C++, SDL2, OpenGL - Texture example

main.cpp

#include <SDL2/SDL_image.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>
#include <string>
using namespace std;

SDL_Window *window;
SDL_Event event;

SDL_Surface *texture;
GLuint textureID=0;

float x=0, y=0;

int mode=GL_RGB;

void loadTexture(string path){
    texture=IMG_Load(path.c_str());

    if(texture->format->BitsPerPixel>=4)
        mode=GL_RGBA;
    else
        mode=GL_RGB;

    glGenTextures(1, &textureID);
    glBindTexture(GL_TEXTURE_2D, textureID);

    glTexImage2D(GL_TEXTURE_2D, 0, mode, texture->w, texture->h, 0, 
                            mode, GL_UNSIGNED_BYTE, texture->pixels);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
}

void displayTexture(){
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    glTranslatef(x, y, 0);
    glBegin(GL_POLYGON);
        glTexCoord2f(0, 0); glVertex2i(0, 0);
        glTexCoord2f(1, 0); glVertex2i(texture->w, 0);
        glTexCoord2f(1, 1); glVertex2i(texture->w, texture->h);
        glTexCoord2f(0, 1); glVertex2i(0, texture->h);
    glEnd();

    glDisable(GL_BLEND);
    glDisable(GL_TEXTURE_2D);
}

int main(){
    window=SDL_CreateWindow("Window", SDL_WINDOWPOS_CENTERED, 
        SDL_WINDOWPOS_CENTERED, 800, 800, SDL_WINDOW_OPENGL);
        
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);

    SDL_GLContext glContext=SDL_GL_CreateContext(window);

    SDL_GL_SetSwapInterval(SDL_FALSE);

    loadTexture("1.png");

    while(window!=NULL){
        while(SDL_PollEvent(&event)){
            if(event.type==SDL_QUIT)
                window=NULL;
            if(event.key.keysym.scancode==SDL_SCANCODE_ESCAPE)
                window=NULL;
        }

        glClearColor(0, 0, 0, 0);
        glClear(GL_COLOR_BUFFER_BIT);

        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0, 800, 800, 0, -10, 10);

        displayTexture();

        SDL_GL_SwapWindow(window);
    }
}

hello, I have a class with these functions and I can draw 2 textures, but sometimes they are not drawn properly. Can you give me an example where you have 2 textures drawn?

hello, I have a class with these functions and I can draw 2 textures, but sometimes they are not drawn properly. Can you give me an example where you have 2 textures drawn?

https://gamedev.stackexchange.com/questions/46640/how-to-draw-2d-images-using-opengl-in-sdl

thanks but i used glPushMatrix() and glPopMatrix() and my problem was solved

thanks but i used glPushMatrix() and glPopMatrix() and my problem was solved

Ok, glad you solved that : 3