From eff18cd1372141dd118ba6ebdd87578cab45bf68 Mon Sep 17 00:00:00 2001
From: Szabolcs Dombi <szabolcs@szabolcsdombi.com>
Date: Tue, 30 Jan 2024 21:50:33 +0200
Subject: [PATCH] headless examples and fractals

---
 examples/basic/fractal.py                     | 18 +++--
 examples/headless/headless_fractal.py         | 75 +++++++++++++++++++
 .../headless_hello_triangle.py}               | 13 ++--
 3 files changed, 96 insertions(+), 10 deletions(-)
 create mode 100644 examples/headless/headless_fractal.py
 rename examples/{advanced/hello_triangle_headless.py => headless/headless_hello_triangle.py} (79%)

diff --git a/examples/basic/fractal.py b/examples/basic/fractal.py
index fda37865..4edd2ece 100644
--- a/examples/basic/fractal.py
+++ b/examples/basic/fractal.py
@@ -35,9 +35,9 @@
 
         layout (location = 0) out vec4 out_color;
 
-        void main() {
-            vec2 z = vertex * 1.75;
-            vec2 c = vec2(0.4, 0.1);
+        float mandelbrot(vec2 uv) {
+            vec2 z = vec2(0.0, 0.0);
+            vec2 c = uv;
             int i;
             for (i = 0; i < 100; ++i) {
                 vec2 v = vec2(
@@ -47,8 +47,16 @@
                 if (dot(v, v) > 4.0) break;
                 z = v;
             }
-            float cm = fract((i == 100 ? 0.0 : float(i)) * 10.0 / 100.0);
-            out_color = vec4(fract(cm + 0.0 / 3.0), fract(cm + 1.0 / 3.0), fract(cm + 2.0 / 3.0), 1.0);
+            if (i == 100) {
+                i = 0;
+            }
+            return float(i) / 100.0;
+        }
+
+        void main() {
+            float cm = mandelbrot(vertex * 1.75 - vec2(0.5, 0.0));
+            vec3 color = vec3(0.2 + cm * 0.6, 0.4 + cm * 0.5, 1.0);
+            out_color = vec4(color * cm, 1.0);
         }
     ''',
     framebuffer=[image],
diff --git a/examples/headless/headless_fractal.py b/examples/headless/headless_fractal.py
new file mode 100644
index 00000000..6a92ffb9
--- /dev/null
+++ b/examples/headless/headless_fractal.py
@@ -0,0 +1,75 @@
+import os
+
+import zengl
+from PIL import Image
+
+zengl.init(zengl.loader(headless=True))
+
+ctx = zengl.context()
+
+image = ctx.image((8192, 8192), 'rgba8unorm', texture=False)
+
+pipeline = ctx.pipeline(
+    vertex_shader='''
+        #version 300 es
+        precision highp float;
+
+        vec2 vertices[3] = vec2[](
+            vec2(-1.0, -1.0),
+            vec2(3.0, -1.0),
+            vec2(-1.0, 3.0)
+        );
+
+        out vec2 vertex;
+
+        void main() {
+            gl_Position = vec4(vertices[gl_VertexID], 0.0, 1.0);
+            vertex = vertices[gl_VertexID];
+        }
+    ''',
+    fragment_shader='''
+        #version 300 es
+        precision highp float;
+
+        in vec2 vertex;
+
+        layout (location = 0) out vec4 out_color;
+
+        float mandelbrot(vec2 uv) {
+            vec2 z = vec2(0.0, 0.0);
+            vec2 c = uv;
+            int i;
+            for (i = 0; i < 100; ++i) {
+                vec2 v = vec2(
+                    (z.x * z.x - z.y * z.y) + c.x,
+                    (z.y * z.x + z.x * z.y) + c.y
+                );
+                if (dot(v, v) > 4.0) break;
+                z = v;
+            }
+            if (i == 100) {
+                i = 0;
+            }
+            return float(i) / 100.0;
+        }
+
+        void main() {
+            float cm = mandelbrot(vertex * 1.75 - vec2(0.5, 0.0));
+            vec3 color = vec3(0.2 + cm * 0.6, 0.4 + cm * 0.5, 1.0);
+            out_color = vec4(color * cm, 1.0);
+        }
+    ''',
+    framebuffer=[image],
+    topology='triangles',
+    vertex_count=3,
+)
+
+ctx.new_frame()
+image.clear()
+pipeline.render()
+ctx.end_frame()
+
+img = Image.frombuffer('RGBA', image.size, image.read(), 'raw', 'RGBA', 0, -1)
+img.save('fractal.png')
+
+print('Saved:', os.path.abspath('fractal.png'))
diff --git a/examples/advanced/hello_triangle_headless.py b/examples/headless/headless_hello_triangle.py
similarity index 79%
rename from examples/advanced/hello_triangle_headless.py
rename to examples/headless/headless_hello_triangle.py
index 25c18a91..e3b4c83c 100644
--- a/examples/advanced/hello_triangle_headless.py
+++ b/examples/headless/headless_hello_triangle.py
@@ -1,11 +1,13 @@
+import os
+
 import zengl
 from PIL import Image
 
-ctx = zengl.context(zengl.loader(headless=True))
+zengl.init(zengl.loader(headless=True))
+
+ctx = zengl.context()
 
-size = (1280, 720)
-image = ctx.image(size, 'rgba8unorm', samples=4)
-image.clear_value = (0.05, 0.05, 0.05, 1.0)
+image = ctx.image((1280, 720), 'rgba8unorm', samples=4)
 
 pipeline = ctx.pipeline(
     vertex_shader='''
@@ -53,5 +55,6 @@
 pipeline.render()
 ctx.end_frame()
 
-img = Image.frombuffer('RGBA', size, image.read(), 'raw', 'RGBA', 0, -1)
+img = Image.frombuffer('RGBA', image.size, image.read(), 'raw', 'RGBA', 0, -1)
 img.save('hello.png')
+print('Created:', os.path.abspath('hello.png'))