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Ryzom Core Wiki edited this page Jul 8, 2024 · 8 revisions

title: Tutorial NeL Part 2 - Displaying "Hello, World!" Text description: published: true date: 2023-03-18T06:30:04.497Z tags: editor: markdown dateCreated: 2023-03-18T02:03:07.327Z

Displaying "Hello, World!" Text

In this part of the tutorial, you will learn how to display "Hello, World!" text on the screen using Ryzom Core and the NeL 3D library. You will create a simple text renderer, render the text, and position it on the screen.

Step 1: Include necessary headers

Start by including the necessary headers in your main.cpp file:

#include <nel/3d/u_text_context.h>

Step 2: Add a text context member variable

In the CMyGame class, add a member variable to hold the text context:

class CMyGame : public IEventListener
{
public:
    // ...
    
private:
    // ...
    NL3D::UTextContext *m_TextContext;
};

Step 3: Initialize the text context

In the CMyGame constructor, initialize the text context using the createTextContext() method of the driver:

CMyGame::CMyGame()
    : m_CloseWindow(false)
{
    // ...
    
    // Initialize the text context
    m_TextContext = m_Driver->createTextContext("font_filename.ttf");
    
    // Set text properties
    m_TextContext->setFontSize(24);
    m_TextContext->setColor(NLMISC::CRGBA(255, 255, 255));
    
    // ...
}

Replace font_filename.ttf with the path to a TTF font file in your project's resources.

Step 4: Release the text context

In the CMyGame destructor, release the text context:

CMyGame::~CMyGame()
{
    // Release resources
    m_TextContext->release();
    m_Driver->release();
    delete m_Driver;
}

Step 5: Render the text

In the run() method of the CMyGame class, render the "Hello, World!" text after clearing the screen and before swapping buffers:

void CMyGame::run()
{
    // Main game loop
    while (m_Driver->isActive() && !m_CloseWindow)
    {
        // ...
        
        // Clear the screen
        m_Driver->clearBuffers(NLMISC::CRGBA(0, 0, 128));

        // Render the text
        m_TextContext->setHotSpot(NL3D::UTextContext::TopLeft);
        m_TextContext->printfAt(0.05f, 0.95f, "Hello, World!");

        // Swap the buffers
        m_Driver->swapBuffers();
    }
}

This will display the "Hello, World!" text in the top-left corner of the screen.

Conclusion

By following this tutorial, you have learned how to display text on the screen using Ryzom Core and the NeL 3D library. This knowledge will be useful for creating in-game text elements such as menus, HUDs, and other user interfaces. In the next part of the tutorial, you will learn how to render basic 3D shapes.

This code initializes the NeL driver, sets up the display mode, creates a window, and runs a basic rendering loop that clears the screen and swaps buffers. The window will be closed when the user closes it.

Displaying "Hello, World!" Text in NeL

In this tutorial, we will cover how to display "Hello, World!" text on the screen using the NeL engine. This will involve loading a font, creating a text context, and rendering the text on screen using the text context and the NeL driver.

Prerequisites

Before starting this tutorial, make sure you have completed the following steps:

  1. Set up a NeL game project as described in the Creating a Blank NeL Game Project section.
  2. Initialize the NeL driver as described in the Initializing the NeL Driver section.

Source Code

Here's the complete source code for displaying "Hello, World!" text in a NeL project:

#include <nel/misc/app_context.h>
#include <nel/misc/debug.h>
#include <nel/misc/path.h>
#include <nel/misc/file.h>
#include <nel/misc/config_file.h>
#include <nel/3d/u_driver.h>
#include <nel/3d/u_text_context.h>
#include <nel/3d/u_shape_bank.h>

using namespace std;
using namespace NLMISC;
using namespace NL3D;

// Main function
int main(int argc, char *argv[])
{
    // Create the application context
    CApplicationContext applicationContext;

    // Initialize the driver
    UDriver *driver = nullptr;

    try
    {
        driver = UDriver::createDriver(0, nullptr, true);
        if (!driver)
        {
            nlerror("Unable to create a NeL driver.");
            return 1;
        }

        // Set up the display mode
        UDriver::CMode mode;
        mode.Width = 800;
        mode.Height = 600;
        mode.Depth = 32;

        // Initialize the window
        driver->setDisplay(mode, 32, false, "NeL Hello World");
    }
    catch (const Exception &e)
    {
        nlerror("NeL driver initialization error: %s", e.what());
        return 1;
    }

    // Load a font and create a text context
    UTextContext *textContext = driver->createTextContext("n019003l.pfb");
    if (!textContext)
    {
        nlerror("Failed to create text context.");
        delete driver;
        return 1;
    }

    // Set the font size and color
    textContext->setFontSize(24);
    textContext->setColor(CRGBA(255, 255, 255));

    // Main rendering loop
    while (!driver->AsyncDownloader->isTerminated() && !driver->AsyncTextureUploader->isTerminated() && !driver->Exit)
    {
        // Clear the screen
        driver->clearBuffers();

        // Render the text on screen
        textContext->printAt(driver, 0.5f, 0.5f, "Hello, World!");

        // Swap buffers
        driver->swapBuffers();
    }

    // Release resources
    delete textContext;
    delete driver;

    return 0;
}

This code initializes the NeL driver, sets up the display mode, creates a window, loads a font, and creates a text context. The text context is used to render "Hello, World!" text on the screen within the main rendering loop. The window will be closed when the user closes it.

