From 6922b3ef322b2bc704d615889601596aa41d6b87 Mon Sep 17 00:00:00 2001
From: hyzboy <hyzboy@gmail.com>
Date: Wed, 15 Jul 2020 19:18:28 +0800
Subject: [PATCH] add EndlessGrid.frag

---
 shader/EndlessGrid.frag | 65 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 shader/EndlessGrid.frag

diff --git a/shader/EndlessGrid.frag b/shader/EndlessGrid.frag
new file mode 100644
index 0000000..48e9201
--- /dev/null
+++ b/shader/EndlessGrid.frag
@@ -0,0 +1,65 @@
+#version 450 core
+
+layout(location=0) out vec4 FragColor;
+
+layout(binding=1) uniform ColorMaterial
+{
+    vec4 color;
+} color_material;
+
+layout(binding=10) uniform WorldMatrix     // hgl/math/Math.h
+{
+    mat4 ortho;
+
+    mat4 projection;
+    mat4 inverse_projection;
+
+    mat4 modelview;
+    mat4 inverse_modelview;
+
+    mat4 mvp;
+    mat4 inverse_mvp;
+
+    vec4 view_pos;
+    vec2 canvas_resolution;
+    vec2 viewport_resolution;
+}fs_world;
+
+const float TAU = 2.* 3.1415926535897932384626433832795;
+const float grid4 = 2097152.0,grid3 = 131072.0,grid2 = 1024.0,grid1 = 64.0;
+
+float grid(vec2 f, vec3 pos, float rdy, float t) {
+    float ff = min(fs_world.canvas_resolution.x,fs_world.canvas_resolution.y)/1024.0;
+	vec4 distances = (abs(pos.xz)* TAU).xxyy;
+	float referenceBase = log(20.*ff/ (t* pow(abs(rdy),.8)))/ log(10.);
+	float nearestBase = floor(referenceBase);
+	float partialBase = fract(referenceBase);
+	const vec4 gain = vec4(grid4- grid3,grid1,grid3- grid2,grid2- grid1);
+	const vec4 off = vec4(grid3,0,grid2,grid1);
+	vec4 exponentialBase = partialBase* partialBase* gain+ off;
+	vec4 bases = pow(vec4(10),nearestBase+ vec4(-2,1,-1,0));
+	vec4 lx = pow(.5+ .5* cos(distances* bases.xyxy),exponentialBase.xyxy);
+	vec4 ly = pow(.5+ .5* cos(distances* bases.zwzw),exponentialBase.zwzw);
+	vec4 l4 = (1.- lx* vec4(1.- partialBase,partialBase,1.- partialBase,partialBase))* (1.- ly);
+	vec2 l2 = l4.xy* l4.zw;
+	float l1 = .30078125* (1.- l2.x* l2.y);
+	return l1;
+}
+
+float EndlessGird(vec2 f)
+{
+	float rcpResY = 1./ fs_world.canvas_resolution.y;
+	vec2 uv = 2.0* rcpResY* f- vec2(fs_world.canvas_resolution.x* rcpResY,1);
+	vec3 ro = vec3(0,1.0,0);
+	vec3 rd = normalize(vec3(uv.x,-1,uv.y));
+	float t = 1.0/ -rd.y;
+	vec3 pos = ro + t* rd;
+	return grid(f,pos,rd.y,t);
+}
+
+void main()
+{
+    float strong=EndlessGird(gl_FragCoord.xy);
+
+    FragColor=vec4(color_material.color.rgb*strong,1.0);
+}