From 5e2587920ab276788c2f32414277207cbaaa8402 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 24 Nov 2017 00:16:37 +0530
Subject: [PATCH] Call glViewport in the render loop

Ensure FBOs have correct viewport
---
 kitty/gl.h      | 1 -
 kitty/shaders.c | 4 ++++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/kitty/gl.h b/kitty/gl.h
index b68c4c683..1ba0821bb 100644
--- a/kitty/gl.h
+++ b/kitty/gl.h
@@ -64,7 +64,6 @@ 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
index 081617d9d..35867931e 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -326,9 +326,11 @@ draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, OSWind
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); 
     }
+    glBindTexture(GL_TEXTURE_2D, 0);
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, offscreen_framebuffer);
     glFramebufferTexture(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, os_window->offscreen_texture_id, 0);
     /* if (glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) fatal("offscreen framebuffer not complete"); */
+    glViewport(0, 0, os_window->viewport_width, os_window->viewport_height);
 
     bind_program(CELL_BG_PROGRAM); 
     glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, screen->lines * screen->columns); 
@@ -347,6 +349,7 @@ draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, OSWind
 
     glDisable(GL_BLEND);
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+    glViewport(0, 0, os_window->viewport_width, os_window->viewport_height);
 
     // Now render the framebuffer to the screen reversing alpha pre-multiplication
     glEnable(GL_SCISSOR_TEST);
@@ -374,6 +377,7 @@ draw_cells(ssize_t vao_idx, ssize_t gvao_idx, GLfloat xstart, GLfloat ystart, GL
             (GLsizei)(ceilf(SCALE(height, h / 2.0f)))
     );
 #undef SCALE
+    glViewport(0, 0, os_window->viewport_width, os_window->viewport_height);
     static bool cell_constants_set = false;
     if (!cell_constants_set) { 
         bind_program(CELL_PROGRAM);