1 files changed, 59 insertions, 0 deletions
diff --git a/atlas.cpp b/atlas.cpp
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index 00000000..46153629
--- /dev/null
+++ b/atlas.cpp
@@ -0,0 +1,59 @@
+#include "atlas.hpp"
+#include <Magnum/ImageView.h>
+#include <Magnum/GL/TextureFormat.h>
+
+namespace Magnum::Examples {
+
+atlas_texture::atlas_texture(const Trade::ImageData2D& image, Vector2i dims) :
+    size_{image.size()},
+    dims_{dims},
+    tile_size_{size_ / dims}
+{
+    CORRADE_INTERNAL_ASSERT(dims_[0] > 0 && dims_[1] > 0);
+    CORRADE_INTERNAL_ASSERT(tile_size_ * dims_ == size_);
+    CORRADE_INTERNAL_ASSERT(size_ % dims_ == Vector2i{});
+    tex_.setWrapping(GL::SamplerWrapping::ClampToEdge)
+        .setMagnificationFilter(GL::SamplerFilter::Nearest)
+        .setMinificationFilter(GL::SamplerFilter::Linear)
+        .setStorage(1, GL::textureFormat(image.format()), image.size())
+        .setSubImage(0, {}, image);
+}
+
+std::array<Vector2, 4> atlas_texture::texcoords_for_id(int id_) const
+{
+    CORRADE_INTERNAL_ASSERT(id_ >= 0 && id_ < dims_.product());
+    constexpr Vector2 _05 = { 0.5f, 0.5f };
+    constexpr Vector2i _1 = { 1, 1 };
+    Vector2i id = { id_ % dims_[1], id_ / dims_[1] };
+    auto p0 = (Vector2(id * tile_size_) + _05) / Vector2(size_);
+    auto p1 = (Vector2((id + _1) * tile_size_) + _05) / Vector2(size_);
+    return {{
+        { p1[0], p1[1] }, // bottom right
+        { p1[0], p0[1] }, // top right
+        { p0[0], p1[1] }, // bottom left
+        { p0[0], p0[1] }  // top left
+    }};
+}
+
+std::array<Vector3, 4> atlas_texture::floor_quad(Vector3 center, Vector2 size)
+{
+    float x = size[0]*.5f, y = size[1]*.5f;
+    return {{
+        { x + center[0], -y + center[1], 0},
+        { x + center[0],  y + center[1], 0},
+        {-x + center[0], -y + center[1], 0},
+        {-x + center[0],  y + center[1], 0},
+    }};
+}
+
+std::array<UnsignedShort, 6> atlas_texture::indices(int N)
+{
+    CORRADE_INTERNAL_ASSERT(N >= 0);
+    using u16 = UnsignedShort;
+    return {                                        /* 3--1 1 */
+        (u16)(0+N*4), (u16)(1+N*4), (u16)(2+N*4),   /* | / /| */
+        (u16)(2+N*4), (u16)(1+N*4), (u16)(3+N*4),   /* |/ / | */
+    };                                              /* 2 2--0 */
+}
+
+} // namespace Magnum::Examples