New example showcasing usage with Box2D.

CMakeLists.txt

@@ -60,6 +60,7 @@ find_package(Magnum REQUIRED)
 include(CMakeDependentOption)
 option(WITH_AREALIGHTS_EXAMPLE "Build arealights example" OFF)
 option(WITH_AUDIO_EXAMPLE "Build audio example (requires Magnum Audio library)" OFF)
+option(WITH_BOX2D_EXAMPLE "Build Box2D integration example" OFF)
 option(WITH_BULLET_EXAMPLE "Build Bullet integration example (requires BulletIntegration library)" OFF)
 cmake_dependent_option(WITH_CUBEMAP_EXAMPLE "Build CubeMap example (requires JpegImporter plugin)" OFF "NOT MAGNUM_TARGET_GLES" OFF)
 option(WITH_LEAPMOTION_EXAMPLE "Build LeapMotion example" OFF)

CREDITS.md

@@ -6,6 +6,8 @@ Third-party components
 -   The sound file used is a Chimes Sound Effect from
     http://www.orangefreesounds.com/chimes-sound-effect/, licensed under
     a [Creative Commons Attribution 4.0 International License](http://creativecommons.org/licenses/by/4.0/).
+-   The Box2D example uses the [Box2D](https://box2d.org/) library, licensed
+    under the [zlib license](https://github.com/erincatto/Box2D/blob/master/LICENSE)
 -   The sokol_gfx Triangle example uses the [sokol_gfx](https://github.com/floooh/sokol)
     library by Andre Weissflog, licensed under the
     [zlib/libpng license](https://github.com/floooh/sokol/blob/master/LICENSE).
@@ -24,6 +26,7 @@ Contributors to Magnum examples
 -   Bill Robinson ([@wivlaro](https://github.com/wivlaro) -- Shadows example
 -   Olga Turanksaya ([@olga-python](https://github.com/olga-python)) -- Gentoo
     ebuild
+-   Michal Mikula -- Box2D example
 -   Nathan Ollerenshaw ([@matjam](https://github.com/matjam)) --- Ubuntu
     package updates, a PPA repository for stable versions
 

modules/FindBox2D.cmake

@@ -0,0 +1,62 @@
+#.rst:
+# Find Box2D
+# ----------
+#
+# Finds the Box2D library. This module defines:
+#
+#  Box2D_FOUND          - True if Box2D library is found
+#  Box2D::Box2D         - Box2D imported target
+#
+# Additionally these variables are defined for internal usage:
+#
+#  BOX2D_LIBRARY        - Box2D library
+#  BOX2D_INCLUDE_DIR    - Include dir
+#
+
+#
+#   This file is part of Magnum.
+#
+#   Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018
+#             Vladimír Vondruš <mosra@centrum.cz>
+#
+#   Permission is hereby granted, free of charge, to any person obtaining a
+#   copy of this software and associated documentation files (the "Software"),
+#   to deal in the Software without restriction, including without limitation
+#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
+#   and/or sell copies of the Software, and to permit persons to whom the
+#   Software is furnished to do so, subject to the following conditions:
+#
+#   The above copyright notice and this permission notice shall be included
+#   in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+#   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+#   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+#   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+#   DEALINGS IN THE SOFTWARE.
+#
+
+# Library
+find_library(BOX2D_LIBRARY NAMES Box2D)
+
+# Include dir
+find_path(BOX2D_INCLUDE_DIR
+    NAMES Box2D/Box2D.h)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Box2D DEFAULT_MSG
+    BOX2D_LIBRARY
+    BOX2D_INCLUDE_DIR)
+
+mark_as_advanced(FORCE
+    BOX2D_LIBRARY
+    BOX2D_INCLUDE_DIR)
+
+if(NOT TARGET Box2D::Box2D)
+    add_library(Box2D::Box2D UNKNOWN IMPORTED)
+    set_target_properties(Box2D::Box2D PROPERTIES
+        IMPORTED_LOCATION ${BOX2D_LIBRARY}
+        INTERFACE_INCLUDE_DIRECTORIES ${BOX2D_INCLUDE_DIR})
+endif()

src/CMakeLists.txt

@@ -46,6 +46,10 @@ if(WITH_AUDIO_EXAMPLE)
     add_subdirectory(audio)
 endif()
 
