From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 6 May 2021 10:15:40 +0000 (+0300)
Subject: Put the PI constant in builtins
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=9208e0ff263a287e456e082a4a8b8fd0bbd41f9e

Put the PI constant in builtins

It's needed in several places so this is easier than defining it
separately everywhere.
---

diff --git a/builtin_data/_builtin.glsl b/builtin_data/_builtin.glsl
index c8336d9a..1bdfde13 100644
--- a/builtin_data/_builtin.glsl
+++ b/builtin_data/_builtin.glsl
@@ -40,6 +40,8 @@ typedef image(dimensions=2[], shadow, sampled) float sampler2DArrayShadow;
 typedef image(dimensions=cube, shadow, sampled) float samplerCubeShadow;
 typedef image(dimensions=cube[], shadow, sampled) float samplerCubeArrayShadow;
 
+const float PI = 3.1415926535;
+
 // BEGIN BUILTIN FUNCTIONS
 float radians(float degrees);
 vec2 radians(vec2 degrees);
diff --git a/builtin_data/_pbr_prefilter.glsl b/builtin_data/_pbr_prefilter.glsl
index 1fcdd716..e0616c25 100644
--- a/builtin_data/_pbr_prefilter.glsl
+++ b/builtin_data/_pbr_prefilter.glsl
@@ -6,8 +6,6 @@ uniform PrecalcParams
 
 uniform samplerCube environment_map;
 
-const float PI = 3.1415926535;
-
 vec2 hammersley(int i, int count)
 {
 	float y = bitfieldReverse(uint(i))*2.3283064e-10;
diff --git a/builtin_data/_sky.glsl b/builtin_data/_sky.glsl
index 45ca330d..3493b5a4 100644
--- a/builtin_data/_sky.glsl
+++ b/builtin_data/_sky.glsl
@@ -32,7 +32,6 @@ struct OpticalPathInfo
 	vec3 luminance;
 };
 
-const float pi = 3.1415926535;
 const float mie_asymmetry = 0.8;
 
 uniform sampler2D transmittance_lookup;
@@ -44,7 +43,7 @@ vec3 rayleigh_density(vec3 base, float height)
 
 float rayleigh_phase(float cos_theta)
 {
-	return 3.0*(1.0+cos_theta*cos_theta)/(16.0*pi);
+	return 3.0*(1.0+cos_theta*cos_theta)/(16.0*PI);
 }
 
 vec3 mie_density(vec3 base, float height)
@@ -57,7 +56,7 @@ float mie_phase(float cos_theta)
 	float g = mie_asymmetry;
 	float num = (1.0-g*g)*(1.0+cos_theta*cos_theta);
 	float denom = (2.0+g*g)*pow(1.0+g*g-2.0*g*cos_theta, 1.5);
-	return 3.0/(8.0*pi)*num/denom;
+	return 3.0/(8.0*PI)*num/denom;
 }
 
 vec3 ozone_density(vec3 base, float height)
@@ -127,7 +126,7 @@ OpticalPathInfo raymarch_path(float start_height, vec3 look_dir)
 		vec3 in_transmittance = texture(transmittance_lookup, vec2(sqrt(height/atmosphere_thickness), light_z)).rgb;
 		vec3 in_luminance = (ev.rayleigh_scatter*p_rayleigh+ev.mie_scatter*p_mie)*step_size;
 		if(i==n_steps && ground_t>0.0)
-			in_luminance += ground_albedo*light_z/pi;
+			in_luminance += ground_albedo*light_z/PI;
 		path_luminance += transmittance*in_transmittance*in_luminance;
 
 		path_extinction += total_extinction(ev)*step_size;
diff --git a/builtin_data/_sky_backdrop.glsl b/builtin_data/_sky_backdrop.glsl
index 8d9f4ab9..420f0ed5 100644
--- a/builtin_data/_sky_backdrop.glsl
+++ b/builtin_data/_sky_backdrop.glsl
@@ -18,5 +18,5 @@ void main()
 {
 	vec3 nview = normalize(view_dir.xyz);
 	float azimuth = atan(nview.y, nview.x);
-	frag_color = texture(distant, vec2(azimuth/(2*pi), nview.z*0.5+0.5))*light_color;
+	frag_color = texture(distant, vec2(azimuth/(2*PI), nview.z*0.5+0.5))*light_color;
 }
diff --git a/builtin_data/_sky_distant.glsl b/builtin_data/_sky_distant.glsl
index 0680b986..e6d4800b 100644
--- a/builtin_data/_sky_distant.glsl
+++ b/builtin_data/_sky_distant.glsl
@@ -5,7 +5,7 @@ import _sky;
 layout(location=0) out vec3 frag_color;
 void main()
 {
-	float azimuth = texcoord.x*2.0*pi;
+	float azimuth = texcoord.x*2.0*PI;
 	float z = texcoord.y*2.0-1.0;
 	float r = sqrt(1.0-z*z);
 	vec3 look_dir = vec3(cos(azimuth)*r, sin(azimuth)*r, z);
diff --git a/shaderlib/cooktorrance.glsl b/shaderlib/cooktorrance.glsl
index 71f8ec76..4b0c4dc8 100644
--- a/shaderlib/cooktorrance.glsl
+++ b/shaderlib/cooktorrance.glsl
@@ -30,8 +30,6 @@ layout(constant_id=auto) const bool use_emission = false;
 layout(constant_id=auto) const bool use_emission_map = false;
 layout(constant_id=auto) const bool use_image_based_lighting = false;
 
-const float PI = 3.1415926535;
-
 #pragma MSP stage(fragment)
 virtual vec4 get_base_color()
 {