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inc/lvgl/src/libs/gltf/math/lv_gltf_math.cpp

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+/**
+ * @file lv_gltf_math.cpp
+ *
+ */
+
+/*********************
+ *      INCLUDES
+ *********************/
+
+#include "lv_gltf_math.hpp"
+
+#if LV_USE_GLTF
+
+#include <fastgltf/math.hpp>
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ *  STATIC PROTOTYPES
+ **********************/
+
+/**********************
+ *  STATIC VARIABLES
+ **********************/
+
+/**********************
+ *      MACROS
+ **********************/
+
+/**********************
+ *   GLOBAL FUNCTIONS
+ **********************/
+
+/** Creates a right-handed view matrix */
+fastgltf::math::fmat4x4 lv_gltf_math_look_at_rh(const fastgltf::math::fvec3 & eye, const fastgltf::math::fvec3 & center,
+                                                const fastgltf::math::fvec3 & up) noexcept
+{
+    auto dir = normalize(center - eye);
+    auto lft = normalize(cross(dir, up));
+    auto rup = cross(lft, dir);
+
+    fastgltf::math::fmat4x4 ret(1.f);
+    ret.col(0) = { lft.x(), rup.x(), -dir.x(), 0.f };
+    ret.col(1) = { lft.y(), rup.y(), -dir.y(), 0.f };
+    ret.col(2) = { lft.z(), rup.z(), -dir.z(), 0.f };
+    ret.col(3) = { -dot(lft, eye), -dot(rup, eye), dot(dir, eye), 1.f };
+    return ret;
+}
+
+/**
+ * Creates a right-handed perspective matrix, with the near and far clips at -1 and +1, respectively.
+ * @param fov The FOV in radians
+ */
+[[nodiscard]] fastgltf::math::fmat4x4 lv_gltf_math_perspective_rh(float fov, float ratio, float z_near,
+                                                                  float z_far) noexcept
+{
+    fastgltf::math::fmat4x4 ret(0.f);
+    auto tanHalfFov = std::tan(fov / 2.f);
+    ret.col(0).x() = 1.f / (ratio * tanHalfFov);
+    ret.col(1).y() = 1.f / tanHalfFov;
+    ret.col(2).z() = -(z_far + z_near) / (z_far - z_near);
+    ret.col(2).w() = -1.f;
+    ret.col(3).z() = -(2.f * z_far * z_near) / (z_far - z_near);
+    return ret;
+}
+
+
+/**********************
+ *   STATIC FUNCTIONS
+ **********************/
+
+#endif /*LV_USE_GLTF*/