8. Making It in Time
<< RETURN TO THE PREVIOUS SECTION
As the frame rate of our application may vary (i.e. the AppWorldLogic::update() method will be called more or less frequently) depending on hardware, we should do something to ensure that certain actions are performed at the same time periods regardless of the frame rate (e.g. change something once per second etc). To make your game frame rate independent you can use the a scaling multiplier (the time in seconds it took to complete the last frame) returned by the following methods:
- App::getIfps() returns the inverse FPS value for your application.
- Game::getIfps() returns the scaled inverse FPS value. This class is to be used when you want to speed up, slow down or pause rendering, physics or game logic.
To scale your transformations you can use the following code:
#include <core/unigine.h>
/* .. */
int update() {
// getting an inverse FPS value (the time in seconds it took to complete the last frame)
float ifps = engine.game.getIFps();
// moving the node up by 0.3 units every second instead of every frame
node.worldTranslate(Vec3(0.0f, 0.0f, 0.3f * ifps));
return 1;
}
To perform some changes once in a certain period of time you can use the following code:
#include <core/unigine.h>
float INTERVAL_DURATION = 5;
float elapsed_time = INTERVAL_DURATION;
/* .. */
int update() {
// getting an inverse FPS value (the time in seconds it took to complete the last frame)
float ifps = engine.game.getIFps();
// checking if it's time to make changes
if (elapsed_time < 0.0f)
{
/* .. DO SOME CHANGES .. */
// resetting elapsed time counter
elapsed_time = INTERVAL_DURATION;
}
// decreasing elapsed time counter
elapsed_time -= ifps;
return 1;
}
Additional information:
- For more information on the Game class, see the Game class article.
- For more information on the App class, see the App class article.
Project Progress#
In our project we are going to change the position of the sun and make some transformations to our initial set of objects every frame. As you already know, everything related to modification of nodes (moving, changing materials and parameters etc.) as well as other graphics-related functions to be called every frame should be placed in the AppWorldLogic::update() method. So, let us write methods called updateLights and updateObjects and place them to where they should be.
In the AppWorldLogic.h file, we define the duration of the time interval after which we are going to change the scale and direction of the forward vector for our objects, an auxiliary variable for the update cycle called elapsed_time and declare our updateLights and updateObjects methods.
// AppWorldLogic.h
/* .. */
const float CHANGE_INTERVAL = 1; // the interval between changes of objects' parameters, in seconds
const float SUN_ROTATION_RATE = 10.0f; // rotation rate of the sun
/* .. */
class AppWorldLogic : public Unigine::WorldLogic {
public:
/* .. */
private:
/* .. */
// updating lights
int updateLights(float ifps);
// updating objects
int updateObjects(float ifps);
/* .. */
float elapsed_time = CHANGE_INTERVAL; // current time left to change current scale of our objects
float sun_angle = 0.0f; // current sun position
/* .. */
};
In the AppWorldLogic.cpp file let us implement our updateObjects and updateLights methods and insert them into the AppWorldLogic::update() method. In the updateObjects method we are going to use the method from the previous section called transformNode. There is one more thing we should do: to initialize pseudo-random number generator in the AppWorldLogic::init() method.
// AppWorldLogic.cpp
/* .. */
/// method updating positions of lights
int AppWorldLogic::updateLights(float ifps)
{
// updating the Sun rotation angle
sun_angle += SUN_ROTATION_RATE * ifps;
if (sun_angle > 360.0f) sun_angle = 0.0f;
// changing the Sun position using the new angle
thesun->setWorldRotation(Math::quat(Math::vec3(0.5f, 0.0f, 0.5f), 180.0f - sun_angle));
return 1;
}
/// method updating the initial set of scene objects
int AppWorldLogic::updateObjects(float ifps)
{
ObjectMeshDynamicPtr obj;
// changing transformation for all scene objects named "my_meshdynamic_*" (initial set)
for (auto it = Objects.begin(); it != Objects.end(); it++)
{
obj = it.get();
if (strstr(obj->getName(), "my_meshdynamic_"))
{
// transform the node
transformNode(obj, ifps);
}
}
return 1;
}
/* .. */
int AppWorldLogic::init()
{
/* .. */
// initializing pseudo-random number generator
Game::setSeed(time(NULL));
/* .. */
}
/* .. */
int AppWorldLogic::update()
{
// getting an inverse FPS value (the time in seconds it took to complete the last frame)
float ifps = Game::getIFps();
// checking if it's time to change current scale and forward vector direction of our objects
if (elapsed_time < 0.0f)
{
// change current scaling vector for objects
current_objects_scale = Math::vec3(Game::getRandomFloat(0.8f, 1.2f));
// change forward direction for objects
