Ensure OS windows have both buffers cleared after a resize/on first r…

…ender
kovidgoyal · Nov 24, 2017 · b61c959 · b61c959
1 parent c7e9082
commit b61c959
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Showing 4 changed files with 11 additions and 0 deletions.
diff --git a/kitty/child-monitor.c b/kitty/child-monitor.c
@@ -601,6 +601,7 @@ render(double now) {
         if (!w->num_tabs || !should_os_window_be_rendered(w)) continue;
         make_os_window_context_current(w);
         if (w->viewport_size_dirty) {
+            w->clear_count = 0;
             update_surface_size(w->viewport_width, w->viewport_height, w->offscreen_texture_id);
             w->viewport_size_dirty = false;
         }

diff --git a/kitty/gl.h b/kitty/gl.h
@@ -64,6 +64,7 @@ gl_init() {
 
 void
 update_surface_size(int w, int h, GLuint offscreen_texture_id) {
+    glViewport(0, 0, w, h);
     if (offscreen_texture_id) {
         glBindTexture(GL_TEXTURE_2D, offscreen_texture_id);
         glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

diff --git a/kitty/shaders.c b/kitty/shaders.c
@@ -365,6 +365,14 @@ draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, OSWind
 
 void 
 draw_cells(ssize_t vao_idx, ssize_t gvao_idx, GLfloat xstart, GLfloat ystart, GLfloat dx, GLfloat dy, Screen *screen, OSWindow *os_window) {
+    if (os_window->clear_count < 2) {
+        os_window->clear_count++;
+#define C(shift) (((GLfloat)((OPT(background) >> shift) & 0xFF)) / 255.0f)
+        glClearColor(C(16), C(8), C(0), os_window->is_semi_transparent ? OPT(background_opacity) : 1.0f);
+#undef C
+        glClear(GL_COLOR_BUFFER_BIT);
+    }
+
     cell_prepare_to_render(vao_idx, gvao_idx, screen, xstart, ystart, dx, dy);
     GLfloat w = (GLfloat)screen->columns * dx, h = (GLfloat)screen->lines * dy;
 #define SCALE(w, x) ((GLfloat)(os_window->viewport_##w) * (GLfloat)(x))

diff --git a/kitty/state.h b/kitty/state.h
@@ -104,6 +104,7 @@ typedef struct {
     bool has_pending_resizes;
     bool is_semi_transparent;
     uint32_t offscreen_texture_id;
+    unsigned int clear_count;
 } OSWindow;