so I was following this tutorial, and everything was going all smooth and dandy, until I encountered a problem, namely that I couldn't load a .bmp.
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <stdio.h>
#include <iostream>
#include <SDL2/SDL_main.h>
using namespace std;
int main(int argc, char* argv[]) {
bool quit = false;
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window;
window = SDL_CreateWindow("window", 100, 100, 1280, 720, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
if(window == NULL){
cout << "Disn't work, here is why: " << SDL_GetError()<< endl;
return 0;
}
SDL_Renderer* renderer = NULL;
renderer= SDL_CreateRenderer(window, -1 ,SDL_RENDERER_ACCELERATED);
SDL_Event* mainEvent = new SDL_Event();
SDL_Texture* grass_image = NULL;
grass_image = IMG_LoadTexture(renderer, "grass.bmp");
SDL_Rect grass_rect;
grass_rect.x = 10;
grass_rect.y = 50;
grass_rect.w = 250;
grass_rect.h = 250;
while(!quit && mainEvent->type != SDL_QUIT){
SDL_PollEvent(mainEvent);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, grass_image, NULL, &grass_rect);
SDL_RenderPresent(renderer);
}
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
delete mainEvent;
return 0;
}
When I try to compile the code (in Code::Blocks) it gives me the error of
Undefined reference to "IMG_LoadTexture"
Well, I tried to change IMG_LoadTexture(renderer, "grass.bmp"); to IMG_LoadTexture(renderer, "/the/full/path/of/grass.bmp");but this didn't work either. Same error. Have I written something wrong, or missed some part? Also, grass.bmp is in the same folder as main.cpp (the code above).
The error here says that you have declared a function but have not defined it - undefined reference.
Most probably it happened because you forgot to link against library SDL_image to which function IMG_LoadTexture belongs.
Related
I have a C++ project where I'm initially trying to display a PNG image to the screen.
This is my code.
RenderWindow.hpp
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
class RenderWindow
{
public:
RenderWindow(const char *p_title, int p_width, int p_height);
void render();
void cleanUp();
private:
SDL_Window *window;
SDL_Renderer *renderer;
SDL_Surface *image = IMG_Load("~/SDL2_Game/images/Green_Tile.png");
SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, image);
};
RenderWindow.cpp
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <iostream>
#include "RenderWindow.hpp"
RenderWindow::RenderWindow(const char* p_title, int p_w, int p_h):window(NULL), renderer(NULL)
{
window = SDL_CreateWindow(p_title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, p_w, p_h, SDL_WINDOW_SHOWN);
if (window == NULL) std::cout << "Window failed to init: " << SDL_GetError() << std::endl;
renderer = SDL_CreateRenderer(window,-1,SDL_RENDERER_ACCELERATED);
}
void RenderWindow::render(){
SDL_RenderClear(renderer);
//SDL_Rect dstrect = { 5, 5, 320, 240 };
SDL_RenderCopy(renderer, texture, NULL, NULL);
SDL_RenderPresent(renderer);
}
void RenderWindow::cleanUp(){
SDL_DestroyTexture(texture);
SDL_FreeSurface(image);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
}
main.cpp
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <iostream>
#include "RenderWindow.hpp"
int main(int argc, char** argv){
if (SDL_Init(SDL_INIT_VIDEO) != 0) {
std::cout << "Problem with initialization. " << SDL_GetError() << std::endl;
}
else {
std::cout << "Initialization success!" <<std::endl;
}
if (!IMG_Init(IMG_INIT_PNG)){
std::cout << "Problem with Image initialization " <<SDL_GetError() << std::endl;
}
RenderWindow win("RPG_Game_v_1.0", 800, 600);
win.render();
bool gameRunning = true;
SDL_Event event;
while(gameRunning){
while(SDL_PollEvent(&event)){
if (event.type == SDL_QUIT) gameRunning = false;
}
}
win.cleanUp();
IMG_Quit();
SDL_Quit();
return 0;
}
I'm on a Linux machine.
I compile this with
g++ -g -o game ./*.cpp -lSDL2main -lSDL2 -lSDL2_image
Only a window is displaying. There is no image. I've tried refactoring my code with SDL_BlitSurface() and it does indeed display the PNG image. But why is this code not working? is it due to the fact that I'm using SDL_Texture* and my current system does not have a discrete graphics card?
I think that the call to SDL_CreateTextureFromSurface fails because it is called before SDL_CreateWindow and SDL_CreateRenderer, thereby initializing texture to NULL.
