ def distance(a, b):
         norm(mid(tri[2], tri[0]))
     )
 
-print("inline constexpr std::array<float, 10> const gc_icoMaxEdgeVsSubdiv\n"
+print("inline constexpr std::array<float, 24> const gc_icoMaxEdgeVsSubdiv\n"
       + "{\n"
       + "    " + ", ".join(nstr_float(edge_length) for edge_length in edge_length_max) + "\n"
       + "};\n")
@@ -165,9 +165,9 @@ def distance(a, b):
 # If identical towers were built on the two vertices spanning an edge, this is how high each tower
 # needs to be in order to see each other over the horizon.
 #  = exsec(0.5*acot(0.5) * levels)
-tower_heights = [sec(0.5*acot(0.5) * 0.5**x ) - 1 for x in range(0, 10)]
+tower_heights = [sec(0.5*acot(0.5) * 0.5**x ) - 1 for x in range(0, 24)]
 
-print("inline constexpr std::array<float, 10> const gc_icoTowerOverHorizonVsSubdiv\n"
+print("inline constexpr std::array<float, 24> const gc_icoTowerOverHorizonVsSubdiv\n"
       + "{\n"
       + "    " + ", ".join(nstr_float(edge_length) for edge_length in tower_heights) + "\n"
       + "};\n")

src/osp/core/array_view.h

@@ -26,6 +26,7 @@
 
 // IWYU pragma: begin_exports
 #include <Corrade/Containers/ArrayView.h>
+#include <Corrade/Containers/StridedArrayView.h>
 // IWYU pragma: end_exports
 
 #include <iterator>
@@ -36,34 +37,52 @@ namespace osp
 using Corrade::Containers::ArrayView;
 using Corrade::Containers::arrayView;
 
+/**
+ * @brief Wraps a Corrade ArrayView or StridedArrayView to use as a 2D array of equally sized rows
+ */
 template<typename T>
 struct ArrayView2DWrapper
 {
-    constexpr ArrayView<T> row(std::size_t const index) const noexcept
+    // yes, I know that StridedArrayView2D exists, but ".row(...)" is more explicit
+
+    constexpr T row(std::size_t const columnIndex) const noexcept
     {
-        return view.sliceSize(index * columns, columns);
+        return view.sliceSize(columnIndex * rowSize, rowSize);
     }
 
-    ArrayView<T> view;
-    std::size_t columns;
+    T view;
+    std::size_t rowSize; ///< Size of each row, same as the number of columns
 };
 
+/**
+ * @brief Returns an interface that treats an ArrayView as a 2D array of equally sized rows.
+ *
+ * This overload auto-converts ArrayView-compatible types.
+ */
+template<typename T>
+    requires requires (T &view) { osp::arrayView(view); }
+constexpr decltype(auto) as_2d(T &view, std::size_t rowSize) noexcept
+{
+    return ArrayView2DWrapper<decltype(osp::arrayView(view))>{ .view = osp::arrayView(view), .rowSize = rowSize };
+}
+
+/**
+ * @brief Returns an interface that treats an ArrayView as a 2D array of equally sized rows.
+ */
 template<typename T>
-constexpr ArrayView2DWrapper<T> as_2d(ArrayView<T> view, std::size_t columns) noexcept
+constexpr ArrayView2DWrapper< ArrayView<T> > as_2d(ArrayView<T> view, std::size_t rowSize) noexcept
 {
-    return { .view = view, .columns = columns };
+    return { .view = view, .rowSize = rowSize };
 }
 
 /**
- * @brief slice_2d_row
- * @param view
- * @param index
- * @param size
+ * @brief Returns an interface that treats an ArrayView as a 2D array of equally sized rows.
  */
 template<typename T>
-ArrayView<T> slice_2d_row(ArrayView<T> const& view, std::size_t index, std::size_t size) noexcept
+constexpr ArrayView2DWrapper< Corrade::Containers::StridedArrayView1D<T> >
+        as_2d(Corrade::Containers::StridedArrayView1D<T> view, std::size_t rowSize) noexcept
 {
-    return view.sliceSize(index, size);
+    return { .view = view, .rowSize = rowSize };
 }
 
