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
|
/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
/*
* This file is based on, or a modified version of code from TinyGL (C) 1997-2022 Fabrice Bellard,
* which is licensed under the MIT license (see LICENSE).
* It also has modifications by the ResidualVM-team, which are covered under the GPLv2 (or later).
*/
#include "graphics/tinygl/zbuffer.h"
namespace TinyGL {
template <bool kDepthWrite>
FORCEINLINE void FrameBuffer::putPixel(uint pixelOffset, int color, int x, int y, uint z) {
if (_enableScissor)
putPixel<kDepthWrite, true>(pixelOffset, color, x, y, z);
else
putPixel<kDepthWrite, false>(pixelOffset, color, x, y, z);
}
template <bool kDepthWrite, bool kEnableScissor>
FORCEINLINE void FrameBuffer::putPixel(uint pixelOffset, int color, int x, int y, uint z) {
if (kEnableScissor && scissorPixel(x, y)) {
return;
}
uint *pz = _zbuf + pixelOffset;
if (compareDepth(z, *pz)) {
writePixel<true, true, kDepthWrite>(pixelOffset, color, z);
}
}
template <bool kEnableScissor>
FORCEINLINE void FrameBuffer::putPixel(uint pixelOffset, int color, int x, int y) {
if (kEnableScissor && scissorPixel(x, y)) {
return;
}
writePixel<true, true>(pixelOffset, color);
}
template <bool kInterpRGB, bool kInterpZ, bool kDepthWrite>
void FrameBuffer::drawLine(const ZBufferPoint *p1, const ZBufferPoint *p2) {
if (_enableScissor)
drawLine<kInterpRGB, kInterpZ, kDepthWrite, true>(p1, p2);
else
drawLine<kInterpRGB, kInterpZ, kDepthWrite, false>(p1, p2);
}
template <bool kInterpRGB, bool kInterpZ, bool kDepthWrite, bool kEnableScissor>
void FrameBuffer::drawLine(const ZBufferPoint *p1, const ZBufferPoint *p2) {
// Based on Bresenham's line algorithm, as implemented in
// https://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#C
// with a loop exit condition based on the (unidimensional) taxicab
// distance between p1 and p2 (which is cheap to compute and
// rounding-error-free) so that interpolations are possible without
// code duplication.
// Where we are in unidimensional framebuffer coordinate
unsigned int pixelOffset = p1->y * _pbufWidth + p1->x;
// and in 2d
int x = p1->x;
int y = p1->y;
// How to move on each axis, in both coordinates systems
const int dx = abs(p2->x - p1->x);
const int inc_x = p1->x < p2->x ? 1 : -1;
const int dy = abs(p2->y - p1->y);
const int inc_y = p1->y < p2->y ? 1 : -1;
const int inc_y_pixel = p1->y < p2->y ? _pbufWidth : -_pbufWidth;
// When to move on each axis
int err = (dx > dy ? dx : -dy) / 2;
int e2;
// How many moves
int n = dx > dy ? dx : dy;
// kInterpZ
unsigned int z;
int sz;
// kInterpRGB
int r = p1->r >> (ZB_POINT_RED_BITS - 8);
int g = p1->g >> (ZB_POINT_GREEN_BITS - 8);
int b = p1->b >> (ZB_POINT_BLUE_BITS - 8);
int color = RGB_TO_PIXEL(r, g, b);
int sr, sg, sb;
if (kInterpZ) {
if (n == 0)
return;
sz = (p2->z - p1->z) / n;
z = p1->z;
}
if (kInterpRGB) {
sr = ((p2->r - p1->r) / n) >> (ZB_POINT_RED_BITS - 8);
sg = ((p2->g - p1->g) / n) >> (ZB_POINT_GREEN_BITS - 8);
sb = ((p2->b - p1->b) / n) >> (ZB_POINT_BLUE_BITS - 8);
}
while (n--) {
if (kInterpZ)
putPixel<kDepthWrite, kEnableScissor>(pixelOffset, color, x, y, z);
else
putPixel<kEnableScissor>(pixelOffset, color, x, y);
e2 = err;
if (e2 > -dx) {
err -= dy;
pixelOffset += inc_x;
x += inc_x;
}
if (e2 < dy) {
err += dx;
pixelOffset += inc_y_pixel;
y += inc_y;
}
if (kInterpZ)
z += sz;
if (kInterpRGB) {
r += sr;
g += sg;
b += sb;
color = RGB_TO_PIXEL(r, g, b);
}
}
}
void FrameBuffer::plot(ZBufferPoint *p) {
const uint pixelOffset = p->y * _pbufWidth + p->x;
const int col = RGB_TO_PIXEL(p->r, p->g, p->b);
const uint z = p->z;
if (_depthWrite && _depthTestEnabled)
putPixel<true>(pixelOffset, col, p->x, p->y, z);
else
putPixel<false>(pixelOffset, col, p->x, p->y, z);
}
void FrameBuffer::fillLineFlatZ(ZBufferPoint *p1, ZBufferPoint *p2) {
if (_depthWrite && _depthTestEnabled)
drawLine<false, true, true>(p1, p2);
else
drawLine<false, true, false>(p1, p2);
}
// line with color interpolation
void FrameBuffer::fillLineInterpZ(ZBufferPoint *p1, ZBufferPoint *p2) {
if (_depthWrite && _depthTestEnabled)
drawLine<true, true, true>(p1, p2);
else
drawLine<true, true, false>(p1, p2);
}
// no Z interpolation
void FrameBuffer::fillLineFlat(ZBufferPoint *p1, ZBufferPoint *p2) {
if (_depthWrite && _depthTestEnabled)
drawLine<false, false, true>(p1, p2);
else
drawLine<false, false, false>(p1, p2);
}
void FrameBuffer::fillLineInterp(ZBufferPoint *p1, ZBufferPoint *p2) {
if (_depthWrite && _depthTestEnabled)
drawLine<false, true, true>(p1, p2);
else
drawLine<false, true, false>(p1, p2);
}
void FrameBuffer::fillLineZ(ZBufferPoint *p1, ZBufferPoint *p2) {
// choose if the line should have its color interpolated or not
if (p1->r == p2->r && p1->g == p2->g && p1->b == p2->b)
fillLineFlatZ(p1, p2);
else
fillLineInterpZ(p1, p2);
}
void FrameBuffer::fillLine(ZBufferPoint *p1, ZBufferPoint *p2) {
// choose if the line should have its color interpolated or not
if (p1->r == p2->r && p1->g == p2->g && p1->b == p2->b)
fillLineFlat(p1, p2);
else
fillLineInterp(p1, p2);
}
} // end of namespace TinyGL
|
