rayjs/examples/models/models_billboard.js

/*******************************************************************************************
*
*   raylib [models] example - Drawing billboards
*
*   Example originally created with raylib 1.3, last time updated with raylib 3.5
*
*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
*   BSD-like license that allows static linking with closed source software
*
*   Copyright (c) 2015-2023 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

// Initialization
//--------------------------------------------------------------------------------------
const screenWidth = 800;
const screenHeight = 450;

InitWindow(screenWidth, screenHeight, "raylib [models] example - drawing billboards");

// Define the camera to look into our 3d world
Camera camera = { 0 };
camera.position = (Vector3){ 5.0f, 4.0f, 5.0f };    // Camera position
camera.target = (Vector3){ 0.0f, 2.0f, 0.0f };      // Camera looking at point
camera.up = (Vector3){ 0.0f, 1.0f, 0.0f };          // Camera up vector (rotation towards target)
camera.fovy = 45.0f;                                // Camera field-of-view Y
camera.projection = CAMERA_PERSPECTIVE;             // Camera projection type

Texture2D bill = LoadTexture("resources/billboard.png");    // Our billboard texture
Vector3 billPositionStatic = { 0.0f, 2.0f, 0.0f };          // Position of static billboard
Vector3 billPositionRotating = { 1.0f, 2.0f, 1.0f };        // Position of rotating billboard

// Entire billboard texture, source is used to take a segment from a larger texture.
Rectangle source = { 0.0f, 0.0f, (float)bill.width, (float)bill.height };

// NOTE: Billboard locked on axis-Y
Vector3 billUp = { 0.0f, 1.0f, 0.0f };

// Rotate around origin
// Here we choose to rotate around the image center
// NOTE: (-1, 1) is the range where origin.x, origin.y is inside the texture
Vector2 rotateOrigin = { 0.0f };

// Distance is needed for the correct billboard draw order
// Larger distance (further away from the camera) should be drawn prior to smaller distance.
float distanceStatic;
float distanceRotating;
float rotation = 0.0f;

SetTargetFPS(60);                   // Set our game to run at 60 frames-per-second
//--------------------------------------------------------------------------------------

// Main game loop
while (!WindowShouldClose())        // Detect window close button or ESC key
{
    // Update
    //----------------------------------------------------------------------------------
    UpdateCamera(&camera, CAMERA_ORBITAL);

    rotation += 0.4f;
    distanceStatic = Vector3Distance(camera.position, billPositionStatic);
    distanceRotating = Vector3Distance(camera.position, billPositionRotating);
    //----------------------------------------------------------------------------------

    // Draw
    //----------------------------------------------------------------------------------
    BeginDrawing();

        ClearBackground(RAYWHITE);

        BeginMode3D(camera);

            DrawGrid(10, 1.0f);        // Draw a grid

            // Draw order matters!
            if (distanceStatic > distanceRotating) 
            {
                DrawBillboard(camera, bill, billPositionStatic, 2.0f, WHITE);
                DrawBillboardPro(camera, bill, source, billPositionRotating, billUp, (Vector2) {1.0f, 1.0f}, rotateOrigin, rotation, WHITE);
            } 
            else
            {
                DrawBillboardPro(camera, bill, source, billPositionRotating, billUp, (Vector2) {1.0f, 1.0f}, rotateOrigin, rotation, WHITE);
                DrawBillboard(camera, bill, billPositionStatic, 2.0f, WHITE);
            }
            
        EndMode3D();

        DrawFPS(10, 10);

    EndDrawing();
    //----------------------------------------------------------------------------------
}

// De-Initialization
//--------------------------------------------------------------------------------------
UnloadTexture(bill);        // Unload texture

CloseWindow();              // Close window and OpenGL context
//--------------------------------------------------------------------------------------