Here’s a test case to demonstrate the issue. It should draw a white square on a blue background, with all four corner pixels drawn, and this is what happens in Windows and Mac OS. But in Linux (Ubuntu 16.04, SDL 2.0.4) it draws only two horizontal lines. Can somebody confirm this, or if they find it is working correctly report on what version of Linux/OpenGL/SDL they are using:
Code:
// Demo of SDL_RenderDrawLine endpoint behavior, R.T.Russell http://www.rtrussell.co.uk/
#include <stdio.h>
#include “SDL2_gfxPrimitives.h”
#define WIDTH 640
#define HEIGHT 480
int main(int argc, char* argv[])
{
if (SDL_Init(SDL_INIT_VIDEO))
{
printf ("SDL_Init Error: %s", SDL_GetError());
return 1;
}
SDL_SetHint (SDL_HINT_RENDER_DRIVER, "opengl") ;
SDL_Window *window = SDL_CreateWindow("SDL_RenderDrawLine test", 100, 100, WIDTH, HEIGHT, SDL_WINDOW_OPENGL);
if (window == NULL)
{
printf ("SDL_CreateWindow Error: %s", SDL_GetError());
SDL_Quit();
return 2;
}
SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
if (renderer == NULL)
{
SDL_DestroyWindow(window);
printf ("SDL_CreateRenderer Error: %s", SDL_GetError());
SDL_Quit();
return 3;
}
SDL_Event e;
int quit = 0;
while (!quit)
{
int i;
int w = WIDTH / 4;
int h = w;
int x = (WIDTH - w) / 2;
int y = (HEIGHT - h) / 2;
if (SDL_PollEvent(&e))
{
if (e.type == SDL_QUIT)
quit = 1;
}
SDL_SetRenderDrawColor(renderer, 0, 0, 0xFF, 0xFF);
SDL_RenderClear(renderer);
SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);
SDL_RenderDrawLine(renderer, x, y, x + w, y);
SDL_RenderDrawLine(renderer, x, y + h, x + w, y + h);
for (i = y + 1; i < y + h; i++)
{
SDL_RenderDrawLine(renderer, x, i, x, i) ;
SDL_RenderDrawLine(renderer, x + w, i, x + w, i);
}
SDL_RenderPresent(renderer);
SDL_Delay(10);
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
Richard.