Please move the initizalization of texture (and image) to after window and renderer are initialized.
To further help with such issues, please check if the result of SDL functions != NULL and print SDL_GetError() to get more information about what went wrong.
The program doesnt show the image in the window i have created , also i dont get any of the fail messages that i have set , which means the values are not null.
What is the problem?
Here is the code:
#include "SDL.h"
#include "SDL_image.h"
#include <iostream>
int main(int argc,char* argv[])
{
SDL_Window *window;
SDL_Renderer *renderer;
SDL_Event event;
bool quit = false;
SDL_Surface *tmpsur = NULL;
SDL_Texture *tex = NULL;
SDL_Init(SDL_INIT_EVERYTHING);
window = SDL_CreateWindow("First window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, SDL_WINDOW_SHOWN);
renderer = SDL_CreateRenderer(window, -1, 0);
tmpsur = IMG_Load("assets/player.png");
if (tmpsur == NULL)
{
std::cout << "fail" << std::endl;
}
tex = SDL_CreateTextureFromSurface(renderer,tmpsur);
if (tex == NULL)
{
std::cout << "fail 2" << std::endl;
}
SDL_FreeSurface(tmpsur);
SDL_RenderPresent(renderer);
while (!quit)
{
while (SDL_PollEvent(&event) != 0)
{
if(event.type == SDL_QUIT)
{
quit = true;
}
}
}
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_Quit();
return 0;
}
You need to copy your texture onto the render target. Before presenting your renderer you need to call SDL_RenderCopy like this:
SDL_RenderCopy(renderer, text, nullptr, nullptr);
SDL_RenderPresent(renderer);
The nullptrs in the argument will make it copy the texture over all your target (the window).
I am having troubles with SDL_Texture
RPGTutorial.cpp
#include "stdafx.h"
int main(int argc, char *argv[])
{
bool quit = false;
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = NULL;
window = SDL_CreateWindow("RPG Tutorial!", 100, 100, 600, 400, SDL_WINDOW_SHOWN);
if (window == NULL)
{
std::cout << "Window couldn't be created" << std::endl;
return 0;
}
SDL_Renderer* renderer = NULL;
renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
if (renderer == NULL)
{
std::cout << "Renderer is not being created!" << std::endl;
SDL_DestroyWindow(window);
system("PAUSE");
return 0;
}
SDL_Event* mainEvent = new SDL_Event();
SDL_Texture* grass = NULL;
grass = IMG_LoadTexture(renderer, "Grass.bmp");
if (grass == NULL)
{
std::cout << "Grass Image was not found!" << std::endl;
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
delete mainEvent;
system("PAUSE");
return 0;
}
SDL_Rect grass_rect;
grass_rect.x = 0;
grass_rect.y = 0;
grass_rect.w = 64 * 2;
grass_rect.h = 64 * 2;
while (!quit && mainEvent->type != SDL_QUIT)
{
SDL_PollEvent(mainEvent);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, grass, NULL, &grass_rect);
SDL_RenderPresent(renderer);
}
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
delete mainEvent;
return 0;
}
stdafx.h
#include <SDL.h>
#include <SDL_image.h>
#include <SDL_mixer.h>
#include <iostream>
I have the Grass.bmp in the RPGTutorial->RPGTutorial->Grass.bmp
When I compile it, it is successful. It runs through the code til I get to the part where it checks if(grass == NULL) and it goes through that and exits. Can someone help me know why my grass is not being set to the image when I have the image in the same folder that the .cpp files are in? I even tried adding an Image folder to hold it in, and it did not work either.
If you have the time, I recommend you take some time to go through the Lazyfoo tutorials they are fantastic. He mentions this issue in the second tutorial, "Getting an Image on the Screen."
Visual Studio changes your current working directory to the place where your .vcxproj file is. That will be the directory you want to place your resources in. If you're not sure where that is, you can use the _getcwd() function in the direct.h header MSDN Source For getcwd
Today I started a C++/SDL2 Snake clone, and I've been looking for ways to make my code neater, -particularly with classes. I tried to put all the SDL code used for the window/display in a class. When I run the code, the window closes instantly. From the error tests I set up in display.cpp, it also tells me through the console that SDL_UpdateWindowSurface() (in display.update()) is always returning -1. Why does this happen when I rearrange my code like this?
