-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathcommon.lua
More file actions
579 lines (483 loc) · 17.6 KB
/
Copy pathcommon.lua
File metadata and controls
579 lines (483 loc) · 17.6 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
--require("lldebugger").start()
require('algebra')
s = 50 -- size
polygon_x = { -- x=0
{ z = 0, y = 0, x = 0 },
{ z = 0, y = s, x = 0 },
{ z = s, y = s, x = 0 },
{ z = s, y = 0, x = 0 },
color = { 0, 1, 1 },
}
polygon_x2 = { -- x=s
{ z = s, y = 0, x = s },
{ z = s, y = s, x = s },
{ z = 0, y = s, x = s },
{ z = 0, y = 0, x = s },
color = { 0, 0, 1 }
}
polygon_y = { -- y=0
{ x = 0, z = 0, y = 0 },
{ x = 0, z = s, y = 0 },
{ x = s, z = s, y = 0 },
{ x = s, z = 0, y = 0 },
color = { 1, 1, 1 },
}
polygon_y2 = { -- y=s
{ x = s, z = 0, y = s },
{ x = s, z = s, y = s },
{ x = 0, z = s, y = s },
{ x = 0, z = 0, y = s },
color = { 0, 0, 1 }
}
polygon_z = { -- z=0
{ x = s, y = 0, z = 0 },
{ x = s, y = s, z = 0 },
{ x = 0, y = s, z = 0 },
{ x = 0, y = 0, z = 0 },
color = { 1, 0, 0 }
}
polygon_z2 = { -- z=s
{ x = 0, y = 0, z = s },
{ x = 0, y = s, z = s },
{ x = s, y = s, z = s },
{ x = s, y = 0, z = s },
color = { 1, 1, 0 },
}
polygons_original = {
polygon_x, polygon_x2,
polygon_y, polygon_y2,
polygon_z, polygon_z2,
}
function convert_polygons_to_triangles(polygons_original)
local triangles_original = {}
for _, polygon_iterated in ipairs(polygons_original) do
if #polygon_iterated == 4 then
local triangle1, triangle2
triangle1 = {
color = polygon_iterated.color,
polygon_iterated[1],
polygon_iterated[2],
polygon_iterated[3],
}
triangle2 = {
color = polygon_iterated.color,
polygon_iterated[3],
polygon_iterated[4],
polygon_iterated[1],
}
table.insert(triangles_original, triangle1)
table.insert(triangles_original, triangle2)
end
end
return triangles_original
end
triangles_original = convert_polygons_to_triangles(polygons_original)
--*****************************************
require("loader")
local file_path = "assets/stl-ascii-teapot-axes.stl"
local vertices_bounds
---triangles_original= load_stl_file(file_path)
triangles_original = {}
----print("bounding box", string.format("x %f %f, y %f %f, z %f %f", unpack(vertices_bounds) ) )
---triangles_original= load_obj_file"assets/teapot.obj"
function mesh_center(triangles)
local x_min, x_max = math.huge, -math.huge
local y_min, y_max = math.huge, -math.huge
local z_min, z_max = math.huge, -math.huge
for _, tri in ipairs(triangles) do
for _, v in ipairs(tri) do
if v.x < x_min then x_min = v.x end
if v.x > x_max then x_max = v.x end
if v.y < y_min then y_min = v.y end
if v.y > y_max then y_max = v.y end
if v.z < z_min then z_min = v.z end
if v.z > z_max then z_max = v.z end
end
end
return { x = (x_min + x_max) / 2, y = (y_min + y_max) / 2, z = (z_min + z_max) / 2 }
end
--*****************************************
function point_translate(point, x, y, z)
return {
x = point.x + x,
y = point.y + y,
z = point.z + z
}
end
--[[
function point_rotate(point, radiants)
return {
x = math.cos(radiants)*point.x - math.sin(radiants)*point.y ,
y = math.cos(radiants)*point.y + math.sin(radiants)*point.x }
end --]]
function point_rotate_axes(axes, point_in, radiants)
local point_out = { x = point_in.x, y = point_in.y, z = point_in.z }
local one, two = string.sub(axes, 1, 1), string.sub(axes, 2, 2)
point_out[one] = math.cos(radiants) * point_in[one] - math.sin(radiants) * point_in[two]
