SDL_RenderCopy not doing anything











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I'm calling SDL_RenderCopy and it gets called and returns normally but doesn't draw anything to the window. Edited to make the question and code clearer. I'm thinking I might be trying to use something beyond its scope and hence it can't be called but this doesn't produce any error so I'm not sure. Here's the simple picture I refer to https://commons.wikimedia.org/wiki/Category:PNG_chess_pieces/Standard_transparent#/media/File:Chess_kdt60.png



#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>

// Recreation of the problem. Doesnt draw anything onto the white screen.

class King{

public:
King(SDL_Renderer *renderer){
SDL_Surface *Piece;
Piece = IMG_Load("Pieces/BK.png"); // I'll attach the picture
king = SDL_CreateTextureFromSurface(renderer, Piece);
SDL_FreeSurface(Piece);
kingRect.h = 100;
kingRect.w = 100;
}
~King(){}

void render(SDL_Renderer *renderer){
SDL_RenderCopy(renderer, king, NULL, &kingRect); // 99% sure the problem is this
}

private:
SDL_Texture *king;
SDL_Rect kingRect;
};

class Game {

public:
Game(const char *title, int sidelength){
isRunning = true;
if(SDL_Init(SDL_INIT_EVERYTHING) != 0) isRunning = false;

window = SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, sidelength, sidelength, SDL_WINDOW_OPENGL);
if(window == NULL) isRunning = false;

renderer = SDL_CreateRenderer(window, -1, 0);
if(!renderer) isRunning = false;

SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
}
~Game(){}
void handleEvents(){
//Handles Events. I know this works.
}
}

void update(){};

void render(){
SDL_RenderClear(renderer);
BK.render(renderer);
SDL_RenderPresent(renderer);
}

void clean(){
//Cleans up after. I know this works.
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_Quit();
}
bool running(){return(isRunning);}
King BK{renderer};
private:
bool isRunning{true};
SDL_Window *window;
SDL_Renderer *renderer;
};

Game *game = nullptr;

int main(int argc, const char *argv){
game = new Game("Testing Window", 800);

while(game->running()){
game->handleEvents();
game->update();
game->render();
}
game->clean();
return(0);
}









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  • 2




    This isn't nearly enough code to tell where the bug is coming from. Are you checking return values from SDL functions and checking SDL_GetError() when something fails? Please edit your question to include information to reproduce the problem, and consider creating a Minimal, Complete, Verifiable Example.
    – alter igel
    Nov 20 at 2:12






  • 1




    Thank you for bringing the lack of clarity to my attention. I created a mini program that reproduces the same problem. SDL_GetError doesn't find any error which was part of the problem.
    – SorSorSor
    Nov 20 at 3:02










  • Thanks! This looks much better. I suspect that kingRect.x and kingRect.y are uninitialized and might have garbage values, which could place the target rectangle somewhere really far off screen. Try adding kingRect.x = 0; kingRect.y = 0; in your constructor
    – alter igel
    Nov 20 at 4:18















up vote
1
down vote

favorite












I'm calling SDL_RenderCopy and it gets called and returns normally but doesn't draw anything to the window. Edited to make the question and code clearer. I'm thinking I might be trying to use something beyond its scope and hence it can't be called but this doesn't produce any error so I'm not sure. Here's the simple picture I refer to https://commons.wikimedia.org/wiki/Category:PNG_chess_pieces/Standard_transparent#/media/File:Chess_kdt60.png



#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>

// Recreation of the problem. Doesnt draw anything onto the white screen.

class King{

public:
King(SDL_Renderer *renderer){
SDL_Surface *Piece;
Piece = IMG_Load("Pieces/BK.png"); // I'll attach the picture
king = SDL_CreateTextureFromSurface(renderer, Piece);
SDL_FreeSurface(Piece);
kingRect.h = 100;
kingRect.w = 100;
}
~King(){}

void render(SDL_Renderer *renderer){
SDL_RenderCopy(renderer, king, NULL, &kingRect); // 99% sure the problem is this
}

private:
SDL_Texture *king;
SDL_Rect kingRect;
};

class Game {

public:
Game(const char *title, int sidelength){
isRunning = true;
if(SDL_Init(SDL_INIT_EVERYTHING) != 0) isRunning = false;

window = SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, sidelength, sidelength, SDL_WINDOW_OPENGL);
if(window == NULL) isRunning = false;

renderer = SDL_CreateRenderer(window, -1, 0);
if(!renderer) isRunning = false;

SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
}
~Game(){}
void handleEvents(){
//Handles Events. I know this works.
}
}

void update(){};

void render(){
SDL_RenderClear(renderer);
BK.render(renderer);
SDL_RenderPresent(renderer);
}

void clean(){
//Cleans up after. I know this works.
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_Quit();
}
bool running(){return(isRunning);}
King BK{renderer};
private:
bool isRunning{true};
SDL_Window *window;
SDL_Renderer *renderer;
};

Game *game = nullptr;

int main(int argc, const char *argv){
game = new Game("Testing Window", 800);

while(game->running()){
game->handleEvents();
game->update();
game->render();
}
game->clean();
return(0);
}









share|improve this question




















  • 2




    This isn't nearly enough code to tell where the bug is coming from. Are you checking return values from SDL functions and checking SDL_GetError() when something fails? Please edit your question to include information to reproduce the problem, and consider creating a Minimal, Complete, Verifiable Example.
    – alter igel
    Nov 20 at 2:12






  • 1




    Thank you for bringing the lack of clarity to my attention. I created a mini program that reproduces the same problem. SDL_GetError doesn't find any error which was part of the problem.
    – SorSorSor
    Nov 20 at 3:02










  • Thanks! This looks much better. I suspect that kingRect.x and kingRect.y are uninitialized and might have garbage values, which could place the target rectangle somewhere really far off screen. Try adding kingRect.x = 0; kingRect.y = 0; in your constructor
    – alter igel
    Nov 20 at 4:18













up vote
1
down vote

favorite









up vote
1
down vote

favorite











I'm calling SDL_RenderCopy and it gets called and returns normally but doesn't draw anything to the window. Edited to make the question and code clearer. I'm thinking I might be trying to use something beyond its scope and hence it can't be called but this doesn't produce any error so I'm not sure. Here's the simple picture I refer to https://commons.wikimedia.org/wiki/Category:PNG_chess_pieces/Standard_transparent#/media/File:Chess_kdt60.png



#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>

// Recreation of the problem. Doesnt draw anything onto the white screen.

class King{

public:
King(SDL_Renderer *renderer){
SDL_Surface *Piece;
Piece = IMG_Load("Pieces/BK.png"); // I'll attach the picture
king = SDL_CreateTextureFromSurface(renderer, Piece);
SDL_FreeSurface(Piece);
kingRect.h = 100;
kingRect.w = 100;
}
~King(){}

void render(SDL_Renderer *renderer){
SDL_RenderCopy(renderer, king, NULL, &kingRect); // 99% sure the problem is this
}

private:
SDL_Texture *king;
SDL_Rect kingRect;
};

class Game {

public:
Game(const char *title, int sidelength){
isRunning = true;
if(SDL_Init(SDL_INIT_EVERYTHING) != 0) isRunning = false;

window = SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, sidelength, sidelength, SDL_WINDOW_OPENGL);
if(window == NULL) isRunning = false;

renderer = SDL_CreateRenderer(window, -1, 0);
if(!renderer) isRunning = false;

SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
}
~Game(){}
void handleEvents(){
//Handles Events. I know this works.
}
}

void update(){};

void render(){
SDL_RenderClear(renderer);
BK.render(renderer);
SDL_RenderPresent(renderer);
}

void clean(){
//Cleans up after. I know this works.
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_Quit();
}
bool running(){return(isRunning);}
King BK{renderer};
private:
bool isRunning{true};
SDL_Window *window;
SDL_Renderer *renderer;
};

Game *game = nullptr;

int main(int argc, const char *argv){
game = new Game("Testing Window", 800);

while(game->running()){
game->handleEvents();
game->update();
game->render();
}
game->clean();
return(0);
}









share|improve this question















I'm calling SDL_RenderCopy and it gets called and returns normally but doesn't draw anything to the window. Edited to make the question and code clearer. I'm thinking I might be trying to use something beyond its scope and hence it can't be called but this doesn't produce any error so I'm not sure. Here's the simple picture I refer to https://commons.wikimedia.org/wiki/Category:PNG_chess_pieces/Standard_transparent#/media/File:Chess_kdt60.png



#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>

// Recreation of the problem. Doesnt draw anything onto the white screen.

