From f4516cf70e80bf1153759919c8b2ab1cee37d9ec Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Tue, 2 Oct 2012 00:45:55 +0200
Subject: [PATCH] Add a vignette effect.

---
 Makefile             |  2 +-
 effect_chain.cpp     |  3 +++
 effect_id.h          |  3 +++
 vignette_effect.cpp  | 33 +++++++++++++++++++++++++++++++++
 vignette_effect.glsl | 18 ++++++++++++++++++
 vignette_effect.h    | 18 ++++++++++++++++++
 6 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 vignette_effect.cpp
 create mode 100644 vignette_effect.glsl
 create mode 100644 vignette_effect.h

diff --git a/Makefile b/Makefile
index b61f78b..11482ba 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ CXX=g++
 CXXFLAGS=-Wall -g
 LDFLAGS=-lSDL -lSDL_image -lGL
 OBJS=main.o util.o widgets.o effect.o effect_chain.o
-OBJS += lift_gamma_gain_effect.o gamma_expansion_effect.o gamma_compression_effect.o colorspace_conversion_effect.o saturation_effect.o
+OBJS += lift_gamma_gain_effect.o gamma_expansion_effect.o gamma_compression_effect.o colorspace_conversion_effect.o saturation_effect.o vignette_effect.o
 
 test: $(OBJS)
 	$(CXX) -o test $(OBJS) $(LDFLAGS)
diff --git a/effect_chain.cpp b/effect_chain.cpp
index a15a566..623d64a 100644
--- a/effect_chain.cpp
+++ b/effect_chain.cpp
@@ -14,6 +14,7 @@
 #include "lift_gamma_gain_effect.h"
 #include "colorspace_conversion_effect.h"
 #include "saturation_effect.h"
+#include "vignette_effect.h"
 #include "texture_enum.h"
 
 EffectChain::EffectChain(unsigned width, unsigned height)
@@ -44,6 +45,8 @@ Effect *instantiate_effect(EffectId effect)
 		return new LiftGammaGainEffect();
 	case EFFECT_SATURATION:
 		return new SaturationEffect();
+	case EFFECT_VIGNETTE:
+		return new VignetteEffect();
 	}
 	assert(false);
 }
diff --git a/effect_id.h b/effect_id.h
index 623bb39..644393d 100644
--- a/effect_id.h
+++ b/effect_id.h
@@ -10,6 +10,9 @@ enum EffectId {
        // Color.
        EFFECT_LIFT_GAMMA_GAIN,
        EFFECT_SATURATION,
+
+       // Spatial.
+       EFFECT_VIGNETTE,
 };
 
 #endif // !defined(_EFFECT_ID_H)
diff --git a/vignette_effect.cpp b/vignette_effect.cpp
new file mode 100644
index 0000000..08dadab
--- /dev/null
+++ b/vignette_effect.cpp
@@ -0,0 +1,33 @@
+#define GL_GLEXT_PROTOTYPES 1
+
+#include <math.h>
+#include <GL/gl.h>
+#include <GL/glext.h>
+
+#include "vignette_effect.h"
+#include "util.h"
+
+VignetteEffect::VignetteEffect()
+	: center(0.5f, 0.5f),
+	  radius(0.3f),
+	  inner_radius(0.3f)
+{
+	register_vec2("center", (float *)&center);
+	register_float("radius", (float *)&radius);
+	register_float("inner_radius", (float *)&inner_radius);
+}
+
+std::string VignetteEffect::output_glsl()
+{
+	return read_file("vignette_effect.glsl");
+}
+
+void VignetteEffect::set_uniforms(GLhandleARB glsl_program_num, const std::string &prefix)
+{
+	Effect::set_uniforms(glsl_program_num, prefix);
+
+	set_uniform_float(glsl_program_num, prefix, "inv_radius", 1.0f / radius);
+
+	Point2D aspect(16.0f / 9.0f, 1.0f);  // FIXME
+	set_uniform_vec2(glsl_program_num, prefix, "aspect_correction", (float *)&aspect);
+}
diff --git a/vignette_effect.glsl b/vignette_effect.glsl
new file mode 100644
index 0000000..4e4f26b
--- /dev/null
+++ b/vignette_effect.glsl
@@ -0,0 +1,18 @@
+// A simple, circular vignette, with a cos² falloff.
+	
+uniform float PREFIX(inv_radius);
+uniform vec2 PREFIX(aspect_correction);
+
+vec4 FUNCNAME(vec2 tc) {
+	vec4 x = LAST_INPUT(tc);
+
+	const float pihalf = 3.14159265358979324 / 2;
+
+	vec2 normalized_pos = (tc - PREFIX(center)) * PREFIX(aspect_correction);
+	float dist = (length(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);
+
+	return x;
+}
diff --git a/vignette_effect.h b/vignette_effect.h
new file mode 100644
index 0000000..6caff36
--- /dev/null
+++ b/vignette_effect.h
@@ -0,0 +1,18 @@
+#ifndef _VIGNETTE_EFFECT_H
+#define _VIGNETTE_EFFECT_H 1
+
+#include "effect.h"
+
+class VignetteEffect : public Effect {
+public:
+	VignetteEffect();
+	std::string output_glsl();
+
+	void set_uniforms(GLhandleARB glsl_program_num, const std::string &prefix);
+
+private:
+	Point2D center;
+	float radius, inner_radius;
+};
+
+#endif // !defined(_VIGNETTE_EFFECT_H)
-- 
2.39.2