With this code I load an image in main() and display it through my class' function applySurface(). The idea is to have classes/objects for the game's grid/board, the snake, etc., -each calling applySurface() for their own images. Feel free to tell me if this is a bad idea altogether.
main.cpp:
#include <SDL.h>
#include "display.h"
SDL_Event event;
SDL_Surface* image = nullptr;
int main(int argc, char* args[])
{
Display display;
display.loadImage("image.bmp");
if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
return false;
bool quit = false;
while (!quit)
{
while (SDL_PollEvent(&event))
{
if (event.type == SDL_QUIT)
quit = true;
}
display.applySurface(0, 0, image, display.windowSurface);
display.update();
}
SDL_FreeSurface(image);
SDL_Quit();
return 0;
}
display.h:
#pragma once
#include <SDL.h>
#include <string>
#include <iostream>
class Display
{
public:
SDL_Window* window;
SDL_Surface* windowSurface;
Display();
SDL_Surface *loadImage(std::string fileName);
void applySurface(int x, int y, SDL_Surface *source, SDL_Surface *destination, SDL_Rect *clip = nullptr);
void update();
~Display();
private:
const int WINDOW_WIDTH = 612;
const int WINDOW_HEIGHT = 632;
const int SCREEN_BPP = 2;
};
display.cpp:
#pragma once
#include "display.h"
Display::Display()
{
window = SDL_CreateWindow("Snake", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_SHOWN);
if (window == NULL)
std::cout << "Error: SDL_CreateWindow failed." << std::endl;
windowSurface = SDL_GetWindowSurface(window);
}
SDL_Surface* Display::loadImage(std::string fileName)
{
SDL_Surface* loadedImage = NULL;
SDL_Surface* optimizedImage = NULL;
loadedImage = SDL_LoadBMP(fileName.c_str());
if (loadedImage != NULL)
{
optimizedImage = SDL_ConvertSurface(loadedImage, windowSurface->format, 0);
SDL_FreeSurface(loadedImage);
if (optimizedImage != NULL)
SDL_SetColorKey(optimizedImage, SDL_TRUE, SDL_MapRGB(optimizedImage->format, 255, 255, 255));
}
return optimizedImage;
}
void Display::applySurface(int x, int y, SDL_Surface *source, SDL_Surface *destination, SDL_Rect *clip)
{
SDL_Rect offset;
offset.x = x;
offset.y = y;
SDL_BlitSurface(source, clip, destination, &offset);
}
void Display::update()
{
if (SDL_UpdateWindowSurface(window) == -1)
std::cout << "Error: SDL_UpdateWindowSurface() failed." << std::endl;
}
Display::~Display()
{
SDL_FreeSurface(windowSurface);
windowSurface = NULL;
SDL_DestroyWindow(window);
window = NULL;
}
This is a valid use of classes to structure your code. SDL_Init needs to come before any other SDL functions, which means you're best off moving SDL_Init to the top of main or adding it to the display constructor. If you add it to the beginning of the display constructor this means that you can only have one display class object running at a time, which would likely be fine in this case.
Ive been trawling the internet for weeks and none of the answers worked.
My code is:
#include <SDL.h>
#include <iostream>
using namespace std;
int main(int argc, char** argv[])
{
SDL_Window *win = nullptr;
SDL_Renderer *ren = nullptr;
SDL_Surface *bmp = nullptr;
SDL_Texture *tex = nullptr;
if (SDL_Init(SDL_INIT_EVERYTHING))
{
cout << SDL_GetError();
return 1;
}
win = SDL_CreateWindow("Hello World!", 100, 100, 640, 480, SDL_WINDOW_SHOWN);
if (win == nullptr)
{
cout << SDL_GetError();
return 1;
}
ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
if (ren == nullptr)
{
cout << SDL_GetError();
return 1;
}
bmp = SDL_LoadBMP("hello.bmp");
tex = SDL_CreateTextureFromSurface(ren, bmp);
SDL_FreeSurface(bmp);
SDL_RenderClear(ren);
SDL_RenderCopy(ren, tex, NULL, NULL);
SDL_RenderPresent(ren);
SDL_Delay(2000);
SDL_DestroyTexture(tex);
SDL_DestroyRenderer(ren);
SDL_DestroyWindow(win);
SDL_Quit();
return 0;
}
Ive tried #undef main (Which comes up with another error) & and even redefining it to no avail. Ive also tried several other attempts such as creating it as a Windows Console project.
Anyway I really hope you can help me and others.
Cheers,
user (insert psuedo-randomly generated integer here)
The signature of your main function is incorrect.
This line:
int main(int argc, char** argv[])
should be
int main(int argc, char* argv[])