point_out[two] = math.cos(radiants) * point_in[two] + math.sin(radiants) * point_in[one]
return point_out
end
function point_rotate_z(point, radiants)
return point_rotate_axes('xy', point, radiants)
end
function point_rotate_y(point, radiants)
return point_rotate_axes('xz', point, radiants)
end
function polygon_transform(polygon, degrees, center)
center = center or { x = 0, y = 0, z = 0 }
local radiants = (degrees / 360) * (math.pi * 2)
local polygon_origin = {}
for i, point in ipairs(polygon) do
table.insert(polygon_origin, point_translate(point,
-center.x, -center.y, -center.z
))
end
--[[
local polygon_rotated1={}
for i,point in ipairs(polygon_origin) do
table.insert( polygon_rotated1, point_rotate_z(point, 0 ) ) -- radiants | 0
end
--]]
local polygon_rotated2 = {}
for i, point in ipairs(polygon_origin) do --- polygon_rotated1
table.insert(polygon_rotated2, point_rotate_y(point, radiants)) -- radiants | 0
end
local polygon_rotated_translated = {}
for i, point in ipairs(polygon_rotated2) do
table.insert(polygon_rotated_translated, point_translate(point, 150, 150, -400))
end
local polygon_transformed = polygon_rotated_translated
polygon_transformed.color = polygon.color -- same color
---[[
if polygon[1].normal then
polygon_transformed[1].normal = point_rotate_y(polygon[1].normal, radiants) -- same normal WIP
polygon_transformed[2].normal = point_rotate_y(polygon[2].normal, radiants) -- same normal WIP
polygon_transformed[3].normal = point_rotate_y(polygon[3].normal, radiants) -- same normal WIP
end
if polygon[1].uv then
polygon_transformed[1].uv = polygon[1].uv
polygon_transformed[2].uv = polygon[2].uv
polygon_transformed[3].uv = polygon[3].uv
end
--]]
return polygon_transformed
end
degrees = 0.0
local obj_cube = load_obj_file("assets/head.obj")
obj_cube.center = mesh_center(obj_cube)
--obj_cube = {} -- WIP to simplify
local obj_uv_plane = load_obj_file("assets/uv_plane.obj")
obj_uv_plane.center = mesh_center(obj_uv_plane)
local obj_floor = load_obj_file("assets/floor_plane.obj")
obj_floor.center = { x = 0, y = 0, z = 0 } -- preserve y=-100 world position
function update(dt)
local degrees_increment
degrees_increment = dt * 45
degrees = (degrees + degrees_increment) % 360
local polygons_transformed = {}
function polygons_transform(polygons, degrees)
assert(polygons)
local center = polygons.center or { x = 0, y = 0, z = 0 }
for i, polygon in ipairs(polygons) do
table.insert(polygons_transformed, polygon_transform(polygon, degrees, center))
end
return polygons_transformed
end
polygons_transformed = polygons_transform(triangles_original, degrees)
---polygons_transformed = triangles_original
polygons_transformed = polygons_transform(obj_cube, (degrees + 180) % 360)
polygons_transformed = polygons_transform(obj_floor, 0)
---polygons_transformed = polygons_transform(obj_uv_plane, 0)
local s = 50
local depth = 10
local polygon_z2 = { -- z=s
{ x = 0, y = 0, z = depth },
{ x = 0, y = s, z = depth },
{ x = s, y = s, z = depth },
{ x = s, y = 0, z = depth },
color = { 1, 1, 0 },
}
local polygons_transformed_addon
polygons_transformed_addon = {
polygon_z2, -- WIP TODO turno off this debug helper, comment-out this line
}
polygons_transformed_addon = convert_polygons_to_triangles(
polygons_transformed_addon)
-- polygons_transformed_addon = convert_polygons_to_triangles( { polygon_z2 } )
