Example of Origin and Destination Rectangle in DrawTexturePro

[JeffM2501]

Shows examples of how the origin and destination rectangle interact when used with DrawTexturePro.

If your origin is not at 0,0, the destination rectangle you give will NOT be in screen space, as the origin will offset it. The X and Y of the rectangle end up being where on the screen you want to put the texture origin.

This is important if you are using the same destination rectangle for things that don't have an origin offset, like Collision checks. You will have to use a screen space rectangle for collisions.

You can see in this example that even though the second bunny has a destination rectangle X of 100, the left side is not at 100 like the first one that has no origin offset. The origin offset for the second bunny is subtracted from it's rectangle so that the bunny is centered on the coordinates specified (100,200).

/*******************************************************************************************
*
*   raylib example - texture origin
*
*   Welcome to raylib!
*
*   To test examples, just press F6 and execute raylib_compile_execute script
*   Note that compiled executable is placed in the same folder as .c file
*
*   You can find all basic examples on C:\raylib\raylib\examples folder or
*   raylib official webpage: www.raylib.com
*
*   Enjoy using raylib. :)
*
*   This example has been created using raylib 3.8 by Jeffery Myers (@JeffM)
*
*   Copyright (c) 2013-2021 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include "raylib.h"

int main(void)
{
    // Init
    const int screenWidth = 800;
    const int screenHeight = 600;

    SetConfigFlags(FLAG_VSYNC_HINT);
    InitWindow(screenWidth, screenHeight, "raylib example - texture origin");

    // load a texture
    Texture bunny = LoadTexture("resources/wabbit_alpha.png");

    // cache some bunny constants
    const Vector2 bunnyCenter = { bunny.width / 2.0f, bunny.height / 2.0f };
    const Rectangle bunnyRect = { 0,0, (float)bunny.width, (float)bunny.height };

    SetTargetFPS(144);

    // Main game loop
    while (!WindowShouldClose())
    {
        // Draw
        //----------------------------------------------------------------------------------
        BeginDrawing();

        ClearBackground(RAYWHITE);

        // grid lines
        DrawLine(100, 0, 100, screenHeight, RED);
        DrawLine(0, 100, screenWidth, 100, RED);
        DrawLine(0, 200, screenWidth, 200, RED);
        DrawLine(0, 300, screenWidth, 300, RED);
        DrawLine(0, 400, screenWidth, 400, RED);

        // notes
        DrawText("100", 100, 0, 20, RED);
        DrawText("Upper Left Origin", 200, 100, 20, RED);
        DrawText("Center Origin", 200, 200, 20, RED);
        DrawText("Center Origin Rotating", 200, 300, 20, RED);
        DrawText("Upper Left Origin Rotating", 200, 400, 20, RED);

        // upper left origin (0,0), drawn at 100,100
        DrawTexturePro(bunny, bunnyRect, (Rectangle) { 100, 100, bunnyRect.width, bunnyRect.height }, (Vector2) { 0, 0 }, 0, WHITE);

        // upper center origin (bunnyCenter), drawn at 100, 200
        DrawTexturePro(bunny, bunnyRect, (Rectangle) { 100, 200, bunnyRect.width, bunnyRect.height }, bunnyCenter, 0, WHITE);

        // center origin (bunnyCenter), drawn at 100, 300, spinning
        DrawTexturePro(bunny, bunnyRect, (Rectangle) { 100, 300, bunnyRect.width, bunnyRect.height }, bunnyCenter, (float)GetTime() * 90, WHITE);

        // upper left origin (0,0), drawn at 100, 400, spinning
        DrawTexturePro(bunny, bunnyRect, (Rectangle) { 100, 400, bunnyRect.width, bunnyRect.height }, (Vector2) { 0, 0 }, (float)GetTime() * 90, WHITE);

        EndDrawing();
    }

    // cleanup
    UnloadTexture(bunny);
    CloseWindow();

    return 0;
}