forward_direction = forward_direction * Math::rotateZ(60.0f);
// resetting elapsed time counter
elapsed_time = CHANGE_INTERVAL;
}
// decreasing the time counter to the next change of current scale and forward vector direction
elapsed_time -= ifps;
// updating objects
updateObjects(ifps);
// updating lights
updateLights(ifps);
return 1;
}
/* .. */
Source Files
You can copy the code below and paste it to the corresponding source files of your project:
AppWorldLogic.h
#ifndef __APP_WORLD_LOGIC_H__
#define __APP_WORLD_LOGIC_H__
#include <UnigineLogic.h>
#include <UnigineStreams.h>
#include <UnigineObjects.h>
#include <UnigineGame.h>
#include <UnigineLights.h>
#include <UnigineMaterials.h>
#include <UnigineWorld.h>
using namespace Unigine;
// auxiliary constants
const float DELTA_ANGLE = 60.0f; // delta angle of objects rotation
const float MOVING_SPEED = 3.0f; // speed of objects movement
const float CHANGE_INTERVAL = 1.0f; // the interval between changes of objects' parameters, in seconds
const float SUN_ROTATION_RATE = 10.0f; // rotation rate of the sun
class AppWorldLogic : public WorldLogic {
public:
AppWorldLogic();
virtual ~AppWorldLogic();
virtual int init();
virtual int update();
virtual int postUpdate();
virtual int updatePhysics();
virtual int shutdown();
virtual int save(const StreamPtr &stream);
virtual int restore(const StreamPtr &stream);
private:
PlayerSpectatorPtr player;
// pointers to light sources
LightWorldPtr thesun;
LightOmniPtr light_omni;
LightProjPtr projector;
// auxiliary functions
int addMeshToScene(const char *file_name, const char *mesh_name, const char *material_name, Math::Vec3 position);
int removeMeshFromScene(const char *node_name);
int transformNode(NodePtr node);
// initialization functions
int initObjects();
int initPlayer();
int initLights();
int initMaterials();
// update functions
int updateLights();
int updateObjects();
// shutdown functions
int clearMaterials();
int removeObjects();
// scene objects vector
Vector <ObjectMeshDynamicPtr> Objects;
Math::vec3 current_objects_scale = Math::vec3(1.0f); // current scaling vector for objects
Math::Vec3 forward_direction = Math::Vec3(0.0f, -1.0f, 0.0f); // current forward direction vector for objects
float elapsed_time = CHANGE_INTERVAL; // current time left to change current scale and forward direction of our objects
float sun_angle = 0.0f; // current sun position
};
#endif // __APP_WORLD_LOGIC_H__
AppWorldLogic.cpp
#include "AppWorldLogic.h"
// World logic, it takes effect only when the world is loaded.
// These methods are called right after corresponding world script's (UnigineScript) methods.
//-----------------------------------------------------------------------------------------------------------------------------
//---------------------------------------------- AUXILIARY FUNCTIONS AND METHODS ----------------------------------------------
//-----------------------------------------------------------------------------------------------------------------------------
float ifps;
/// method adding a Dynamic Mesh Object to the scene. If an empty filename is passed the method creates a default box; otherwise, loads a mesh-file with a given name.
int AppWorldLogic::addMeshToScene(const char *file_name, const char *mesh_name, const char *material_name, Math::Vec3 position)
{
MeshPtr mesh = Mesh::create();
ObjectMeshDynamicPtr omd;
if (file_name) { // loading a mesh from a specified file
if (!mesh->load(file_name))
{
Log::error("\nError opening .mesh file!\n");
mesh.clear();
return 0;
}
else omd = ObjectMeshDynamic::create(mesh);
}
else // creating a default box
{
mesh->addBoxSurface("box_surface", Math::vec3(0.5f));
omd = ObjectMeshDynamic::create(mesh);
}
// setting node material, name and position
omd->setMaterial(material_name, "*");
omd->setName(mesh_name);
omd->setWorldPosition(position);
// updating the list of scene objects
Objects.append(omd);
// reporting progress to the console
Log::message("-> Object %s added to the scene.\n", mesh_name);
// clearing the mesh
mesh.clear();
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method deleting a Dynamic Mesh Object with a given name from the scene
int AppWorldLogic::removeMeshFromScene(const char *node_name)
{
// getting a pointer to the node with a given name and downcasting it to ObjectMeshDynamicPtr
ObjectMeshDynamicPtr object = checked_ptr_cast<ObjectMeshDynamic>(World::getNodeByName(node_name));
if (object)
{
// reporting node deletion to the console
Log::message("Removing %s node named %s from the scene.\n", object->getTypeName(), node_name);
// removing the node with a given name from the list of scene objects
for (int i = 0; i < Objects.size(); i++)
{
if (strcmp(Objects[i]->getName(), node_name) == 0) {
Objects.remove(i);
break;
}
}
// removing the node from the scene
object->deleteLater();
return 1;
}
return 0;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method performing node transformations
int AppWorldLogic::transformNode(NodePtr node)