class King{

public:
King(SDL_Renderer *renderer){
SDL_Surface *Piece;
Piece = IMG_Load("Pieces/BK.png"); // I'll attach the picture
king = SDL_CreateTextureFromSurface(renderer, Piece);
SDL_FreeSurface(Piece);
kingRect.h = 100;
kingRect.w = 100;
}
~King(){}

void render(SDL_Renderer *renderer){
SDL_RenderCopy(renderer, king, NULL, &kingRect); // 99% sure the problem is this
}

private:
SDL_Texture *king;
SDL_Rect kingRect;
};

class Game {

public:
Game(const char *title, int sidelength){
isRunning = true;
if(SDL_Init(SDL_INIT_EVERYTHING) != 0) isRunning = false;

window = SDL_CreateWindow(title, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, sidelength, sidelength, SDL_WINDOW_OPENGL);
if(window == NULL) isRunning = false;

renderer = SDL_CreateRenderer(window, -1, 0);
if(!renderer) isRunning = false;

SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
}
~Game(){}
void handleEvents(){
//Handles Events. I know this works.
}
}

void update(){};

void render(){
SDL_RenderClear(renderer);
BK.render(renderer);
SDL_RenderPresent(renderer);
}

void clean(){
//Cleans up after. I know this works.
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_Quit();
}
bool running(){return(isRunning);}
King BK{renderer};
private:
bool isRunning{true};
SDL_Window *window;
SDL_Renderer *renderer;
};

Game *game = nullptr;

int main(int argc, const char *argv){
game = new Game("Testing Window", 800);

while(game->running()){
game->handleEvents();
game->update();
game->render();
}
game->clean();
return(0);
}






c++ sdl sdl-2 sdl-image






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share|improve this question













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share|improve this question








edited Nov 20 at 3:00

























asked Nov 19 at 23:37









SorSorSor

84




84








  • 2




    This isn't nearly enough code to tell where the bug is coming from. Are you checking return values from SDL functions and checking SDL_GetError() when something fails? Please edit your question to include information to reproduce the problem, and consider creating a Minimal, Complete, Verifiable Example.
    – alter igel
    Nov 20 at 2:12






  • 1




    Thank you for bringing the lack of clarity to my attention. I created a mini program that reproduces the same problem. SDL_GetError doesn't find any error which was part of the problem.
    – SorSorSor
    Nov 20 at 3:02










  • Thanks! This looks much better. I suspect that kingRect.x and kingRect.y are uninitialized and might have garbage values, which could place the target rectangle somewhere really far off screen. Try adding kingRect.x = 0; kingRect.y = 0; in your constructor
    – alter igel
    Nov 20 at 4:18














  • 2




    This isn't nearly enough code to tell where the bug is coming from. Are you checking return values from SDL functions and checking SDL_GetError() when something fails? Please edit your question to include information to reproduce the problem, and consider creating a Minimal, Complete, Verifiable Example.
    – alter igel
    Nov 20 at 2:12






  • 1




    Thank you for bringing the lack of clarity to my attention. I created a mini program that reproduces the same problem. SDL_GetError doesn't find any error which was part of the problem.
    – SorSorSor
    Nov 20 at 3:02










  • Thanks! This looks much better. I suspect that kingRect.x and kingRect.y are uninitialized and might have garbage values, which could place the target rectangle somewhere really far off screen. Try adding kingRect.x = 0; kingRect.y = 0; in your constructor
    – alter igel
    Nov 20 at 4:18








2




2




This isn't nearly enough code to tell where the bug is coming from. Are you checking return values from SDL functions and checking SDL_GetError() when something fails? Please edit your question to include information to reproduce the problem, and consider creating a Minimal, Complete, Verifiable Example.
– alter igel
Nov 20 at 2:12




This isn't nearly enough code to tell where the bug is coming from. Are you checking return values from SDL functions and checking SDL_GetError() when something fails? Please edit your question to include information to reproduce the problem, and consider creating a Minimal, Complete, Verifiable Example.
– alter igel
Nov 20 at 2:12




1




1




Thank you for bringing the lack of clarity to my attention. I created a mini program that reproduces the same problem. SDL_GetError doesn't find any error which was part of the problem.
– SorSorSor
Nov 20 at 3:02




Thank you for bringing the lack of clarity to my attention. I created a mini program that reproduces the same problem. SDL_GetError doesn't find any error which was part of the problem.
– SorSorSor
Nov 20 at 3:02












Thanks! This looks much better. I suspect that kingRect.x and kingRect.y are uninitialized and might have garbage values, which could place the target rectangle somewhere really far off screen. Try adding kingRect.x = 0; kingRect.y = 0; in your constructor
– alter igel
Nov 20 at 4:18




Thanks! This looks much better. I suspect that kingRect.x and kingRect.y are uninitialized and might have garbage values, which could place the target rectangle somewhere really far off screen. Try adding kingRect.x = 0; kingRect.y = 0; in your constructor
– alter igel
Nov 20 at 4:18












1 Answer
1






active

oldest

votes

















up vote
1
down vote



accepted










King BK{renderer}; field gets initialised before your Game::Game finishes and gets a chance to assign a renderer, so it gets NULL instead. NULL is not a valid renderer and can't create textures. If you would have checked for error you would have got Invalid renderer message. Also decent compiler with enabled warnings will tell something like warning: 'Game::renderer' is used uninitialized in this function [-Wuninitialized]; consider enabling better warning levels in your compiler.



