examples: add an animated spirograph.v using gg

examples/gg/spirograph.v

@@ -0,0 +1,64 @@
+import gg
+import math
+
+const pixel_count = 15000
+const p = 3
+const s = math.pi * 2 / f32(pixel_count)
+const color = gg.Color{255, 255, 255, 255}
+const background = gg.Color{20, 20, 64, 255}
+const colors = [
+	gg.Color{255, 255, 255, 255},
+	gg.Color{255, 0, 255, 255},
+	gg.Color{255, 255, 0, 255},
+	gg.Color{0, 255, 255, 255},
+	gg.Color{0, 0, 255, 255},
+	gg.Color{0, 0, 0, 255},
+]!
+
+mut k := 497
+mut scale := 200
+gg.start(
+	window_title: 'Spirograph'
+	bg_color: background
+	width: 900
+	height: 950
+	sample_count: 2
+	frame_fn: fn [mut k, mut scale] (ctx &gg.Context) {
+		wsize := gg.window_size()
+		ctx.begin()
+		d := math.sin(f64(ctx.frame) / 300)
+		if math.abs(d) < 0.0015 {
+			k++
+		}
+		if ctx.pressed_keys[int(gg.KeyCode.left)] {
+			k--
+		}
+		if ctx.pressed_keys[int(gg.KeyCode.right)] {
+			k++
+		}
+		if ctx.pressed_keys[int(gg.KeyCode.up)] {
+			scale++
+		}
+		if ctx.pressed_keys[int(gg.KeyCode.down)] {
+			scale--
+		}
+		d600 := math.sin(f64(ctx.frame) / 60)
+		cd600 := math.cos(d600)
+		mut pdj, mut pkj := [p]f64{}, [p]f64{}
+		for j := 0; j < p; j++ {
+			pdj[j], pkj[j] = math.pow(d, j), math.pow(k, j)
+		}
+		for i := 0; i < pixel_count; i++ {
+			mut x, mut y := 0.0, 0.0
+			for j := 0; j < p; j++ {
+				a := pkj[j] * i * s
+				x += pdj[j] * math.sin(a) * cd600
+				y += pdj[j] * math.cos(a) * cd600
+			}
+			ctx.draw_rect_filled(f32(wsize.width / 2 + scale * x), f32(wsize.height / 2 + scale * y),
+				1, 1, colors[i % colors.len])
+		}
+		ctx.draw_text(wsize.width / 2 - 170, wsize.height - 15, 'frame: ${ctx.frame:06}, k: ${k:4}, scale: ${scale:4}, arrows to change')
+		ctx.end()
+	}
+)

thirdparty/sokol/util/sokol_gl.h

@@ -2309,7 +2309,7 @@ typedef struct {
 #define _SGL_DEFAULT_CONTEXT_POOL_SIZE (4)
 #define _SGL_DEFAULT_PIPELINE_POOL_SIZE (64)
 // __v_ start
-#define _SGL_DEFAULT_MAX_VERTICES (1<<17)
+#define _SGL_DEFAULT_MAX_VERTICES (1<<22)
 #define _SGL_DEFAULT_MAX_COMMANDS (1<<15)
 // __v_ end
 #define _SGL_SLOT_SHIFT (16)