Displaying "Hello, World!" Text in NeL

Introduction

In this tutorial, we will show you how to display "Hello, World!" text on the screen in a NeL project. This involves loading a font, creating a text context, and rendering the text using the NeL driver.

Prerequisites

Before starting this tutorial, make sure you have completed the following steps:

  1. Set up a NeL game project as described in the Creating a Blank NeL Game Project section.
  2. Initialize the NeL driver as described in the Initializing the NeL Driver section.

Step-by-step Instructions

  1. Include necessary headers: Add the following headers to your source code to handle text rendering in NeL:
#include <nel/3d/u_text_context.h>
  1. **Load a font

Person:

  • I received up to Prerequisites of the Hello world tutorial, please resume

ChatGPT:

  • Before starting this tutorial, make sure you have completed the following steps:
  1. Set up a NeL game project as described in the Creating a Blank NeL Game Project section.
  2. Initialize the NeL driver as described in the Initializing the NeL Driver section.

Step-by-step Instructions

  1. Include necessary headers: Add the following headers to your source code to handle text rendering in NeL:
#include <nel/3d/u_text_context.h>
  1. Load a font: Load a font file (TTF or Type 1 format) from the filesystem using the loadFont method of the UTextContext class:
std::string fontPath = "path/to/your/font.ttf";
uint fontSize = 18;
NL3D::UTextContext *textContext = nullptr;
textContext = driver->createTextContext(fontPath, fontSize);
  1. Check for font loading errors: If the font cannot be loaded, display an error message and exit the application:
if (!textContext)
{
    nlerror("Unable to load font.");
    delete driver;
    return 1;
}
  1. Set the text to display: Set the text to display using the setText method of the UTextContext class:
textContext->setText("Hello, World!");
  1. Set the text position and color: Specify the position and color of the text using the setHotSpot and setColor methods of the UTextContext class:
textContext->setHotSpot(NL3D::UTextContext::BottomLeft);
textContext->setColor(NL3D::CRGBA(255, 255, 255));
  1. Render the text: In your main rendering loop, call the render method of the UTextContext class to draw the text on the screen:
textContext->render(driver, 10, 10);

Congratulations! You have successfully displayed "Hello, World!" text on the screen in your NeL project.

Displaying "Hello, World!" and Rendering Basic 3D Shapes

This tutorial will guide you through the process of displaying a "Hello, World!" message and rendering basic 3D shapes using NeL in your blank game project.

Prerequisites

Before proceeding, make sure you have completed the steps in sections 7.1 through 7.4, ensuring that you have set up the project directory structure, created the main application source file, configured the build with CMake, and built your NeL game project.

Displaying "Hello, World!" Text

To display a "Hello, World!" text message on the screen, you will need to use the NeL text rendering classes. Here's a step-by-step implementation:

  1. Include the required headers at the top of your main application source file:
#include <nel/misc/app_context.h>
#include <nel/misc/debug.h>
#include <nel/misc/path.h>
#include <nel/3d/u_driver.h>
#include <nel/3d/u_text_context.h>
  1. Add a new method called displayHelloWorld() in your main application class:
void displayHelloWorld()
{
    // Get the text context
    NL3D::UTextContext *textContext = Driver->createTextContext(NLMISC::CPath::lookup("font.packed"));

    // Set the text color and font size
    textContext->setColor(NLMISC::CRGBA(255, 255, 255));
    textContext->setFontSize(18);

    // Set the text position on the screen
    textContext->setHotSpot(NL3D::UTextContext::BottomLeft);
    textContext->setPos(0.05f, 0.05f);

    // Display the text
    textContext->printAt(0, "Hello, World!");

    // Release the text context
    Driver->deleteTextContext(textContext);
}
  1. Call the displayHelloWorld() method inside your main rendering loop, after clearing the screen and before swapping buffers:
Driver->clearBuffers(NLMISC::CRGBA(0, 0, 0, 255));
displayHelloWorld();
Driver->swapBuffers();

Rendering Basic 3D Shapes

To render basic 3D shapes, you will need to create and manipulate 3D models using NeL classes. In this example, we will render a simple cube:

  1. Include the required headers at the top of your main application source file:
#include <nel/3d/u_shape.h>
#include <nel/3d/u_instance.h>
  1. Add a new method called renderCube() in your main application class:
void renderCube()
{
    // Load the cube model
    NL3D::UShape *cubeShape = Driver->createShape("cube.shape");
    NL3D::UInstance cubeInstance = Driver->createInstance(cubeShape);

    // Set the cube position and scale
    cubeInstance.setPos(NLMISC::CVector(0.0f, 0.0f, 0.0f));
    cubeInstance.setScale(NLMISC::CVector(1.0f, 1.0f, 1.0f));

    // Render the cube
    Driver->drawInstance(cubeInstance);

    // Release the cube resources
    Driver->deleteShape(cubeShape);
    Driver->deleteInstance(cubeInstance);
}
  1. Call the renderCube() method inside your main rendering loop, after clearing the screen and before displaying the "Hello, World!" text and swapping buffers:
Driver->clearBuffers(NLMISC::CRGBA(0, 0, 0, 255));
renderCube();
displayHelloWorld();
Driver->swapBuffers();

With these changes, your NeL game project should now display a "Hello, World!" text message on the screen and render a simple 3D cube. You can expand on this code to display more text or render additional 3D shapes as needed.

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