[macosxnerd101]

This week's challenge is SDL, written by stayscrisp.



SDL is a cross platform graphics library written in C++. There are also a number of extension libraries available that enable network and audio functionality. SDL is a great way to add graphics to your application whilst hiding the platform specific details, it can even create OpenGL windows for 3D graphics.

SDL has been used in many commercial projects including Second Life, Neverwinter Nights and World of Goo. Many games are ported to Linux using SDL due to its cross-platformness (it's a word!).

Getting Started

• Download SDL
  
• Link the library for your operating system

Resources

• Documentation
  
• Object-oriented SDL tutorials
  
• Tutorials for specific areas

It would be great to see some simple games such as Pong, Arkanoid or Asteroids or some none game related graphics.

[stayscrisp]

A simple program to initialise SDL, create a window and display a BMP image.

/*
Create a window and blit an SDL surface to it
*/

#include <SDL.h>
#include <string>
#include <iostream>

bool g_bRunning = false; 
bool g_bFullscreen = false;
SDL_Surface* g_pScreen = NULL;
SDL_Surface* g_pTestSurface = NULL;

SDL_Surface* LoadImage(std::string filename)
{
	// pointers to some SDL surfaces
	SDL_Surface* pTempSurface = NULL;
	SDL_Surface* pReturnedSurface = NULL;

	// create the surface from the loaded BMP and point to it through pTempSurface
	if((pTempSurface = SDL_LoadBMP(filename.c_str())) == NULL)
	{
		std::cout << "Could not open file" << filename << "\n";
		return NULL; // return nothing
	}

	// set the display format of the final surface using the temporary surface
	pReturnedSurface = SDL_DisplayFormatAlpha(pTempSurface);

	// free the temporary surface
	SDL_FreeSurface(pTempSurface); 

	// return a pointer to the final surface
	return pReturnedSurface;
}

// creates a rectangle to blit the SDL_Surface to
bool DrawSurface(SDL_Surface* dest, SDL_Surface* src, float x, float y)
{
	if(dest == NULL || src == NULL)
	{
		return false;
	}

	SDL_Rect  destR;

	destR.x = (Sint16)x;
	destR.y = (Sint16)y;

	SDL_BlitSurface(src, NULL, dest, &destR);

	return true;
}

// Very simple event management, if the cross is clicked the program ends
void HandleEvents()
{
	SDL_Event event;

	if (SDL_PollEvent(&event)) 
	{
		switch (event.type) 
		{
		case SDL_QUIT:
			g_bRunning = false;
			break;
		}
	}
}

bool InitialiseSDLWindow(const std::string title, int width, int height, int bpp, bool fullscreen)
{
	// used for fullscreen in this instance
	int flags = 0;

	// initialise SDL video capabilities
	if(SDL_Init(SDL_INIT_VIDEO) == 1) 
	{
		std::cout << "Could not init SDL\n";
		return false;
	}

	// Set the window title
	SDL_WM_SetCaption(title.c_str(),title.c_str());

	if(fullscreen) // set fullscreen if wanted
	{
		flags = SDL_FULLSCREEN;
	}

	// Create the screen surface
	g_pScreen = SDL_SetVideoMode(width, height, bpp, flags);

	g_bFullscreen = fullscreen;

	g_bRunning = true;

	return true;
}

int main(int argc, char* argv[])
{

	if(!InitialiseSDLWindow("Test", 800, 600, 32, false))
	{
		std::cout << "Could not init SDL window\n";
		return 1;
	}

	// load the surface
	g_pTestSurface = LoadImage("test.bmp");
	if(g_pTestSurface == NULL) // error checking ;)/>
	{
		std::cout << "Could not open image\n";
		return 1;
	}

	// main loop
	while(g_bRunning)
	{
		HandleEvents();
		DrawSurface(g_pScreen, g_pTestSurface, 100, 100);
		SDL_Flip(g_pScreen);
	}

	return 0;
}

I thought I'd put in error checking unlike my tutorials which left it out for the sake of clarity Hopefully this might help some people interested in having a go at SDL