diff -r 5a8c31904e44 -r b3da4096c607 src/glcontext.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/glcontext.c	Tue Mar 26 20:37:21 2024 +0100
@@ -0,0 +1,111 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ * Copyright 2023 Mike Becker. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "ascension/glcontext.h"
+#include "ascension/error.h"
+
+#include <cx/printf.h>
+
+#include <GL/glew.h>
+
+static void asc_gl_debug_callback(
+        GLenum source, GLenum type, GLuint id, GLenum severity,
+        GLsizei length, const GLchar* message,
+        const void* userParam
+) {
+    cxmutstr buf = cx_asprintf(
+            "source = %d, id = %u, type = %d, severity= %d, message = %.*s",
+            source, id, type, severity, length, message);
+    if (type == GL_DEBUG_TYPE_ERROR) {
+        asc_error(buf.ptr);
+    } else {
+        asc_dprintf("GL debug: %.*s", (int)buf.length, buf.ptr);
+    }
+    cx_strfree(&buf);
+}
+
+static void asc_shader_initialize_predefined(AscGLContext *ctx) {
+    AscShaderSprite *sprite = &ctx->shader.sprite;
+    sprite->base = asc_shader_easy_compile_and_link("shader/sprite_vtx.glsl", "shader/sprite_frag.glsl");
+    sprite->surface = glGetUniformLocation(sprite->base.id, "surface");
+    sprite->depth = glGetUniformLocation(sprite->base.id, "depth");
+}
+
+static void asc_shader_destroy_predefined(AscGLContext *ctx) {
+    asc_shader_program_destroy(ctx->shader.sprite.base);
+}
+
+bool asc_gl_context_initialize(
+        AscGLContext *ctx,
+        SDL_Window *window,
+        AscGLContextSettings const *settings
+) {
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, settings->gl_major_version);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, settings->gl_minor_version);
+    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, settings->depth_size);
+    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+    ctx->glctx = SDL_GL_CreateContext(window);
+    if (ctx->glctx == NULL) return false;
+    ctx->window = window;
+
+    glewExperimental = GL_TRUE;
+    GLenum err = glewInit();
+    if (err == GLEW_OK) {
+        SDL_GL_SetSwapInterval(settings->vsync);
+
+        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+        glEnable(GL_DEBUG_OUTPUT);
+        glDebugMessageCallback(asc_gl_debug_callback, NULL);
+
+        if (!asc_primitives_init(&ctx->primitives)) {
+            asc_error("Creating primitive meshes failed");
+            SDL_GL_DeleteContext(ctx->glctx);
+            return false;
+        }
+
+        asc_shader_initialize_predefined(ctx);
+
+        return true;
+    } else {
+        asc_error(glewGetErrorString(err));
+        SDL_GL_DeleteContext(ctx->glctx);
+        return false;
+    }
+}
+
+void asc_gl_context_destroy(AscGLContext *ctx) {
+    if (ctx->glctx == NULL) return;
+    SDL_GL_MakeCurrent(ctx->window, ctx->glctx);
+
+    asc_shader_destroy_predefined(ctx);
+    asc_primitives_destroy(&ctx->primitives);
+
+    // destroy the GL context and the window
+    SDL_GL_DeleteContext(ctx->glctx);
+    ctx->glctx = NULL;
+}