From 9f5d740c11a0cdb596ce298a70898b901983e350 Mon Sep 17 00:00:00 2001
From: Eddie <hotstreams7@yandex.ru>
Date: Mon, 10 Jun 2024 16:36:26 +0300
Subject: [PATCH] terrain update

---
 include/limitless/core/indexed_stream.hpp |  1 +
 shaders/terrain/terrain.glsl              | 92 ++++++++++++++++++-----
 2 files changed, 76 insertions(+), 17 deletions(-)

diff --git a/include/limitless/core/indexed_stream.hpp b/include/limitless/core/indexed_stream.hpp
index b2925c32..dc3c4fff 100644
--- a/include/limitless/core/indexed_stream.hpp
+++ b/include/limitless/core/indexed_stream.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <limitless/core/vertex_stream.hpp>
+#include <algorithm>
 
 namespace Limitless {
     template <typename Vertex>
diff --git a/shaders/terrain/terrain.glsl b/shaders/terrain/terrain.glsl
index 841fbe29..fde83e2b 100644
--- a/shaders/terrain/terrain.glsl
+++ b/shaders/terrain/terrain.glsl
@@ -13,24 +13,82 @@ vec3 MacroContrast(float variation) {
     return mix(variation_contrast, vec3(1.0), vec3(variation));
 }
 
+#define _2xSqrt3 3.46410161514
+
+vec2 hashUv( vec2 p)
+{
+    return fract ( sin (( p ) * mat2 (127.1 , 311.7 , 269.5 , 183.3))
+                   *43758.5453) ;
+}
+
+void triangleGrid(vec2 uv,
+out float w1, out float w2, out float w3,
+out ivec2 v1, out ivec2 v2, out ivec2 v3)
+{
+    const mat2 skewedGridTransform = mat2(1.0, 0.0, -0.57735027, 1.15470054);
+    vec2 skewedUv = skewedGridTransform * uv * _2xSqrt3;
+
+    ivec2 vBase = ivec2(floor(skewedUv));
+    vec3 temp = vec3(fract(skewedUv), 0);
+    temp.z = 1.0 - temp.x - temp.y;
+    if (temp.z > 0.0) {
+        w1 = temp.z;
+        w2 = temp.y;
+        w3 = temp.x;
+        v1 = vBase;
+        v2 = vBase + ivec2(0, 1);
+        v3 = vBase + ivec2(1, 0);
+    } else {
+        w1 = -temp.z;
+        w2 = 1.0 - temp.y;
+        w3 = 1.0 - temp.x;
+        v1 = vBase + ivec2(1, 1);
+        v2 = vBase + ivec2(1, 0);
+        v3 = vBase + ivec2(0, 1);
+    }
+}
+
+vec3 StochasticTexture(vec2 uv, float index, sampler2DArray s)
+{
+    float w1 = 0, w2 = 0, w3 = 0;
+    ivec2 v1, v2, v3;
+    triangleGrid(uv, w1, w2, w3, v1, v2, v3);
+
+    vec2 uv1 = uv + hashUv(v1);
+    vec2 uv2 = uv + hashUv(v2);
+    vec2 uv3 = uv + hashUv(v3);
+
+    vec2 duvdx = dFdx(uv);
+    vec2 duvdy = dFdy(uv);
+
+    vec3 T1 = textureGrad(s, vec3(uv1, index), duvdx, duvdy).rgb;
+    vec3 T2 = textureGrad(s, vec3(uv2, index), duvdx, duvdy).rgb;
+    vec3 T3 = textureGrad(s, vec3(uv3, index), duvdx, duvdy).rgb;
+
+    vec3 col = w1 * T1 + w2 * T2 + w3 * T3;
+    return col;
+}
+
 void calculateTerrain(inout MaterialContext mctx) {
-    vec2 uv2 = getVertexUV1() * 4.0;
+    vec2 terrain_uv = (getVertexPosition().xz / 25.6) * 256.0;
+
     vec3 variation = MacroContrast(MacroVariation());
-    vec3 diffuse = texture(_terrain_diffuse_texture, vec3(uv2, getVertexTileCurrent())).rgb * vec3(1.0, 2.0, 1.0);
-    vec3 normal = texture(_terrain_normal_texture, vec3(uv2, getVertexTileCurrent())).xyz;
-    vec3 orm = texture(_terrain_orm_texture, vec3(uv2, getVertexTileCurrent())).rgb;
+
+    vec3 diffuse = StochasticTexture(terrain_uv, getVertexTileCurrent(), _terrain_diffuse_texture);
+    vec3 normal = StochasticTexture(terrain_uv, getVertexTileCurrent(), _terrain_normal_texture);
+    vec3 orm = StochasticTexture(terrain_uv, getVertexTileCurrent(), _terrain_orm_texture);
 
     vec2 uv = getVertexUV();
 
     float vectors[8] = {
-        smoothstep(0.0, 1.0, length(uv)),
-        smoothstep(0.0, 1.0, uv.y),
-        smoothstep(0.0, 1.0, length(vec2(1.0 - uv.x, uv.y))),
-        smoothstep(0.0, 1.0, uv.x),
-        smoothstep(0.0, 1.0, 1.0 - uv.x),
-        smoothstep(0.0, 1.0, length(vec2(uv.x, 1.0 - uv.y))),
-        smoothstep(0.0, 1.0, 1.0 - uv.y),
-        smoothstep(0.0, 1.0, length(vec2(1.0 - uv.x, 1.0 - uv.y)))
+    smoothstep(0.0, 1.0, length(uv)),
+    smoothstep(0.0, 1.0, uv.y),
+    smoothstep(0.0, 1.0, length(vec2(1.0 - uv.x, uv.y))),
+    smoothstep(0.0, 1.0, uv.x),
+    smoothstep(0.0, 1.0, 1.0 - uv.x),
+    smoothstep(0.0, 1.0, length(vec2(uv.x, 1.0 - uv.y))),
+    smoothstep(0.0, 1.0, 1.0 - uv.y),
+    smoothstep(0.0, 1.0, length(vec2(1.0 - uv.x, 1.0 - uv.y)))
     };
 
     uint mask[8];
@@ -44,9 +102,9 @@ void calculateTerrain(inout MaterialContext mctx) {
         // shoud we blend
         if (mask[i] == 1u) {
             // fetch adjacent type
-            vec3 adjacent_diffuse = texture(_terrain_diffuse_texture, vec3(uv2, types[i])).rgb;
-            vec3 adjacent_normal = texture(_terrain_normal_texture, vec3(uv2, types[i])).xyz;
-            vec3 adjacent_orm = texture(_terrain_orm_texture, vec3(uv2, types[i])).rgb;
+            vec3 adjacent_diffuse = StochasticTexture(terrain_uv, types[i], _terrain_diffuse_texture).rgb;
+            vec3 adjacent_normal = StochasticTexture(terrain_uv, types[i], _terrain_normal_texture).xyz;
+            vec3 adjacent_orm = StochasticTexture(terrain_uv, types[i], _terrain_orm_texture).rgb;
 
             // mix
             diffuse = mix(diffuse, adjacent_diffuse, (1.0 - vectors[i]));
@@ -55,12 +113,12 @@ void calculateTerrain(inout MaterialContext mctx) {
         }
     }
 
-    diffuse *= variation;
+//    diffuse *= variation;
 
     // store result
     mctx.color.rgb = diffuse;
     mctx.normal = normalize(normal);
     mctx.ao = orm.r;
     mctx.roughness = orm.g;
-    mctx.metallic =orm.b;
+    mctx.metallic = orm.b;
 }
\ No newline at end of file