1 files changed, 39 insertions, 0 deletions
diff --git a/src/tile-atlas.cpp b/src/tile-atlas.cpp
new file mode 100644
index 00000000..d5d56cce
--- /dev/null
+++ b/src/tile-atlas.cpp
@@ -0,0 +1,39 @@
+#include "tile-atlas.hpp"
+#include <Corrade/Containers/StringView.h>
+#include <Magnum/ImageView.h>
+#include <Magnum/GL/TextureFormat.h>
+
+namespace Magnum::Examples {
+
+tile_atlas::tile_atlas(Containers::StringView name, const ImageView2D& image, Vector2ui dims) :
+    name_{name},
+    size_{image.size()},
+    dims_{dims}
+{
+    CORRADE_INTERNAL_ASSERT(dims_[0] > 0 && dims_[1] > 0);
+    CORRADE_INTERNAL_ASSERT(size_ % dims_ == Vector2ui{});
+    CORRADE_INTERNAL_ASSERT(dims_.product() < 256);
+    tex_.setWrapping(GL::SamplerWrapping::ClampToBorder)
+        .setMagnificationFilter(GL::SamplerFilter::Linear)
+        .setMinificationFilter(GL::SamplerFilter::Linear)
+        .setMaxAnisotropy(0)
+        .setStorage(GL::textureFormat(image.format()), image.size())
+        .setSubImage({}, image);
+}
+
+std::array<Vector2, 4> tile_atlas::texcoords_for_id(std::size_t id_) const
+{
+    const auto sz = size_/dims_;
+    ASSERT(id_ < sz.product());
+    const Vector2ui id = { (unsigned)id_ % dims_[0], (unsigned)id_ / dims_[0] };
+    const Vector2 p0(id * sz), p1(sz);
+    const auto x0 = p0.x(), x1 = p1.x(), y0 = p0.y(), y1 = p1.y();
+    return {{
+        { x0+x1, y0+y1 }, // bottom right
+        { x0+x1, y0    }, // top right
+        { x0,    y0+y1 }, // bottom left
+        { x0,    y0    }  // top left
+    }};
+}
+
+} // namespace Magnum::Examples