tb/models: add gfx model

1 files changed, 128 insertions, 0 deletions

diff --git a/tb/models/gfx.py b/tb/models/gfx.py
new file mode 100644
index 0000000..c43a315
--- /dev/null
+++ b/tb/models/gfx.py
@@ -0,0 +1,128 @@
+import math, sys
+from PIL import Image
+
+W, H = 640, 480
+FILL = (0, 0, 0)
+
+fb = None
+
+def fixed_color(color):
+    for c in color[:3]:
+        c = abs(int(c * (1 << 8)))
+        yield (c & 255) | (255 if (c & (1 << 8)) else 0)
+
+def fixed(p):
+    pos, color = p
+    w = pos
+    pos = tuple(int(c / pos[3] * (1 << 13)) for c in pos[:3])
+    return (pos, tuple(fixed_color(color)))
+
+def bounding(p0, p1, p2):
+    minx = max(min(p0[0][0], p1[0][0], p2[0][0]), (-W // 2) << 4)
+    maxx = min(max(p0[0][0], p1[0][0], p2[0][0]), (W // 2) << 4)
+    miny = max(min(p0[0][1], p1[0][1], p2[0][1]), (-H // 2) << 4)
+    maxy = min(max(p0[0][1], p1[0][1], p2[0][1]), (H // 2) << 4)
+    return (minx, miny, maxx, maxy)
+
+def edge_fn(p, q, sx, sy):
+    p, q = p[0], q[0]
+
+    # https://www.scratchapixel.com/lessons/3d-basic-rendering/rasterization-practical-implementation/rasterization-stage.html
+    a, b = p[1] - q[1], -(p[0] - q[0])
+    r = (sx - q[0]) * a + (sy - q[1]) * b
+    return r, r, a, b
+
+def raster(p0, p1, p2, msaa=False):
+    global fb
+
+    minx, miny, maxx, maxy = bounding(p0, p1, p2)
+
+    sx, sy = minx // 16 * 16, miny // 16 * 16
+
+    base_x_a, base_y_a, add_x_a, add_y_a = edge_fn(p0, p1, sx, sy)
+    base_x_b, base_y_b, add_x_b, add_y_b = edge_fn(p1, p2, sx, sy)
+    base_x_c, base_y_c, add_x_c, add_y_c = edge_fn(p2, p0, sx, sy)
+
+    int_x_a = add_x_a << 4
+    int_x_b = add_x_b << 4
+    int_x_c = add_x_c << 4
+    int_y_a = add_y_a << 4
+    int_y_b = add_y_b << 4
+    int_y_c = add_y_c << 4
+
+    if msaa:
+        samples = ((-5, 10), (11, 2), (-7, -4))
+    else:
+        samples = ((0, 0),)
+
+    samples_a = tuple(add_x_a * sx + add_y_a * sy for sx, sy in samples)
+    samples_b = tuple(add_x_b * sx + add_y_b * sy for sx, sy in samples)
+    samples_c = tuple(add_x_c * sx + add_y_c * sy for sx, sy in samples)
+
+    for x in range(minx // 16 * 16, maxx + 16, 16):
+        for y in range(miny // 16 * 16, maxy + 16, 16):
+            count = 0
+
+            for a, b, c in zip(samples_a, samples_b, samples_c):
+                b0 = base_y_a + a
+                b1 = base_y_b + b
+                b2 = base_y_c + c
+                if b0 >= 0 and b1 >= 0 and b2 >= 0:
+                    count += 1
+
+            if count > 0:
+                s = b0 + b1 + b2
+                b0 /= s
+                b1 /= s
+                b2 /= s
+                yield (x >> 4, y >> 4, b0, b1, b2)
+
+            base_y_a += int_y_a
+            base_y_b += int_y_b
+            base_y_c += int_y_c
+
+        base_x_a += int_x_a
+        base_x_b += int_x_b
+        base_x_c += int_x_c
+
+        base_y_a = base_x_a
+        base_y_b = base_x_b
+        base_y_c = base_x_c
+
+def backend():
+    tri = (((-5 / 320, -5 / 240, 1.0, 1.0), (0.0, 0.0, 0.0, 1.0)),
+           ((-50/320, -5/240, 1.0, 1.0), (0.0, 1.0, 0.0, 0.0)),
+           ((-20/320,  -70/240, 1.0, 1.0), (0.0, 0.0, 1.0, 0.0)))
+
+    t = tri
+
+    tri = tuple(fixed(p) for p in tri)
+    for x, y, b0, b1, b2 in raster(*tri):
+        if -W // 2 <= x < W // 2 and -H // 2 <= y < H // 2:
+            r = b0 * t[0][1][1] + b1 * t[1][1][1] + b2 * t[2][1][1]
+            g = b0 * t[0][1][2] + b1 * t[1][1][2] + b2 * t[2][1][2]
+            b = b0 * t[0][1][3] + b1 * t[1][1][3] + b2 * t[2][1][3]
+
+            x += W // 2
+            y = H // 2 - y - 1
+            fb[y * W + x] = (int(r * 255), int(g * 255), int(b * 255))
+
+imgs = []
+
+def do_frame():
+    global fb, imgs
+    fb = [FILL] * W * H
+    backend()
+
+    image = Image.new('RGB', (W, H))
+    image.putdata(fb)
+    imgs.append(image)
+
+for n in range(1):
+    do_frame()
+
+imgs[0].save('out.gif',
+             save_all=True,
+             append_images=imgs[1:],
+             duration=100,
+             loop=0)