+if(WITH_BOX2D_EXAMPLE)
+    add_subdirectory(box2d)
+endif()
+
 if(WITH_BULLET_EXAMPLE)
     add_subdirectory(bullet)
 endif()

src/box2d/Box2DExample.cpp

@@ -0,0 +1,176 @@
+/*
+    This file is part of Magnum.
+
+    Original authors — credit is appreciated but not required:
+
+        2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 —
+            Vladimír Vondruš <mosra@centrum.cz>
+        2018 — Michal Mikula <miso.mikula@gmail.com>
+
+    This is free and unencumbered software released into the public domain.
+
+    Anyone is free to copy, modify, publish, use, compile, sell, or distribute
+    this software, either in source code form or as a compiled binary, for any
+    purpose, commercial or non-commercial, and by any means.
+
+    In jurisdictions that recognize copyright laws, the author or authors of
+    this software dedicate any and all copyright interest in the software to
+    the public domain. We make this dedication for the benefit of the public
+    at large and to the detriment of our heirs and successors. We intend this
+    dedication to be an overt act of relinquishment in perpetuity of all
+    present and future rights to this software under copyright law.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include <Box2D/Box2D.h>
+#include <Magnum/GL/Context.h>
+#include <Magnum/GL/DefaultFramebuffer.h>
+#include <Magnum/GL/Buffer.h>
+#include <Magnum/GL/Mesh.h>
+#include <Magnum/MeshTools/Compile.h>
+#include <Magnum/Platform/Sdl2Application.h>
+#include <Magnum/Primitives/Square.h>
+#include <Magnum/SceneGraph/Camera.h>
+#include <Magnum/SceneGraph/Drawable.h>
+#include <Magnum/SceneGraph/TranslationRotationScalingTransformation2D.h>
+#include <Magnum/SceneGraph/Scene.h>
+#include <Magnum/Shaders/Flat.h>
+#include <Magnum/Trade/MeshData2D.h>
+
+namespace Magnum { namespace Examples {
+
+typedef SceneGraph::Object<SceneGraph::TranslationRotationScalingTransformation2D> Object2D;
+typedef SceneGraph::Scene<SceneGraph::TranslationRotationScalingTransformation2D> Scene2D;
+
+using namespace Math::Literals;
+
+class Box2DExample: public Platform::Application {
+    public:
+        explicit Box2DExample(const Arguments& arguments);
+
+    private:
+        void drawEvent() override;
+        void mousePressEvent(MouseEvent& event) override;
+
+        b2Body* createBody(Object2D& object, const Vector2& size, b2BodyType type, const Vector2& position, Float density = 1.0f);
+
+        GL::Mesh _mesh;
+        Shaders::Flat2D _shader;
+
+        Scene2D _scene;
+        Object2D* _cameraObject;
+        SceneGraph::Camera2D* _camera;
+        SceneGraph::DrawableGroup2D _drawables;
+        Containers::Optional<b2World> _world;
+};
+
+class BoxDrawable: public SceneGraph::Drawable2D {
+    public:
+        explicit BoxDrawable(Object2D& object, GL::Mesh& mesh, Shaders::Flat2D& shader, const Color4& color, SceneGraph::DrawableGroup2D& drawables): SceneGraph::Drawable2D{object, &drawables}, _mesh(mesh), _shader(shader), _color{color} {}
+
+    private:
+        void draw(const Matrix3& transformationMatrix, SceneGraph::Camera2D& camera) override {
+            _shader
+                .setTransformationProjectionMatrix(camera.projectionMatrix()*transformationMatrix)
+                .setColor(_color);
+            _mesh.draw(_shader);
+        }
+
+        GL::Mesh& _mesh;
+        Shaders::Flat2D& _shader;
+        Color4 _color;
+};
+
+b2Body* Box2DExample::createBody(Object2D& object, const Vector2& halfSize, const b2BodyType type, const Vector2& position, const Float density) {
+    b2BodyDef bodyDefinition;
+    bodyDefinition.position.Set(position.x(), position.y());
+    bodyDefinition.type = type;
+    b2Body* body = _world->CreateBody(&bodyDefinition);
+
+    b2PolygonShape shape;
+    shape.SetAsBox(halfSize.x(), halfSize.y());
+
+    b2FixtureDef fixture;
+    fixture.friction = 0.8f;
+    fixture.density = density;
+    fixture.shape = &shape;
+    body->CreateFixture(&fixture);
+
+    body->SetUserData(&object);
+    object.setScaling(halfSize);
+
+    return body;
+}
+
+Box2DExample::Box2DExample(const Arguments& arguments):
+    Platform::Application{arguments, Configuration{}.setTitle("Magnum Box2D Example")}
+{
+    /* Configure camera */
+    _cameraObject = new Object2D{&_scene};
+    _camera = new SceneGraph::Camera2D{*_cameraObject};
+    _camera->setAspectRatioPolicy(SceneGraph::AspectRatioPolicy::Extend)
+        .setProjectionMatrix(Matrix3::projection({20.0f, 20.0f}))
+        .setViewport(GL::defaultFramebuffer.viewport().size());
+
+    /* Create the Box2D world with the usual gravity vector */
+    _world.emplace(b2Vec2{0.0f, -9.81f});
+
+    /* Create the box mesh */
+    _mesh = MeshTools::compile(Primitives::squareSolid());
+
+    /* Create the ground */
+    auto ground = new Object2D{&_scene};
+    createBody(*ground, {11.0f, 0.5f}, b2_staticBody, Vector2::yAxis(-8.0f));
+    new BoxDrawable{*ground, _mesh, _shader, 0xa5c9ea_rgbf, _drawables};
+
+    /* Create a pyramid of boxes */
+    for(std::size_t row = 0; row != 15; ++row) {
+        for(std::size_t item = 0; item != 15 - row; ++item) {
+            auto box = new Object2D{&_scene};
+            createBody(*box, {0.5f, 0.5f}, b2_dynamicBody,
+                {Float(row)*0.6f + Float(item)*1.2f - 8.5f, Float(row)*1.0f - 6.0f});
+            new BoxDrawable{*box, _mesh, _shader, 0x2f83cc_rgbf, _drawables};
+        }
+    }
+
+    setSwapInterval(1);
+    #if !defined(CORRADE_TARGET_EMSCRIPTEN) && !defined(CORRADE_TARGET_ANDROID)
+    setMinimalLoopPeriod(16);
+    #endif
+}
+
+void Box2DExample::mousePressEvent(MouseEvent& event) {
+    /* Calculate mouse position in the Box2D world. Make it relative to window,
+       with origin at center and then scale to world size with Y inverted. */
+    const auto position = _camera->projectionSize()*Vector2::yScale(-1.0f)*(Vector2{event.position()}/Vector2{windowSize()} - Vector2{0.5f});
+
+    auto destroyer = new Object2D{&_scene};
+    createBody(*destroyer, {0.5f, 0.5f}, b2_dynamicBody, position, 2.0f);
+    new BoxDrawable{*destroyer, _mesh, _shader, 0xffff66_rgbf, _drawables};
+}
+
+void Box2DExample::drawEvent() {
+    GL::defaultFramebuffer.clear(GL::FramebufferClear::Color);
+
+    /* Step the world and update all object positions */
+    _world->Step(1.0f/60.0f, 6, 2);
+    for(b2Body* body = _world->GetBodyList(); body; body = body->GetNext())
+        (*static_cast<Object2D*>(body->GetUserData()))
+            .setTranslation({body->GetPosition().x, body->GetPosition().y})
+            .setRotation(Complex::rotation(Rad(body->GetAngle())));
+
+    _camera->draw(_drawables);
+
+    swapBuffers();
+    redraw();
+}
+
+}}
+
+MAGNUM_APPLICATION_MAIN(Magnum::Examples::Box2DExample)

