raylib/docs/examples/web/textures/textures_image_drawing.c

/*******************************************************************************************
*
*   raylib [textures] example - Image loading and drawing on it
*
*   NOTE: Images are loaded in CPU memory (RAM); textures are loaded in GPU memory (VRAM)
*
*   This example has been created using raylib 1.4 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Copyright (c) 2016 Ramon Santamaria (@raysan5)
*
********************************************************************************************/

#include "raylib.h"

#if defined(PLATFORM_WEB)
    #include <emscripten/emscripten.h>
#endif

//----------------------------------------------------------------------------------
// Global Variables Definition
//----------------------------------------------------------------------------------
int screenWidth = 800;
int screenHeight = 450;

Texture2D texture;              // Texture, GPU memory (VRAM)

//----------------------------------------------------------------------------------
// Module Functions Declaration
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void);     // Update and Draw one frame

//----------------------------------------------------------------------------------
// Main Enry Point
//----------------------------------------------------------------------------------
int main()
{
    // Initialization
    //--------------------------------------------------------------------------------------
    InitWindow(screenWidth, screenHeight, "raylib [textures] example - image drawing");
    
    Image cat = LoadImage("resources/cat.png");             // Load image in CPU memory (RAM)
    ImageCrop(&cat, (Rectangle){ 100, 10, 280, 380 });      // Crop an image piece
    ImageFlipHorizontal(&cat);                              // Flip cropped image horizontally
    ImageResize(&cat, 150, 200);                            // Resize flipped-cropped image
    
    Image parrots = LoadImage("resources/parrots.png");     // Load image in CPU memory (RAM)
    
    // Draw one image over the other with a scaling of 1.5f
    ImageDraw(&parrots, cat, (Rectangle){ 0, 0, cat.width, cat.height }, (Rectangle){ 30, 40, cat.width*1.5f, cat.height*1.5f });
    ImageCrop(&parrots, (Rectangle){ 0, 50, parrots.width, parrots.height - 100 }); // Crop resulting image
    
    UnloadImage(cat);       // Unload image from RAM
    
    texture = LoadTextureFromImage(parrots);      // Image converted to texture, uploaded to GPU memory (VRAM)
    UnloadImage(parrots);   // Once image has been converted to texture and uploaded to VRAM, it can be unloaded from RAM
    
#if defined(PLATFORM_WEB)
    emscripten_set_main_loop(UpdateDrawFrame, 0, 1);
#else
    SetTargetFPS(60);   // Set our game to run at 60 frames-per-second
    //--------------------------------------------------------------------------------------
    
    // Main game loop
    while (!WindowShouldClose())    // Detect window close button or ESC key
    {
        UpdateDrawFrame();
    }
#endif

    // De-Initialization
    //--------------------------------------------------------------------------------------
    UnloadTexture(texture);		// Texture unloading
    
    CloseWindow();				// Close window and OpenGL context
    //--------------------------------------------------------------------------------------

    return 0;
}

//----------------------------------------------------------------------------------
// Module Functions Definition
//----------------------------------------------------------------------------------
void UpdateDrawFrame(void)
{
    // Update
    //----------------------------------------------------------------------------------
    // TODO: Update your variables here
    //----------------------------------------------------------------------------------

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

        ClearBackground(RAYWHITE);

        DrawTexture(texture, screenWidth/2 - texture.width/2, screenHeight/2 - texture.height/2 - 40, WHITE);
        DrawRectangleLines(screenWidth/2 - texture.width/2, screenHeight/2 - texture.height/2 - 40, texture.width, texture.height, DARKGRAY);

        DrawText("We are drawing only one texture from various images composed!", 240, 350, 10, DARKGRAY);
        DrawText("Source images have been cropped, scaled, flipped and copied one over the other.", 190, 370, 10, DARKGRAY);

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