local polygons_accumulator = polygons_transformed
for i, polygon in ipairs(polygons_transformed_addon) do
table.insert(polygons_accumulator, polygon)
end
polygons_to_render = polygons_accumulator
end
function shading(polygon_iterated)
--[[
if not polygon_iterated.normal then -- caching
polygon_iterated.normal = polygon_normal(polygon_iterated)
end
--]]
local normal_vector = polygon_normal(polygon_iterated) -- not cached
--[[
function polygon_iterated.depth(px, py)
if not polygon_iterated.normal then -- caching, it's cached
polygon_iterated.normal = polygon_normal(polygon_iterated)
end
local x,y,z,x1,y1,z1,a,b,c
local normal_vector = polygon_iterated.normal -- cached
x=px
y=py
x1=polygon_iterated[1].x
y1=polygon_iterated[1].y
z1=polygon_iterated[1].z
a=normal_vector.x
b=normal_vector.y
c=normal_vector.z
z = -(a*x +b*y -(a*x1 +b*y1 +c*z1) )/c
return z
end
--]]
--[[
shaded_color=color*(dot(facing_direction,light_direction))
i.e. face_color scaled to cos_angle obtained as
vector dot product of face_normal and to_light vectors
--]]
if not polygon_iterated.color_diffuse then
local color = polygon_iterated.color or { 1, 1, 0 } -- default if missing
local face_normal = normal_vector -- not cached
local to_light = vunit({ x = -1, y = -1, z = -1 })
local cos_angle = vdot(face_normal, to_light)
cos_angle = unit_clamp(cos_angle)
color = scale3(cos_angle, color)
local ambient_light_intensity = 0.4
local ambient_light_color = {
ambient_light_intensity,
ambient_light_intensity,
ambient_light_intensity }
color = sum3(color, ambient_light_color)
color = clamp3(color)
polygon_iterated.color_diffuse = color
end
end
function perspective(polygon_iterated)
local cx, cy = 150, 150 -- screen center (matches window 300x300)
local focal = 200 -- focal length; objects at z=-200 appear at natural size
for i, vertex in ipairs(polygon_iterated) do
vertex.inv_z = 1.0 / (-vertex.z) -- store for perspective-correct UV
vertex.x = (vertex.x - cx) * (focal * vertex.inv_z) + cx
vertex.y = (vertex.y - cy) * (focal * vertex.inv_z) + cy
-- vertex.z left unchanged (used for depth testing)
end
end
function vertex_color_from_vertex_normal(triangle, vertex, color, to_light, ambient_light_color)
local normal
if vertex.normal then
normal = vertex.normal
else
normal = polygon_normal(triangle)
end
local cos_angle = vdot(normal, to_light)
cos_angle = unit_clamp(cos_angle)
color = scale3(cos_angle, color)
color = sum3(color, ambient_light_color)
color = clamp3(color)
vertex.color = color
end
function shading_smooth_preset1(triangle)
local ambient_light_intensity = 0.4
local ambient_light_color = {
ambient_light_intensity,
ambient_light_intensity,
ambient_light_intensity }
local surface_color = { 1, 0.5, 0.5 }
local lights = {
vunit({ x = -1, y = -1, z = -1 }), -- top-left-back
vunit({ x = 1, y = 0, z = -1 }), -- right-front
vunit({ x = 0, y = 1, z = 0 }), -- top-down (illuminates floor)
}
for _, vertex in ipairs({ triangle[1], triangle[2], triangle[3] }) do
local normal = vertex.normal or polygon_normal(triangle)
local diffuse = { 0, 0, 0 }
for _, to_light in ipairs(lights) do
local cos = unit_clamp(vdot(normal, to_light))
diffuse = sum3(diffuse, scale3(cos, surface_color))
end
vertex.color = clamp3(sum3(diffuse, ambient_light_color))
end
end
local function halfplane(px, p1, p2)
return ((p2.x - p1.x) * (px.y - p1.y) - (p2.y - p1.y) * (px.x - p1.x)) < 0
end
