From ae82157d19f31bf16026ea71f356e24828dab05d Mon Sep 17 00:00:00 2001
From: cpsdqs <cpsdqs@gmail.com>
Date: Sat, 24 Oct 2020 23:27:16 +0200
Subject: [PATCH] Add interactive mandelbrot example

---
 .../mandelbrot/mandelbrot-interactive.csn     | 212 ++++++++++++++++++
 1 file changed, 212 insertions(+)
 create mode 100644 examples/mandelbrot/mandelbrot-interactive.csn

diff --git a/examples/mandelbrot/mandelbrot-interactive.csn b/examples/mandelbrot/mandelbrot-interactive.csn
new file mode 100644
index 0000000..4c2ab2a
--- /dev/null
+++ b/examples/mandelbrot/mandelbrot-interactive.csn
@@ -0,0 +1,212 @@
+(
+    (sc-init 1024 768)
+    (sc-opt SCREEN_AUTOBLIT 0)
+    (def W 1024)
+    (def H 768)
+    (def MAXITER 50)
+
+    ; size of big pixels
+    (def COL_SKIP 8)
+    (def ROW_SKIP 8)
+
+    (lds @cout "Interactive Mandelbrot\n")
+    (lds @cout "----------------------\n")
+    (lds @cout "Navigate using WASD, zoom using Q/E\n")
+    (lds @cout "To get a high-res image, stop interacting for while\n")
+
+    (sym asciigr r10)
+
+    (sym mb_x r2)
+    (sym mb_y r3)
+    (sym mb_s r4)
+    (sym mb_row r5)
+    (sym mb_col_skip r6)
+    (sym mb_row_skip r7)
+
+    (ld mb_x 0.0)
+    (ld mb_y 0.0)
+    (ld mb_s 1.0)
+    (sym did_change r14)
+    (sym is_first_render r15)
+    (ld is_first_render 1)
+
+    ; render row
+    ; big - is this the first render? if yes, use big pixels
+    ; col - mb_col_skip column offset
+    ; px - offset x
+    ; py - offset y
+    ; scale - scaling
+    ; row - row position
+    (proc render_row big col px py scale row
+        (sym gradient r9)
+        (mkbf gradient (
+            0x421e0f 0x19071a 0x09012f 0x040449 0x000764 0x0c2c8a 0x1852b1 0x397dd1 
+            0x86b5e5 0xd3ecf8 0xf1e9bf 0xf8c95f 0xffaa00 0xcc8000 0x995700 0x6a3403))
+
+        (sym x r7)
+        (sym y r8)
+        (add y row)
+        (ld x col)
+        (:col)
+            (call pixel x y px py scale)
+            (sub r0 MAXITER 1)
+            (rcmp res0 1 r0
+                (eq?
+                    (mod r0 res0 16)
+                    (bfrd r0 @gradient r0)
+                )
+                (else? (ld r0 0))
+            )
+            (cmp big 1)
+            (j.ne :not_big)
+            (sc-rect x y COL_SKIP ROW_SKIP r0)
+            (j :was_big)
+            (:not_big)
+            (sc-wr x y r0)
+            (:was_big)
+            (add x COL_SKIP)
+            (cmp x W)
+            (j.lt :col)
+        (sc-blit)
+        (ret))
+
+    (:slp)
+    (sc-poll)
+    ; did_change -- did the user interact during this frame?
+    (ld did_change 0)
+
+    ; scaled movement speed in r1
+    (fdiv r1 0.03 mb_s)
+
+    ; A <
+    (sc-key r0 KEY_A)
+    (j.z :a_not_pressed)
+    (fsub mb_x r1)
+    (ld did_change 1)
+    (:a_not_pressed)
+
+    ; W ^
+    (sc-key r0 KEY_W)
+    (j.z :w_not_pressed)
+    (fsub mb_y r1)
+    (ld did_change 1)
+    (:w_not_pressed)
+
+    ; S v
+    (sc-key r0 KEY_S)
+    (j.z :s_not_pressed)
+    (fadd mb_y r1)
+    (ld did_change 1)
+    (:s_not_pressed)
+
+    ; D >
+    (sc-key r0 KEY_D)
+    (j.z :d_not_pressed)
+    (fadd mb_x r1)
+    (ld did_change 1)
+    (:d_not_pressed)
+
+    ; Q +
+    (sc-key r0 KEY_Q)
+    (j.z :q_not_pressed)
+    (fmul mb_s 1.01)
+    (ld did_change 1)
+    (:q_not_pressed)
+
+    ; E -
+    (sc-key r0 KEY_E)
+    (j.z :e_not_pressed)
+    (fdiv mb_s 1.01)
+    (ld did_change 1)
+    (:e_not_pressed)
+
+    (cmp did_change 0)
+        (j.eq :did_not_move)
+        ; if something changed...
+
+        ; mark this as a first render and reset col_skip and row_skip
+        (ld is_first_render 1)
+        (ld mb_col_skip 0)
+        (ld mb_row_skip 0)
+    (:did_not_move)
+
+    ; render row mb_row + mb_row_skip
+    (ld r0 mb_row)
+    (add r0 mb_row_skip)
+    (call render_row is_first_render mb_col_skip mb_x mb_y mb_s r0)
+
+    (cmp mb_row H)
+        (j.ge :render_done)
+        ; if mb_row < H
+        (add mb_row ROW_SKIP)
+        (j :render_not_done)
+    (:render_done)
+        ; otherwise, this frame is done
+        (ld mb_row 0)
+        (add mb_col_skip 1)
+        (ld is_first_render 0)
+        (mod mb_col_skip COL_SKIP)
+
+        ; if mb_col_skip wrapped back to zero increase mb_row_skip
+        (cmp mb_col_skip 0)
+        (j.ne :not_col)
+        (add mb_row_skip 1)
+        (mod mb_row_skip ROW_SKIP)
+        (:not_col)
+    (:render_not_done)
+    (j :slp)
+
+    (proc pixel xi yi off_x off_y scale
+        (sym x0 r7) 
+        (sym y0 r8)
+        (itf x0 xi)
+        (itf y0 yi)
+
+        ; Scale to the interesting range x -2.5..1 and y -1..1
+        (itf r0 W)
+        (itf r1 H)
+
+        (fdiv x0 r0)
+        (fmul x0 3.5)
+        (fsub x0 2.5)
+
+        (fdiv y0 r1)
+        (fmul y0 2.4)
+        (fsub y0 1.2)
+
+        (fdiv x0 scale)
+        (fdiv y0 scale)
+        (fadd x0 off_x)
+        (fadd y0 off_y)
+
+        (sym x r5)
+        (sym y r6)
+        (ld x 0.0)
+        (ld y 0.0)
+        (sym iter r4)
+
+        (:iter)
+            (cmp iter MAXITER)
+            (j.eq :end)
+            (fmul r0 x x)
+            (fmul r1 y y)
+            (fadd r2 r1)
+            (fcmp r2 4.0)
+            (j.gt :end)
+
+            (fsub r2 r0 r1)
+            (fadd r2 x0)
+
+            (fmul r0 x y)
+            (fmul r0 2.0)
+            (fadd r0 y0)
+            (ld y r0)
+            (ld x r2)
+            (inc iter)
+            (j :iter)
+
+        (:end)
+        (ret iter)
+    )
+)
+