From 75fa5ce704285bb8bed2efd2de30d623e9905883 Mon Sep 17 00:00:00 2001
From: klemek <klemek.dev@proton.me>
Date: Sun, 9 Nov 2025 14:59:08 +0100
Subject: [PATCH] feat: isometrc grid

---
 DEVELOPMENT.md             |  5 +++--
 default/inc_functions.glsl | 45 ++++++++++++++++++++++++++++++++++++++
 default/inc_src.glsl       | 41 +++++++++++++++++++++++++++++++---
 3 files changed, 86 insertions(+), 5 deletions(-)

diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index 934af19..d3bf528 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -87,9 +87,10 @@ make -f Makefile.dev release-arch
 - [ ] Default project
   - [x] split with includes
   - [x] src  9 : sentences repeat h
-  - [ ] src 11 : isometric grid
+  - [x] src 10 : isometric grid
   - [ ] src 12 : pattern in my kitchen
-  - [ ] src 13 : ?
+  - [ ] src 13 : cursor with select
+  - [ ] src 14 : ?
   - [ ] src 15 : ?
   - [x] fx 11 : spill
   - [ ] fx 12 : colorize range (pretty color ranges)
diff --git a/default/inc_functions.glsl b/default/inc_functions.glsl
index 30f0d46..30db4c4 100644
--- a/default/inc_functions.glsl
+++ b/default/inc_functions.glsl
@@ -201,6 +201,51 @@ float h_rect(vec2 uv, vec2 c, vec2 size, float k) {
     return rect(uv, c, size + k * 0.5) - rect(uv, c, size - k * 0.5);
 }
 
+float line(vec2 uv, vec2 p1, vec2 p2, float thick) {
+    vec2 p = p2 - p1;
+    uv -= p1;
+    vec2 k;
+    
+    if (abs(p.y) > abs(p.x)) {
+        k = vec2(
+            uv.x - p.x * uv.y / p.y,
+            uv.y / p.y
+        );
+        
+        return step(k.x, thick * 0.5)
+            * step(-k.x, thick * 0.5)
+            * step(k.y, 1)
+            * (1 - step(k.y, 0));
+    } else {
+        k = vec2(
+            uv.x / p.x,
+            uv.y - p.y * uv.x / p.x
+        );
+        
+        return step(k.y, thick * 0.5)
+            * step(-k.y, thick * 0.5)
+            * step(k.x, 1)
+            * (1 - step(k.x, 0));
+    }
+}
+
+const mat2x2 ISOMETRIC_MATRIX = {{0.5, 1}, {0.5, -1}};
+
+vec2 iso(vec2 p) {
+    return p * ISOMETRIC_MATRIX;
+}
+
+vec2 iso_z(float z) {
+    return vec2(
+        -z,
+        z
+    );
+}
+
+vec2 iso(vec3 uv) {
+    return iso(uv.xy) + iso_z(uv.z);
+}
+
 // INPUTS
 
 vec4 reframe(sampler2D tex, vec2 uv)
diff --git a/default/inc_src.glsl b/default/inc_src.glsl
index 220a46c..84e0bff 100644
--- a/default/inc_src.glsl
+++ b/default/inc_src.glsl
@@ -280,10 +280,9 @@ subroutine(src_stage_sub) vec4 src_9(vec2 vUV, int seed, vec3 b1, vec2 f1, vec3
     return vec4(f);
 }
 
-// TODO SRC 10
+// SRC 10 : isometric grid
 subroutine(src_stage_sub) vec4 src_10(vec2 vUV, int seed, vec3 b1, vec2 f1, vec3 b2, vec2 f2, vec3 b3, vec2 f3)
 {
-    return src_3(vUV, seed, b1, f1, b2, f2, b3, f3);
     // start
 
 	vec2 uv0 = vUV.st;
@@ -292,9 +291,45 @@ subroutine(src_stage_sub) vec4 src_10(vec2 vUV, int seed, vec3 b1, vec2 f1, vec3
 
     // controls
 
+    float zoom = 5 + magic(f1, b1, seed + 10) * 15;
+    float h_scroll = magic(f2, b2, seed + 20);
+    float max_elevation = magic(f3, b3, seed + 30) * 0.5;
+    float thick = 0.1;
+
     // logic
+
+    vec2 uv2 = uv1;
+
+    vec2 uv3 = iso(uv2);
+
+    uv3 += vec2(h_scroll, 0);
+
+    uv3 *= round(zoom);
+
+    vec2 umax = vec2(round(zoom), 300);
+
+    vec2 u0 = mod(floor(uv3), umax);
+    vec2 u1 = mod(floor(uv3 + vec2(1, 0)), umax);
+    vec2 u2 = mod(floor(uv3 + vec2(0, 1)), umax);
+    vec2 u3 = mod(floor(uv3 + vec2(-1, 0)), umax);
+    vec2 u4 = mod(floor(uv3 + vec2(0, -1)), umax);
     
-    return texture(iTex0, vUV);
+    float e0 = (rand(floor(u0)) * 2 - 1) * max_elevation;
+    float e1 = (rand(floor(u1)) * 2 - 1) * max_elevation;
+    float e2 = (rand(floor(u2)) * 2 - 1) * max_elevation;
+    float e3 = (rand(floor(u3)) * 2 - 1) * max_elevation;
+    float e4 = (rand(floor(u4)) * 2 - 1) * max_elevation;
+
+    uv3 = mod(uv3, 1.0) - 0.5;
+
+    float f = 0;
+
+    f = line(uv3, vec2(0, 0) - iso_z(e0), vec2(1, 0) - iso_z(e1), thick)
+        + line(uv3, vec2(0, 0) - iso_z(e0), vec2(0, 1) - iso_z(e2), thick)
+        + line(uv3, vec2(0, 0) - iso_z(e0), vec2(-1, 0) - iso_z(e3), thick)
+        + line(uv3, vec2(0, 0) - iso_z(e0), vec2(0, -1) - iso_z(e4), thick);
+    
+    return vec4(f);
 }
 
 // SRC 11 : video in 2 + thru