1 files changed, 59 insertions, 0 deletions
diff --git a/src/ground-atlas.cpp b/src/ground-atlas.cpp
new file mode 100644
index 00000000..a64264ff
--- /dev/null
+++ b/src/ground-atlas.cpp
@@ -0,0 +1,59 @@
+#include "ground-atlas.hpp"
+#include "quads.hpp"
+#include "compat/assert.hpp"
+#include "tile-image.hpp"
+#include "compat/exception.hpp"
+#include <limits>
+#include <Magnum/Math/Color.h>
+#include <Magnum/ImageView.h>
+#include <Magnum/GL/TextureFormat.h>
+
+namespace floormat {
+
+using namespace floormat::Quads;
+
+ground_atlas::ground_atlas(StringView path, StringView name, const ImageView2D& image, Vector2ub tile_count, enum pass_mode p) :
+    texcoords_{make_texcoords_array(Vector2ui(image.size()), tile_count)},
+    path_{path}, name_{name}, size_{image.size()}, dims_{tile_count}, passability{p}
+{
+    constexpr auto variant_max = std::numeric_limits<variant_t>::max();
+    fm_soft_assert(num_tiles() <= variant_max);
+    fm_soft_assert(dims_[0] > 0 && dims_[1] > 0);
+    fm_soft_assert(size_ % Vector2ui{tile_count} == Vector2ui());
+    tex_.setLabel(path_)
+        .setWrapping(GL::SamplerWrapping::ClampToEdge)
+        .setMagnificationFilter(GL::SamplerFilter::Nearest)
+        .setMinificationFilter(GL::SamplerFilter::Linear)
+        .setMaxAnisotropy(1)
+        .setBorderColor(Color4{1, 0, 0, 1})
+        .setStorage(1, GL::textureFormat(image.format()), image.size())
+        .setSubImage(0, {}, image);
+}
+
+std::array<Vector2, 4> ground_atlas::texcoords_for_id(size_t i) const
+{
+    fm_assert(i < num_tiles());
+    return texcoords_[i];
+}
+
+auto ground_atlas::make_texcoords(Vector2ui pixel_size, Vector2ub tile_count, size_t i) -> texcoords
+{
+    const auto sz = pixel_size/Vector2ui{tile_count};
+    const auto id = Vector2ui{ uint32_t(i % tile_count[0]), uint32_t(i / tile_count[0]) };
+    const auto p0 = id * sz;
+    return texcoords_at(p0, sz, pixel_size);
+}
+
+auto ground_atlas::make_texcoords_array(Vector2ui pixel_size, Vector2ub tile_count) -> std::unique_ptr<const texcoords[]>
+{
+    const size_t N = Vector2ui{tile_count}.product();
+    auto ptr = std::make_unique<std::array<Vector2, 4>[]>(N);
+    for (auto i = 0uz; i < N; i++)
+        ptr[i] = make_texcoords(pixel_size, tile_count, i);
+    return ptr;
+}
+
+size_t ground_atlas::num_tiles() const { return Vector2ui{dims_}.product(); }
+enum pass_mode ground_atlas::pass_mode() const { return passability; }
+
+} // namespace floormat