From bfed01435bebf8928a640c8645785816e48c6e38 Mon Sep 17 00:00:00 2001
From: chyyran <ronny@ronnychan.ca>
Date: Sat, 26 Nov 2022 16:58:23 -0500
Subject: [PATCH] gl: fix redundant fbo rebind

---
 librashader-runtime-gl/src/filter_chain.rs   | 9 +++++++--
 librashader-runtime-gl/src/filter_pass.rs    | 1 -
 librashader-runtime-gl/src/hello_triangle.rs | 1 -
 librashader-runtime-gl/src/lib.rs            | 2 +-
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/librashader-runtime-gl/src/filter_chain.rs b/librashader-runtime-gl/src/filter_chain.rs
index 26f4d94..b3254d8 100644
--- a/librashader-runtime-gl/src/filter_chain.rs
+++ b/librashader-runtime-gl/src/filter_chain.rs
@@ -593,6 +593,9 @@ impl FilterChain {
         Ok(())
     }
 
+    /// Process a frame with the input image.
+    ///
+    /// When this frame returns, GL_FRAMEBUFFER is bound to 0.
     pub fn frame(&mut self, count: usize, viewport: &Viewport, input: &GlImage, clear: bool) -> Result<()> {
         if clear {
             for framebuffer in &self.history_framebuffers {
@@ -605,7 +608,8 @@ impl FilterChain {
         }
 
         unsafe {
-            gl::BindFramebuffer(gl::FRAMEBUFFER, 0);
+            // do not need to rebind FBO 0 here since first `draw` will
+            // bind automatically.
             gl::BindVertexArray(self.filter_vao);
         }
 
@@ -719,8 +723,9 @@ impl FilterChain {
         }
 
         self.push_history(input)?;
+
+        // pass.draw should return framebuffer bound to 0.
         unsafe {
-            gl::BindFramebuffer(gl::FRAMEBUFFER, 0);
             gl::BindVertexArray(0);
         }
 
diff --git a/librashader-runtime-gl/src/filter_pass.rs b/librashader-runtime-gl/src/filter_pass.rs
index b257045..fca3b12 100644
--- a/librashader-runtime-gl/src/filter_pass.rs
+++ b/librashader-runtime-gl/src/filter_pass.rs
@@ -190,7 +190,6 @@ impl FilterPass {
         // todo: final pass?
 
         unsafe {
-            gl::BindFramebuffer(gl::FRAMEBUFFER, framebuffer.handle);
             gl::ColorMask(gl::TRUE, gl::TRUE, gl::TRUE, gl::TRUE);
             gl::ClearColor(0.0f32, 0.0f32, 0.0f32, 0.0f32);
             gl::Clear(gl::COLOR_BUFFER_BIT);
diff --git a/librashader-runtime-gl/src/hello_triangle.rs b/librashader-runtime-gl/src/hello_triangle.rs
index 69978d9..756b877 100644
--- a/librashader-runtime-gl/src/hello_triangle.rs
+++ b/librashader-runtime-gl/src/hello_triangle.rs
@@ -523,7 +523,6 @@ void main()
         unsafe {
             // texture is done now.
             // draw quad to screen
-            gl::BindFramebuffer(gl::FRAMEBUFFER, 0);
             gl::UseProgram(quad_programid);
 
             gl::ActiveTexture(gl::TEXTURE0);
diff --git a/librashader-runtime-gl/src/lib.rs b/librashader-runtime-gl/src/lib.rs
index d4a7054..b9e8837 100644
--- a/librashader-runtime-gl/src/lib.rs
+++ b/librashader-runtime-gl/src/lib.rs
@@ -27,7 +27,7 @@ mod tests {
     fn triangle_gl() {
         let (glfw, window, events, shader, vao) = hello_triangle::setup();
         let mut filter =
-            FilterChain::load_from_path("../test/slang-shaders/crt/crt-royale.slangp")
+            FilterChain::load_from_path("../test/slang-shaders/vhs/VHSPro.slangp")
                 .unwrap();
         hello_triangle::do_loop(glfw, window, events, shader, vao, &mut filter);
     }