Properly link flecs library

engine/libs/flecs/examples/build/bazel/BUILD

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+package(default_visibility = ["//visibility:public"])
+
+cc_binary(
+    name = "example",
+    srcs = ["main.cpp"],
+    deps = ["@flecs//:flecs"]
+)

engine/libs/flecs/examples/build/bazel/README.md

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+You can include the flecs repository in your `WORKSPACE` with:
+
+```bazel
+git_repository(
+    name = "flecs",
+    remote = "https://github.com/SanderMertens/flecs",
+    commit = "f150d96ba9ea8be2b24dbf2217368c231cb17720", # v2.3.2+merge329
+    shallow_since = "1615075784 -0800",
+)
+```
+
+And then add it to your `BUILD` with:
+
+```bazel
+    deps = ["@flecs//:flecs"]
+```
+
+This directory contains a complete example of this usage. To try it you can run the following from your terminal:
+
+```
+bazel run example
+```

engine/libs/flecs/examples/build/bazel/WORKSPACE

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+load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
+
+git_repository(
+    name = "flecs",
+    remote = "https://github.com/SanderMertens/flecs",
+    commit = "f150d96ba9ea8be2b24dbf2217368c231cb17720", # v2.3.2+merge329
+    shallow_since = "1615075784 -0800",
+)

engine/libs/flecs/examples/build/bazel/main.cpp

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+#include "flecs.h"
+#include <iostream>
+
+/* Component types */
+struct Position {
+    double x, y;
+};
+
+struct Velocity {
+    double x, y;
+};
+
+int main(int argc, char *argv[]) {
+    flecs::world world(argc, argv);
+
+    flecs::component<Position>(world, "Position");
+    flecs::component<Velocity>(world, "Velocity");
+
+    flecs::system<Position, const Velocity>(world)
+        .iter([](const flecs::iter& it, 
+            Position *p, 
+            const Velocity *v) 
+        {    
+            for (auto row : it) {
+                p[row].x += v[row].x;
+                p[row].y += v[row].y;
+
+                std::cout << "Moved " << it.entity(row).name() << " to {" <<
+                    p[row].x << ", " << p[row].y << "}" << std::endl;
+            }
+        });
+
+    flecs::entity(world, "MyEntity")
+        .set<Position>({0, 0})
+        .set<Velocity>({1, 1});
+
+    world.set_target_fps(1);
+
+    std::cout << "Application move_system is running, press CTRL-C to exit..." << std::endl;
+
+    /* Run systems */
+    while (world.progress()) { }
+}

engine/libs/flecs/examples/build/cmake/CMakeLists.txt

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+cmake_minimum_required (VERSION 2.8.7)
+
+project (cmake_example)
+
+set(CMAKE_CXX_STANDARD 11)
+
+add_subdirectory (flecs)
+
+add_executable(cmake_example main.cpp)
+add_executable(cmake_example_static main.cpp)
+
+target_link_libraries(cmake_example flecs)
+target_link_libraries(cmake_example_static flecs_static)

engine/libs/flecs/examples/build/cmake/README.md

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+For this to work, flecs needs to be a subdirectory of the example.

engine/libs/flecs/examples/build/cmake/main.cpp

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+#include "flecs.h"
+#include <iostream>
+
+/* Component types */
+struct Position {
+    double x, y;
+};
+
+struct Velocity {
+    double x, y;
+};
+
+int main(int argc, char *argv[]) {
+    flecs::world ecs(argc, argv);
+
+    ecs.system<Position, const Velocity>()
+        .iter([](const flecs::iter& it, 
+            Position *p, 
+            const Velocity *v) 
+        {    
+            for (auto row : it) {
+                p[row].x += v[row].x;
+                p[row].y += v[row].y;
+
+                std::cout << "Moved " << it.entity(row).name() << " to {" <<
+                    p[row].x << ", " << p[row].y << "}" << std::endl;
+            }
+        });
+
+    ecs.entity("MyEntity")
+        .set<Position>({0, 0})
+        .set<Velocity>({1, 1});
+
+    ecs.set_target_fps(1);
+
+    std::cout << "Application move_system is running, press CTRL-C to exit..." << std::endl;
+
+    /* Run systems */
+    while (ecs.progress()) { }
+}