local function inside_polygon(polygon, point)
local last = polygon[#polygon]
for i = 1, #polygon do
local current = polygon[i]
if halfplane(point, last, current) then return false end
last = current
end
return true
end
local pixel_point = { x = 0, y = 0 } -- reused each pixel, avoids allocation
local pixel_xy = { 0, 0 } -- reused for draw_pixel call
local pixel_rgb = { 0, 0, 0 } -- reused for Gouraud color output, avoids allocation
local render_width, render_height = 300, 300
local depth_buffer = {}
do
for py = 0, render_height do
depth_buffer[py] = {}
for px = 0, render_width do depth_buffer[py][px] = -math.huge end
end
end
local front_facing = {} -- reused each frame
function draw()
-- backface cull in 3D before shading/perspective
-- nz = z-component of face normal; >= 0 means front-facing (camera along -Z)
local n = 0
for i, polygon_iterated in ipairs(polygons_to_render) do
local v0, v1, v2 = polygon_iterated[1], polygon_iterated[2], polygon_iterated[3]
local nz = (v1.x - v0.x) * (v2.y - v0.y) - (v1.y - v0.y) * (v2.x - v0.x)
if nz >= 0 then
n = n + 1
front_facing[n] = polygon_iterated
end
end
for i = n + 1, #front_facing do front_facing[i] = nil end
for i = 1, n do
shading_smooth_preset1(front_facing[i])
end
for i = 1, n do
perspective(front_facing[i])
end
-- z-buffer reset
for py = 0, render_height do
local line = depth_buffer[py]
for px = 0, render_width do line[px] = -math.huge end
end
--[[
-- pixels
for py=0,render_height do
for px=0,render_width do
for i,polygon_iterated in ipairs(polygons_to_render) do
local check = false
check = in_convex_polygon(px, py, polygon_iterated)
--]]
-- testing: function color_interpolate(point, polygon)
--polygons_to_render = {}
--[[
table.insert(polygons_to_render,
{
{x=300, y=10, z=10, color={1,1,0}},
{x=10, y=10, z=10, color={1,0,0}},
{x=10, y=300,z=10, color={0,1,0}},
}
)
--]]
for i = 1, n do
local polygon_iterated = front_facing[i]
local x_min = math.huge
local x_max = -math.huge
local y_min = math.huge
local y_max = -math.huge
for i, point in ipairs(polygon_iterated) do
if point.x < x_min then x_min = point.x end
if point.x > x_max then x_max = point.x end
if point.y < y_min then y_min = point.y end
if point.y > y_max then y_max = point.y end
end
x_min = math.max(math.floor(x_min), 0)
x_max = math.min(math.floor(x_max), render_width)
y_min = math.max(math.floor(y_min), 0)
y_max = math.min(math.floor(y_max), render_height)
local pre = barycentric_coords_precalculated_for_polygon(polygon_iterated)
-- Skip degenerate triangles (zero area, would cause division by zero).
if pre.common == 0 then goto next_polygon end
-- Cache vertex data in locals — faster than repeated table indexing in the hot loop.
local v0, v1, v2 = polygon_iterated[1], polygon_iterated[2], polygon_iterated[3]
local v0z, v1z, v2z = v0.z, v1.z, v2.z
local color_diffuse = polygon_iterated.color_diffuse -- flat shading (nil for Gouraud)
local has_uv = v0.uv ~= nil
-- Gouraud per-vertex colors (only used when color_diffuse is nil).
local c0, c1, c2
if not color_diffuse then
c0, c1, c2 = v0.color, v1.color, v2.color
end
-- Per-vertex UV and inv_z for perspective-correct texture mapping.
local u0, u1, u2, t0, t1, t2, iz0, iz1, iz2
if has_uv then
u0, u1, u2 = v0.uv[1], v1.uv[1], v2.uv[1]
t0, t1, t2 = v0.uv[2], v1.uv[2], v2.uv[2]
iz0, iz1, iz2 = v0.inv_z, v1.inv_z, v2.inv_z
end
-- Incremental (scanline) rasterisation.