{
// getting current node transformation matrix
Math::Mat4 transform = node->getTransform();
// calculating delta rotation around an arbitrary axis
Math::quat delta_rotation = Math::quat(rand() % 2, rand() % 2, rand() % 2, DELTA_ANGLE * ifps);
// setting node's scale, rotation and position
node->setWorldScale(current_objects_scale);
node->setWorldRotation(node->getWorldRotation() * delta_rotation);
node->setWorldPosition(node->getWorldPosition() + forward_direction * MOVING_SPEED * ifps);
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
//---------------------------------------------- INITIALIZATION METHODS -------------------------------------------------------
//-----------------------------------------------------------------------------------------------------------------------------
/// method performing initialization of the set of 4 boxes
int AppWorldLogic::initObjects()
{
int index = 0;
for (int x = 0; x < 2; x++)
{
for (int y = 0; y < 2; y++)
{
addMeshToScene(NULL, String::format("my_meshdynamic_%d", index), String::format("my_mesh_base%d", index), Math::Vec3(x, y, 1.0f));
index++;
}
}
// reporting progress to the console
Log::warning("Objects generation OK!\n\n");
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method performing initialization of the player
int AppWorldLogic::initPlayer()
{
// creating a new PlayerSpectator instance
player = PlayerSpectator::create();
// setting player's FOV, ZNear, ZFar
player->setFov(90.0f);
player->setZNear(0.1f);
player->setZFar(10000.0f);
// setting player's view direction vector and position
player->setPosition(Math::Vec3(3.0f));
player->setDirection(Math::vec3(-1.0f), Math::vec3(0.0f, 0.0f, -1.0f));
// setting the player as a default one via the Game singleton instance
Game::setPlayer(player);
//reporting progress to the console
Log::warning("\nPlayer initialization OK!\n\n");
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method performing initialization of lights
int AppWorldLogic::initLights()
{
// creating an omni light and setting up its parameters
light_omni = LightOmni::create(Math::vec4(1.0f, 1.0f, 1.0f, 1.0f), 10.0f, "");
light_omni->setWorldPosition(Math::Vec3(0.0f, 0.0f, 5.0f));
light_omni->setIntensity(0.1f);
// reporting progress to the console
Log::message("-> Created a %s light source.\n", light_omni->getName());
// creating a world light and setting up its parameters
thesun = LightWorld::create(Math::vec4(1.0f, 1.0f, 1.0f, 1.0f));
thesun->setName("Sun");
thesun->setDisableAngle(90.0f);
thesun->setIntensity(1.0f);
thesun->setScattering(LightWorld::SCATTERING_SUN);
thesun->setWorldRotation(Math::quat(86.0f, 30.0f, 300.0f));
// reporting progress to the console
Log::message("-> Created a %s light source.\n", thesun->getName());
// creating a proj light and setting up its parameters
projector = LightProj::create(Math::vec4(1.0f, 1.0f, 0.5f, 1.0f), 10.0f, 60.0f, "");
projector->setWorldPosition(Math::Vec3(2.5f, 2.5f, 3.0f));
projector->setName("projector");
projector->setRotation(Math::quat(-45.0f, 45.0f, 0.0f));
projector->setPenumbra(0.425f);
projector->setIntensity(1.0f);
// reporting progress to the console
Log::message("-> Created a %s light source.\n", projector->getName());
Log::warning("Lights initialization OK!\n");
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method performing initialization of materials
int AppWorldLogic::initMaterials()
{
// creating a new child material of the mesh_base and setting its color
MaterialPtr mesh_base = Materials::findMaterial("mesh_base");
MaterialPtr my_mesh_base = mesh_base->inherit("my_mesh_base0");
my_mesh_base->setParameterFloat4("albedo_color", Math::vec4(255, 0, 0, 255));
// reporting progress to the console
Log::message("\n-> Generated %s material.\n", my_mesh_base->getName());
// creating a new child material of the mesh_base and setting its color
my_mesh_base = mesh_base->inherit("my_mesh_base1");
my_mesh_base->setParameterFloat4("albedo_color", Math::vec4(0, 255, 0, 255));
// reporting progress to the console
Log::message("-> Generated %s material.\n", my_mesh_base->getName());
//creating a new child material of the mesh_base and setting its color
my_mesh_base = mesh_base->inherit("my_mesh_base2");
my_mesh_base->setParameterFloat4("albedo_color", Math::vec4(0, 0, 255, 255));
// reporting progress to the console
Log::message("-> Generated %s material.\n", my_mesh_base->getName());
//creating a new child material of the mesh_base and setting its color
my_mesh_base = mesh_base->inherit("my_mesh_base3");
my_mesh_base->setParameterFloat4("albedo_color", Math::vec4(255, 255, 0, 255));
// reporting progress to the console
Log::message("-> Generated %s material.\n", my_mesh_base->getName());
Log::warning("Material generation OK!\n\n");
// clearing material pointer
my_mesh_base.clear();
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
//---------------------------------------------------- UPDATE METHODS ---------------------------------------------------------
