raylib-src/examples/textures/textures_blend_modes.c

/*******************************************************************************************
*
*   raylib [textures] example - blend modes
*
*   NOTE: Images are loaded in CPU memory (RAM); textures are loaded in GPU memory (VRAM)
*
*   This example has been created using raylib 3.0 (www.raylib.com)
*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
*
*   Copyright (c) 2020 Karlo Licudine (@accidentalrebel)
*
********************************************************************************************/

#include "raylib.h"

int main(void)
{
	// Initialization
	//--------------------------------------------------------------------------------------
	const int screenWidth = 800;
	const int screenHeight = 450;

	InitWindow(screenWidth, screenHeight, "raylib [textures] example - blend modes");

	// NOTE: Textures MUST be loaded after Window initialization (OpenGL context is required)
	Image bgImage = LoadImage("resources/cyberpunk_street_background.png");     // Loaded in CPU memory (RAM)
	Texture2D bgTexture = LoadTextureFromImage(bgImage);          // Image converted to texture, GPU memory (VRAM)

	Image fgImage = LoadImage("resources/cyberpunk_street_foreground.png");     // Loaded in CPU memory (RAM)
	Texture2D fgTexture = LoadTextureFromImage(fgImage);          // Image converted to texture, GPU memory (VRAM)

	// Once image has been converted to texture and uploaded to VRAM, it can be unloaded from RAM
	UnloadImage(bgImage);   
	UnloadImage(fgImage);

	const int blendCountMax = 4;
	BlendMode blendMode = 0;
	
	// Main game loop
	while (!WindowShouldClose())    // Detect window close button or ESC key
	{
		// Update
		//----------------------------------------------------------------------------------
		int key = GetKeyPressed();
		if ((key >= 32) && (key <= 126))
		{
			if ( blendMode >= blendCountMax - 1 )
				blendMode = 0;
			else
				blendMode++;
		}
		
		// Draw
		//----------------------------------------------------------------------------------
		BeginDrawing();

		ClearBackground(RAYWHITE);

		BeginBlendMode(BLEND_ALPHA);
		DrawTexture(bgTexture, screenWidth/2 - bgTexture.width/2, screenHeight/2 - bgTexture.height/2, WHITE);

		// Apply the blend mode and then draw the foreground texture
		BeginBlendMode(blendMode);
		DrawTexture(fgTexture, screenWidth/2 - fgTexture.width/2, screenHeight/2 - fgTexture.height/2, WHITE);

		EndBlendMode();

		// Draw the texts
		DrawText("Press any key to change blend modes.", 310, 350, 10, GRAY);
		switch ( blendMode )
		{
		 case BLEND_ALPHA:
			 DrawText("Current: BLEND_ALPHA", (screenWidth / 2) - 60, 370, 10, GRAY);
			 break;
		 case BLEND_ADDITIVE:
			 DrawText("Current: BLEND_ADDITIVE", (screenWidth / 2) - 60, 370, 10, GRAY);
			 break;
		 case BLEND_MULTIPLIED:
			 DrawText("Current: BLEND_MULTIPLIED", (screenWidth / 2) - 60, 370, 10, GRAY);
			 break;
		 case BLEND_ADD_COLORS:
			 DrawText("Current: BLEND_ADD_COLORS", (screenWidth / 2) - 60, 370, 10, GRAY);
			 break;
		}
		DrawText("(c) Cyberpunk Street Environment by Luis Zuno (@ansimuz)", screenWidth - 330, screenHeight - 20, 10, GRAY);

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

	// De-Initialization
	//--------------------------------------------------------------------------------------
	UnloadTexture(fgTexture); // Unload foreground texture
	UnloadTexture(bgTexture); // Unload background texture

	CloseWindow();            // Close window and OpenGL context
	//--------------------------------------------------------------------------------------
	
	return 0;
}