Second thing is that you never called IMG_Init with required image formats you intend to load.



Third thing is that code is misformatted and wouldn't compile without modifications. I suggest testing code that you post as MCCVE for still being compilable and reproducing your problem (as MCCVE implies).






share|improve this answer





















  • Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
    – SorSorSor
    Nov 20 at 16:32











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1 Answer
1






active

oldest

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1 Answer
1






active

oldest

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active

oldest

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active

oldest

votes








up vote
1
down vote



accepted










King BK{renderer}; field gets initialised before your Game::Game finishes and gets a chance to assign a renderer, so it gets NULL instead. NULL is not a valid renderer and can't create textures. If you would have checked for error you would have got Invalid renderer message. Also decent compiler with enabled warnings will tell something like warning: 'Game::renderer' is used uninitialized in this function [-Wuninitialized]; consider enabling better warning levels in your compiler.



Second thing is that you never called IMG_Init with required image formats you intend to load.



Third thing is that code is misformatted and wouldn't compile without modifications. I suggest testing code that you post as MCCVE for still being compilable and reproducing your problem (as MCCVE implies).






share|improve this answer





















  • Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
    – SorSorSor
    Nov 20 at 16:32















up vote
1
down vote



accepted










King BK{renderer}; field gets initialised before your Game::Game finishes and gets a chance to assign a renderer, so it gets NULL instead. NULL is not a valid renderer and can't create textures. If you would have checked for error you would have got Invalid renderer message. Also decent compiler with enabled warnings will tell something like warning: 'Game::renderer' is used uninitialized in this function [-Wuninitialized]; consider enabling better warning levels in your compiler.



Second thing is that you never called IMG_Init with required image formats you intend to load.



Third thing is that code is misformatted and wouldn't compile without modifications. I suggest testing code that you post as MCCVE for still being compilable and reproducing your problem (as MCCVE implies).






share|improve this answer





















  • Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
    – SorSorSor
    Nov 20 at 16:32













up vote
1
down vote



accepted







up vote
1
down vote



accepted






King BK{renderer}; field gets initialised before your Game::Game finishes and gets a chance to assign a renderer, so it gets NULL instead. NULL is not a valid renderer and can't create textures. If you would have checked for error you would have got Invalid renderer message. Also decent compiler with enabled warnings will tell something like warning: 'Game::renderer' is used uninitialized in this function [-Wuninitialized]; consider enabling better warning levels in your compiler.



Second thing is that you never called IMG_Init with required image formats you intend to load.



Third thing is that code is misformatted and wouldn't compile without modifications. I suggest testing code that you post as MCCVE for still being compilable and reproducing your problem (as MCCVE implies).






share|improve this answer












King BK{renderer}; field gets initialised before your Game::Game finishes and gets a chance to assign a renderer, so it gets NULL instead. NULL is not a valid renderer and can't create textures. If you would have checked for error you would have got Invalid renderer message. Also decent compiler with enabled warnings will tell something like warning: 'Game::renderer' is used uninitialized in this function [-Wuninitialized]; consider enabling better warning levels in your compiler.



Second thing is that you never called IMG_Init with required image formats you intend to load.



Third thing is that code is misformatted and wouldn't compile without modifications. I suggest testing code that you post as MCCVE for still being compilable and reproducing your problem (as MCCVE implies).







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 20 at 4:26









keltar

12.2k12534




12.2k12534












  • Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
    – SorSorSor
    Nov 20 at 16:32


















  • Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
    – SorSorSor
    Nov 20 at 16:32
















Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
– SorSorSor
Nov 20 at 16:32




Thanks. It seems like there were two problems.The first is what you described in your first paragraph and the second was that even though I called IMG_LOAD with a path to the picture it wouldn't be loaded. So I moved the png right beside the actual code for this project and then it would load.
– SorSorSor
Nov 20 at 16:32


















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