//-----------------------------------------------------------------------------------------------------------------------------
/// method updating the position of the sun
int AppWorldLogic::updateLights()
{
// updating the Sun rotation angle
sun_angle += SUN_ROTATION_RATE * ifps;
if (sun_angle > 360.0f) sun_angle = 0.0f;
// changing the Sun position using the new angle
checked_ptr_cast<LightWorld>(World::getNodeByName("Sun"))->setWorldRotation(Math::quat(Math::vec3(0.5f, 0.0f, 0.5f), 180.0f - sun_angle));
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method updating the initial set of scene objects
int AppWorldLogic::updateObjects()
{
ObjectMeshDynamicPtr object;
// changing transformation for all scene objects named "my_meshdynamic_*" (initial set)
for (auto it = Objects.begin(); it != Objects.end(); it++)
{
object = it.get();
if (strstr(object->getName(), "my_meshdynamic_"))
{
// transform the node
transformNode(object);
}
}
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
//---------------------------------------------------- SHUTDOWN METHODS -------------------------------------------------------
//-----------------------------------------------------------------------------------------------------------------------------
/// method removing all created materials
int AppWorldLogic::clearMaterials()
{
Materials::removeMaterial(Materials::findMaterial("my_mesh_base0")->getGUID());
Materials::removeMaterial(Materials::findMaterial("my_mesh_base1")->getGUID());
Materials::removeMaterial(Materials::findMaterial("my_mesh_base2")->getGUID());
Materials::removeMaterial(Materials::findMaterial("my_mesh_base3")->getGUID());
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
/// method removing all created objects
int AppWorldLogic::removeObjects()
{
while (Objects.size() > 0)
{
removeMeshFromScene(Objects.begin()->get()->getName());
}
return 1;
}
//-----------------------------------------------------------------------------------------------------------------------------
AppWorldLogic::AppWorldLogic() {
}
AppWorldLogic::~AppWorldLogic() {
}
int AppWorldLogic::init() {
// Write here code to be called on world initialization: initialize resources for your world scene during the world start.
// initializing pseudo-random number generator
Game::setSeed(time(NULL));
// creating materials
initMaterials();
// creating objects
initObjects();
// creating a player
initPlayer();
// creating lights
initLights();
return 1;
}
// start of the main loop
int AppWorldLogic::update() {
// Write here code to be called before updating each render frame: specify all graphics-related functions you want to be called every frame while your application executes.
// getting an inverse FPS value (the time in seconds it took to complete the last frame)
ifps = Game::getIFps();
// checking if it's time to change current scale and forward vector direction of our objects
if (elapsed_time < 0.0f)
{
// change current scaling vector for objects
current_objects_scale = Math::vec3(Game::getRandomFloat(0.8f, 1.2f));
// change forward direction for objects
forward_direction = forward_direction * Math::rotateZ(60.0f);
// resetting elapsed time counter
elapsed_time = CHANGE_INTERVAL;
}
// decreasing the time counter to the next change of current scale and forward vector direction
elapsed_time -= ifps;
// updating objects
updateObjects();
// updating lights
updateLights();
return 1;
}
int AppWorldLogic::postUpdate() {
// The engine calls this function before rendering each render frame: correct behavior after the state of the node has been updated.
return 1;
}
int AppWorldLogic::updatePhysics() {
// Write here code to be called before updating each physics frame: control physics in your application and put non-rendering calculations.
// The engine calls updatePhysics() with the fixed rate (60 times per second by default) regardless of the FPS value.
// WARNING: do not create, delete or change transformations of nodes here, because rendering is already in progress.
return 1;
}
// end of the main loop
int AppWorldLogic::shutdown() {
// Write here code to be called on world shutdown: delete resources that were created during world script execution to avoid memory leaks.
// deleting all created nodes
removeObjects();
// clearing the player pointer
player->deleteLater();
// clearing light sources
thesun->deleteLater();
light_omni->deleteLater();
projector->deleteLater();
// clearing all created materials
clearMaterials();
return 1;
}
int AppWorldLogic::save(const StreamPtr &stream) {
// Write here code to be called when the world is saving its state (i.e. state_save is called): save custom user data to a file.
UNIGINE_UNUSED(stream);
return 1;
}
int AppWorldLogic::restore(const StreamPtr &stream) {
// Write here code to be called when the world is restoring its state (i.e. state_restore is called): restore custom user data to a file here.
UNIGINE_UNUSED(stream);
return 1;
}