What Causes SDL_Renderer to be invalid? - c++

Question

I'm trying to make a 2D game where the background is a hockey rink. The error handler said the Render-er didn't initialize thus making the texture not initialize. I know the BMP loads because I don't get an error for that. Don't worry about the camera stuff. The background is supposed to scroll. I just need the background to render. The code may not be the best, but corrections are always appreciated.
#include <SDL/SDL.h>
#include <stdio.h>
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int fps = 60;
SDL_Window *window;
int main(int argc, char **argv)
{
SDL_Init(SDL_INIT_EVERYTHING);
int x = 0, y = 0;
SDL_Surface *screen;
SDL_Surface *background = SDL_LoadBMP("hockeyrink.bmp");
if(background == NULL)
{
SDL_ShowSimpleMessageBox(0, "Background init error", SDL_GetError(), window);
}
SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, 0);
if(renderer == NULL)
{
SDL_ShowSimpleMessageBox(0, "Renderer init error", SDL_GetError(), window);
}
SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer,background);
if(texture == NULL)
{
SDL_ShowSimpleMessageBox(0, "Texture init error", SDL_GetError(), window);
}
const int speed = 5;
SDL_Rect camera;
camera.x = 0;
camera.y = 0;
camera.w = 800;
camera.h = 600;
bool b[2] = {0,0};
Uint32 start;
window = SDL_CreateWindow("", 300, 100, 1024, 800, SDL_WINDOW_OPENGL);
if (window == NULL)
{
cout << ("could not create window: %s/n", SDL_GetError());
return 1;
}
bool running = true;
while (running)
{
start = SDL_GetTicks();
SDL_Event event;
while(SDL_PollEvent(&event))
{
switch(event.type)
{
case SDL_QUIT:
running = false;
SDL_DestroyTexture(texture);
SDL_FreeSurface(background);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
break;
case SDL_KEYDOWN:
switch(event.key.keysym.sym)
{
case SDLK_UP:
b[0]=1;
break;
case SDLK_LEFT:
b[1]=1;
break;
}
break;
case SDL_KEYUP:
switch(event.key.keysym.sym)
{
case SDLK_UP:
b[0]=0;
break;
case SDLK_LEFT:
b[1]=0;
break;
}
break;
}
}
if(b[0])
{
x+=speed;
camera.y+=speed;
if (camera.y > 3000-800)
{
camera.y=0;
}
}
else if(b[1])
{
x-=speed;
camera.y-=speed;
if (camera.y <= 0)
{
camera.y = 2000-800;
}
SDL_RenderCopy(renderer, texture, NULL, NULL);
SDL_RenderPresent(renderer);
}
if(1000/fps>SDL_GetTicks()-start)
{
SDL_Delay(1000/fps-(SDL_GetTicks() - start));
}
}
return 0;
}

Answer 1

When you create renderer, the window pointer does not point to anything(i.e. it is uninitialized).
You must create the window before creating the renderer.
So put the lines:
window = SDL_CreateWindow("", 300, 100, 1024, 800, SDL_WINDOW_OPENGL);
if (window == NULL)
{
cout << ("could not create window: %s/n", SDL_GetError());
return 1;
}
before the line: SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, 0);