SDL2 fails to create opengl window in wasm64 builds #20273
Description
SDL2 fails to create an opengl window with error message "Could not create GLES window surface"
Reproducible code:
#include "SDL.h"
#include <emscripten.h>
#include <webgl/webgl2.h>
#include <stdio.h>
#include <string.h>
#define WIDTH 640
#define HEIGHT 480
void onDraw(void *arg) {
SDL_Window *window = *((SDL_Window **)arg);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 3);
SDL_GL_SwapWindow(window);
}
int main(int argc, char *argv[]) {
int res = SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER);
if (res) {
fprintf(stderr, "Error initializing SDL %s", SDL_GetError());
}
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 0);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
SDL_Window *window = SDL_CreateWindow("OpenGL Window", SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED, WIDTH, HEIGHT,
SDL_WINDOW_OPENGL);
if (!window) {
fprintf(stderr, "Couldn't create window: %s\n", SDL_GetError());
return 0;
}
SDL_SetWindowResizable(window, SDL_TRUE);
SDL_GLContext context = SDL_GL_CreateContext(window);
if (!context) {
fprintf(stderr, "Couldn't create context: %s\n", SDL_GetError());
return 0;
}
GLuint vertex_shader;
GLuint fragment_shader;
GLuint program;
{
const GLchar *source = "attribute vec4 apos;"
"attribute vec4 acolor;"
"varying vec4 color;"
"void main() {"
"color = acolor;"
"gl_Position = apos;"
"}";
vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &source, NULL);
glCompileShader(vertex_shader);
}
{
const GLchar *source = "precision lowp float;"
"varying vec4 color;"
"void main() {"
"gl_FragColor = color;"
"}";
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &source, NULL);
glCompileShader(fragment_shader);
}
program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
glUseProgram(program);
// clang-format off
const float pos_and_color[] = {
// x, y, r, g, b
-0.6f, -0.6f, 1, 0, 0,
0.6f, -0.6f, 0, 1, 0,
0.f, 0.6f, 0, 0, 1,
};
// clang-format on
GLuint vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(pos_and_color), pos_and_color,
GL_STATIC_DRAW);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 20, 0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 20, (void *)8);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
emscripten_set_main_loop_arg(onDraw, &window, 0, 1);
}32-bit works.
$ emcc main.c -o index.html -sUSE_SDL=2 -sUSE_WEBGL2
$ python3 -m http.server 
64-bit doesn't work
$ emcc main.c -o index.html -sMEMORY64=1 -sMAXIMUM_MEMORY=6GB -sALLOW_MEMORY_GROWTH -sWASM_BIGINT=1 -sUSE_SDL=2 -sUSE_WEBGL2
$ python3 -m http.server 
Version of emscripten/emsdk:
emcc --version
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.46-git (7c7321c265c47d54dacdd25d00c2c3c9ec2a8425)
Copyright (C) 2014 the Emscripten authors (see AUTHORS.txt)
This is free and open source software under the MIT license.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.Version of browser:
Chromium Version 119.0.6011.0 (Developer Build) custom (64-bit)