From 2b4a7d868112b4995bf6699f5b3aa68e9ec2b308 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Tue, 2 Oct 2012 13:59:31 +0200
Subject: [PATCH 1/1] Move calculation of normalized position for the vignette
 into the vertex shader.

---
 vignette_effect.cpp  | 5 +++++
 vignette_effect.frag | 5 ++---
 vignette_effect.h    | 1 +
 vignette_effect.vert | 9 +++++++++
 4 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 vignette_effect.vert

diff --git a/vignette_effect.cpp b/vignette_effect.cpp
index f1449ae..e140310 100644
--- a/vignette_effect.cpp
+++ b/vignette_effect.cpp
@@ -17,6 +17,11 @@ VignetteEffect::VignetteEffect()
 	register_float("inner_radius", (float *)&inner_radius);
 }
 
+std::string VignetteEffect::output_vertex_shader()
+{
+	return read_file("vignette_effect.vert");
+}
+
 std::string VignetteEffect::output_fragment_shader()
 {
 	return read_file("vignette_effect.frag");
diff --git a/vignette_effect.frag b/vignette_effect.frag
index bc84516..c7e1d61 100644
--- a/vignette_effect.frag
+++ b/vignette_effect.frag
@@ -1,15 +1,14 @@
 // A simple, circular vignette, with a cos² falloff.
 	
 uniform float PREFIX(inv_radius);
-uniform vec2 PREFIX(aspect_correction);
+varying vec2 PREFIX(normalized_pos);
 
 vec4 FUNCNAME(vec2 tc) {
 	vec4 x = LAST_INPUT(tc);
 
 	const float pihalf = 0.5 * 3.14159265358979324;
 
-	vec2 normalized_pos = (tc - PREFIX(center)) * PREFIX(aspect_correction);
-	float dist = (length(normalized_pos) - PREFIX(inner_radius)) * PREFIX(inv_radius);
+	float dist = (length(PREFIX(normalized_pos)) - PREFIX(inner_radius)) * PREFIX(inv_radius);
 	float linear_falloff = clamp(dist, 0.0, 1.0) * pihalf;
 	float falloff = cos(linear_falloff) * cos(linear_falloff);
 	x.rgb *= vec3(falloff);
diff --git a/vignette_effect.h b/vignette_effect.h
index b8e0f68..1d75f7e 100644
--- a/vignette_effect.h
+++ b/vignette_effect.h
@@ -6,6 +6,7 @@
 class VignetteEffect : public Effect {
 public:
 	VignetteEffect();
+	std::string output_vertex_shader();
 	std::string output_fragment_shader();
 
 	void set_uniforms(GLuint glsl_program_num, const std::string &prefix);
diff --git a/vignette_effect.vert b/vignette_effect.vert
new file mode 100644
index 0000000..44edeb8
--- /dev/null
+++ b/vignette_effect.vert
@@ -0,0 +1,9 @@
+uniform vec2 PREFIX(aspect_correction);
+varying vec2 PREFIX(normalized_pos);
+
+vec2 FUNCNAME()
+{
+	vec2 temp = LAST_INPUT();
+	PREFIX(normalized_pos) = (temp - PREFIX(center)) * PREFIX(aspect_correction);
+	return temp;
+}
-- 
2.39.2