--
-- Key idea: barycentric coordinates are LINEAR functions of (px, py).
-- ra(px,py) = (ax*(px-cx) + ay*(py-cy)) / common
-- rb(px,py) = (bx*(px-cx) + by*(py-cy)) / common
-- rc = 1 - ra - rb
--
-- Along a scanline (fixed py, px increasing by 1), ra_num increases by ax each step
-- and rb_num increases by bx. So we seed at x_min then just ADD per step — no
-- multiplications inside the pixel loop.
--
-- We also DEFER the division by common until we know the pixel is inside the triangle,
-- because most pixels in the bounding box are outside. The sign of the numerators
-- (assuming common > 0 from CCW winding) is enough for the inside test.
local inv_common = 1.0 / pre.common
local ax, bx, drc = pre.ax, pre.bx, pre.drc
for py = y_min, y_max do
local dy = py - pre.cy
-- Seed the numerators at the left edge of this scanline.
local ra_num = ax * (x_min - pre.cx) + pre.ay * dy
local rb_num = bx * (x_min - pre.cx) + pre.by * dy
local rc_num = pre.common - ra_num - rb_num
local depth_line = depth_buffer[py]
local screen_py = (render_height - 1) - py -- y-axis flip for display
for px = x_min, x_max do
-- Inside test: all three barycentric numerators must be non-negative
-- (equivalent to the point being on the correct side of all three edges).
if ra_num >= 0 and rb_num >= 0 and rc_num >= 0 then
-- Now divide once to get the normalised weights.
local ra = ra_num * inv_common
local rb = rb_num * inv_common
local rc = rc_num * inv_common -- == 1 - ra - rb
-- Depth interpolation (replaces position_interpolate_precalc).
local z = ra*v0z + rb*v1z + rc*v2z
if z > depth_line[px] then
local rgb
if color_diffuse then
rgb = color_diffuse -- flat shading: single color for whole face
else
-- Gouraud shading: interpolate per-vertex colors (replaces color_interpolate_precalc).
-- Each channel is a weighted blend: color = ra*c0 + rb*c1 + rc*c2.
pixel_rgb[1] = ra*c0[1] + rb*c1[1] + rc*c2[1]
pixel_rgb[2] = ra*c0[2] + rb*c1[2] + rc*c2[2]
pixel_rgb[3] = ra*c0[3] + rb*c1[3] + rc*c2[3]
rgb = pixel_rgb
end
-- Texture mapping: blend the texel with the Gouraud color.
if has_uv then
-- Perspective-correct UV: interpolate u/z and 1/z, then divide.
-- This prevents the "swimming" distortion of simple affine UV mapping.
local inv_z = ra*iz0 + rb*iz1 + rc*iz2
local u = (ra*u0*iz0 + rb*u1*iz1 + rc*u2*iz2) / inv_z
local t = (ra*t0*iz0 + rb*t1*iz1 + rc*t2*iz2) / inv_z
local tex = sample_texture(u, t)
pixel_rgb[1] = rgb[1] * tex[1]
pixel_rgb[2] = rgb[2] * tex[2]
pixel_rgb[3] = rgb[3] * tex[3]
rgb = pixel_rgb
end
pixel_xy[1] = px
pixel_xy[2] = screen_py
draw_pixel(rgb, pixel_xy)
depth_line[px] = z
end
end
-- Advance barycentric numerators by one pixel (3 additions, no multiplications).
ra_num = ra_num + ax
rb_num = rb_num + bx
rc_num = rc_num + drc
end
end
::next_polygon::
end -- front_facing loop
end