From 14e3617736c63bd22b0785ad418acef825db221f Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Thu, 28 Oct 2021 17:10:41 +0200
Subject: Use a separate glx context for every window

Fix vertex buffer causing crash on render if update is called with an
empty list.
---
 src/graphics/vertex_buffer.c | 15 ++++++++++++++-
 src/mgl.c                    | 11 -----------
 src/window/window.c          | 16 ++++++++++++++--
 3 files changed, 28 insertions(+), 14 deletions(-)

(limited to 'src')

diff --git a/src/graphics/vertex_buffer.c b/src/graphics/vertex_buffer.c
index 1f122c3..aa4fdbb 100644
--- a/src/graphics/vertex_buffer.c
+++ b/src/graphics/vertex_buffer.c
@@ -56,6 +56,7 @@ static int mgl_vertex_buffer_resize(mgl_vertex_buffer *self, const mgl_vertex *v
     self->usage = usage;
 
     context->gl.glBindBuffer(GL_ARRAY_BUFFER, self->id);
+    /* TODO: Optimize by calling with NULL data first? or do that in |mgl_vertex_buffer_update| */
     context->gl.glBufferData(GL_ARRAY_BUFFER, sizeof(mgl_vertex) * vertex_count, vertices, mgl_vertex_buffer_usage_to_gl_usage(self->usage));
     mgl_vertex_buffer_set_gl_buffer_pointers(context);
     context->gl.glBindBuffer(GL_ARRAY_BUFFER, 0);
@@ -69,10 +70,22 @@ void mgl_vertex_buffer_set_position(mgl_vertex_buffer *self, mgl_vec2f position)
 
 /* TODO: Check for glBufferSubData error */
 int mgl_vertex_buffer_update(mgl_vertex_buffer *self, const mgl_vertex *vertices, size_t vertex_count, mgl_primitive_type primitive_type, mgl_vertex_buffer_usage usage) {
+    mgl_context *context = mgl_get_context();
+    
+    if(vertex_count == 0) {
+        if(self->id) {
+            context->gl.glDeleteBuffers(1, &self->id);
+            self->id = 0;
+        }
+        self->vertex_count = vertex_count;
+        self->primitive_type = primitive_type;
+        self->usage = usage;
+        return 0;
+    }
+    
     if(vertex_count != self->vertex_count || primitive_type != self->primitive_type || usage != self->usage)
         return mgl_vertex_buffer_resize(self, vertices, vertex_count, primitive_type, usage);
 
-    mgl_context *context = mgl_get_context();
     context->gl.glBindBuffer(GL_ARRAY_BUFFER, self->id);
     context->gl.glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(mgl_vertex) * vertex_count, vertices);
     mgl_vertex_buffer_set_gl_buffer_pointers(context);
diff --git a/src/mgl.c b/src/mgl.c
index 549121f..6407d9e 100644
--- a/src/mgl.c
+++ b/src/mgl.c
@@ -39,21 +39,10 @@ static int glx_context_init() {
         return -1;
     }
 
-    context.glx_context = context.gl.glXCreateContext(context.connection, context.visual_info, NULL, 1);
-    if(!context.glx_context) {
-        fprintf(stderr, "glXCreateContext failed\n");
-        return -1;
-    }
-
     return 0;
 }
 
 static void glx_context_deinit() {
-    if(context.glx_context) {
-        context.gl.glXDestroyContext(context.connection, context.glx_context);
-        context.glx_context = NULL;
-    }
-
     if(context.visual_info) {
         XFree(context.visual_info);
         context.visual_info = NULL;
diff --git a/src/window/window.c b/src/window/window.c
index 2e9a1ba..f29b920 100644
--- a/src/window/window.c
+++ b/src/window/window.c
@@ -49,6 +49,12 @@ static int mgl_window_init(mgl_window *self, const char *title, int width, int h
     if(parent_window == 0)
         parent_window = DefaultRootWindow(context->connection);
 
+    self->glx_context = context->gl.glXCreateContext(context->connection, context->visual_info, NULL, 1);
+    if(!self->glx_context) {
+        fprintf(stderr, "glXCreateContext failed\n");
+        return -1;
+    }
+
     Colormap color_map = XCreateColormap(context->connection, DefaultRootWindow(context->connection), ((XVisualInfo*)context->visual_info)->visual, AllocNone);
     if(!color_map) {
         fprintf(stderr, "XCreateColormap failed\n");
@@ -68,6 +74,7 @@ static int mgl_window_init(mgl_window *self, const char *title, int width, int h
         if(!XChangeWindowAttributes(context->connection, existing_window, CWColormap | CWEventMask | CWBitGravity, &window_attr)) {
             fprintf(stderr, "XChangeWindowAttributes failed\n");
             XFreeColormap(context->connection, color_map);
+            mgl_window_deinit(self);
             return -1;
         }
         XFreeColormap(context->connection, color_map);
@@ -89,8 +96,8 @@ static int mgl_window_init(mgl_window *self, const char *title, int width, int h
 
     XFlush(context->connection);
 
-    /* TODO: Switch current when rendering to another window, and set current to NULL when destroying the currently selected context */
-    context->gl.glXMakeCurrent(context->connection, self->window, context->glx_context);
+    /* TODO: Check for failure? */
+    context->gl.glXMakeCurrent(context->connection, self->window, self->glx_context);
     set_vertical_sync_enabled(self->window, 1);
     context->gl.glEnable(GL_TEXTURE_2D);
     context->gl.glEnable(GL_BLEND);
@@ -123,6 +130,10 @@ int mgl_window_init_from_existing_window(mgl_window *self, mgl_window_handle exi
 
 void mgl_window_deinit(mgl_window *self) {
     mgl_context *context = mgl_get_context();
+    if(self->glx_context) {
+        context->gl.glXDestroyContext(context->connection, self->glx_context);
+        self->glx_context = NULL;
+    }
     if(self->window) {
         XDestroyWindow(context->connection, self->window);
         self->window = 0;
@@ -172,3 +183,4 @@ void mgl_window_display(mgl_window *self) {
     mgl_context *context = mgl_get_context();
     context->gl.glXSwapBuffers(context->connection, self->window);
 }
+
-- 
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