 /**

src/osp/core/buffer_format.h

@@ -0,0 +1,139 @@
+/**
+ * Open Space Program
+ * Copyright © 2019-2024 Open Space Program Project
+ *
+ * MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#pragma once
+
+#include <Corrade/Containers/Array.h>
+#include <Corrade/Containers/StridedArrayView.h>
+
+namespace osp
+{
+
+/**
+ * @brief Buffer Attribute Format. Describes how to access element attribute data within a buffer.
+ *
+ * This is useful for SIMD, GPU, and serialization. A SIMD n-body simulation may prefer [XXXYYYZZZ]
+ * to store positions, but GPU mesh vertex positions prefer [XYZXYZXYZ...].
+ */
+template <typename T>
+struct BufAttribFormat
+{
+    using View_t        = Corrade::Containers::StridedArrayView1D<T>;
+    using ViewConst_t   = Corrade::Containers::StridedArrayView1D<T const>;
+    using Data_t        = Corrade::Containers::ArrayView<unsigned char>;
+    using DataConst_t   = Corrade::Containers::ArrayView<unsigned char const>;
+
+    constexpr View_t view(Data_t data, std::size_t count) const noexcept
+    {
+        return stridedArrayView<T>(data, reinterpret_cast<T*>(&data[offset]), count, stride);
+    }
+
+    constexpr ViewConst_t view_const(DataConst_t data, std::size_t count) const noexcept
+    {
+        return stridedArrayView<T const>(data, reinterpret_cast<T const*>(&data[offset]), count, stride);
+    }
+
+    constexpr bool is_not_used() const noexcept { return stride == 0; }
+
+    std::size_t     offset{};
+    std::ptrdiff_t  stride{};
+};
+
+/**
+ * @brief Builder to more easily create BufAttribFormats
+ */
+class BufferFormatBuilder
+{
+public:
+
+    /**
+     * @brief Insert a single contiguous block of attribute data
+     *
+     * To make the buffer format [XXXX... YYYYY... ZZZZZ...] for example, use:
+     *
+     * @code{.cpp}
+     * builder.insert_block<float>(count); // X
+     * builder.insert_block<float>(count); // Y
+     * builder.insert_block<float>(count); // Z
+     * @endcode
+     *
+     * @param count [in] Number of elements
+     */
+    template <typename T>
+    constexpr BufAttribFormat<T> insert_block(std::size_t const count)
+    {
+        auto const prevbytesUsed = m_totalSize;
+        m_totalSize += sizeof(T) * count;
+
+        return { .offset = prevbytesUsed, .stride = sizeof(T) };
+    }
+
+    /**
+     * @brief Insert interleved attribute data
+     *
+     * To make the buffer format [XYZXYZXYZXYZ...] for example, use:
+     *
+     * @code{.cpp}
+     * BufAttribFormat<float> attribX;
+     * BufAttribFormat<float> attribY;
+     * BufAttribFormat<float> attribZ;
+     * builder.insert_interleave(count, attribX, attribY, attribZ);
+     * @endcode
+     *
+     * @param count [in] Number of elements
+     */
+    template <typename ... T>
+    constexpr void insert_interleave(std::size_t count, BufAttribFormat<T>& ... rInterleve)
+    {
+        constexpr std::size_t stride = (sizeof(T) + ...);
+
+        (rInterleve.m_stride = ... = stride);
+
+        interleave_aux(m_totalSize, rInterleve ...);
+
+        m_totalSize += stride * count;
+    }
+
+    constexpr std::size_t total_size() const noexcept
+    {
+        return m_totalSize;
+    }
+
+private:
+
+    template <typename FIRST_T, typename ... T>
+    constexpr void interleave_aux(std::size_t const pos, BufAttribFormat<FIRST_T>& rInterleveFirst, BufAttribFormat<T>& ... rInterleve)
+    {
+        rInterleveFirst.m_offset = pos;
+
+        if constexpr (sizeof...(T) != 0)
+        {
+            interleave_aux(pos + sizeof(FIRST_T), rInterleve ...);
+        }
+    }
+
+    std::size_t m_totalSize{0};
+};
+
+} // namespace osp

src/osp/core/math_int64.h

@@ -54,25 +54,14 @@ constexpr std::uint64_t absdelta(std::int64_t lhs, std::int64_t rhs) noexcept
 /**
  * @brief (distance between a and b) > threshold
  *
- * This function is quick and dirty, max threshold is limited to 1,431,655,765
  */
-constexpr bool is_distance_near(Vector3l const a, Vector3l const b, std::uint64_t const threshold) noexcept
+constexpr bool is_distance_near(Vector3l const a, Vector3l const b, double const threshold) noexcept
 {
-    std::uint64_t const dx = absdelta(a.x(), b.x());
-    std::uint64_t const dy = absdelta(a.y(), b.y());
-    std::uint64_t const dz = absdelta(a.z(), b.z());
+    double const dx( absdelta(a.x(), b.x()) );
+    double const dy( absdelta(a.y(), b.y()) );
+    double const dz( absdelta(a.z(), b.z()) );
 
-    // 1431655765 = sqrt(2^64)/3 = max distance without risk of overflow
-    constexpr std::uint64_t dmax = 1431655765ul;
-
-    if (dx > dmax || dy > dmax || dz > dmax)
-    {
-        return false;
-    }
-
-    std::uint64_t const magnitudeSqr = (dx*dx + dy*dy + dz*dz);
-
-    return magnitudeSqr < threshold*threshold;
+    return (dx*dx + dy*dy + dz*dz) < threshold*threshold;
 }
 
 } // namespace osp