src/box2d/CMakeLists.txt

@@ -0,0 +1,82 @@
+#
+#   This file is part of Magnum.
+#
+#   Original authors — credit is appreciated but not required:
+#
+#       2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018 —
+#           Vladimír Vondruš <mosra@centrum.cz>
+#       2018 — Michal Mikula <miso.mikula@gmail.com>
+#
+#   This is free and unencumbered software released into the public domain.
+#
+#   Anyone is free to copy, modify, publish, use, compile, sell, or distribute
+#   this software, either in source code form or as a compiled binary, for any
+#   purpose, commercial or non-commercial, and by any means.
+#
+#   In jurisdictions that recognize copyright laws, the author or authors of
+#   this software dedicate any and all copyright interest in the software to
+#   the public domain. We make this dedication for the benefit of the public
+#   at large and to the detriment of our heirs and successors. We intend this
+#   dedication to be an overt act of relinquishment in perpetuity of all
+#   present and future rights to this software under copyright law.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+#   THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+#   IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+#   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+
+cmake_minimum_required(VERSION 2.8.12)
+
+# CMake policies. 0025 needs to be before project(), so putting all there.
+# Use AppleClang instead of Clang on Apple
+if(POLICY CMP0025)
+    cmake_policy(SET CMP0025 NEW)
+endif()
+# Don't treat imported targets with :: as files
+if(POLICY CMP0028)
+    cmake_policy(SET CMP0028 NEW)
+endif()
+# Enable MACOSX_RPATH by default
+if(POLICY CMP0042)
+    cmake_policy(SET CMP0042 NEW)
+endif()
+# Quoted variables should not be dereferenced
+if(POLICY CMP0054)
+    cmake_policy(SET CMP0054 NEW)
+endif()
+
+project(MagnumBox2DExample)
+
+# Add module path in case this is project root
+if(PROJECT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+    set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/../../modules/")
+endif()
+
+find_package(Magnum REQUIRED
+    GL
+    MeshTools
+    Primitives
+    SceneGraph
+    Sdl2Application
+    Shaders
+    Trade)
+find_package(Box2D REQUIRED)
+
+set_directory_properties(PROPERTIES CORRADE_USE_PEDANTIC_FLAGS ON)
+
+add_executable(magnum-box2d Box2DExample.cpp)
+target_link_libraries(magnum-box2d PRIVATE
+    Magnum::Application
+    Magnum::GL
+    Magnum::Magnum
+    Magnum::MeshTools
+    Magnum::Primitives
+    Magnum::SceneGraph
+    Magnum::Shaders
+    Magnum::Trade
+    Box2D::Box2D)
+
+install(TARGETS magnum-box2d DESTINATION ${MAGNUM_BINARY_INSTALL_DIR})