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
|
/**
* @file llpatchvertexarray.cpp
* @brief Implementation of the LLSurfaceVertexArray class.
*
* Copyright (c) 2001-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#include "llviewerprecompiledheaders.h"
#include "llpatchvertexarray.h"
#include "llsurfacepatch.h"
// constructors
LLPatchVertexArray::LLPatchVertexArray() :
mSurfaceWidth(0),
mPatchWidth(0),
mPatchOrder(0),
mRenderLevelp(NULL),
mRenderStridep(NULL)
{
}
LLPatchVertexArray::LLPatchVertexArray(U32 surface_width, U32 patch_width, F32 meters_per_grid) :
mRenderLevelp(NULL),
mRenderStridep(NULL)
{
create(surface_width, patch_width, meters_per_grid);
}
LLPatchVertexArray::~LLPatchVertexArray()
{
destroy();
}
void LLPatchVertexArray::create(U32 surface_width, U32 patch_width, F32 meters_per_grid)
{
// PART 1 -- Make sure the arguments are good...
// Make sure patch_width is not greater than surface_width
if (patch_width > surface_width)
{
U32 temp = patch_width;
patch_width = surface_width;
surface_width = temp;
}
// Make sure (surface_width-1) is equal to a power_of_two.
// (The -1 is there because an LLSurface has a buffer of 1 on
// its East and North edges).
U32 power_of_two = 1;
U32 surface_order = 0;
while (power_of_two < (surface_width-1))
{
power_of_two *= 2;
surface_order += 1;
}
if (power_of_two == (surface_width-1))
{
mSurfaceWidth = surface_width;
// Make sure patch_width is a factor of (surface_width - 1)
U32 ratio = (surface_width - 1) / patch_width;
F32 fratio = ((float)(surface_width - 1)) / ((float)(patch_width));
if ( fratio == (float)(ratio))
{
// Make sure patch_width is a power of two
power_of_two = 1;
U32 patch_order = 0;
while (power_of_two < patch_width)
{
power_of_two *= 2;
patch_order += 1;
}
if (power_of_two == patch_width)
{
mPatchWidth = patch_width;
mPatchOrder = patch_order;
}
else // patch_width is not a power of two...
{
mPatchWidth = 0;
mPatchOrder = 0;
}
}
else // patch_width is not a factor of (surface_width - 1)...
{
mPatchWidth = 0;
mPatchOrder = 0;
}
}
else // surface_width is not a power of two...
{
mSurfaceWidth = 0;
mPatchWidth = 0;
mPatchOrder = 0;
}
// PART 2 -- Allocate memory for the render level table
if (mPatchWidth > 0)
{
mRenderLevelp = new U32 [2*mPatchWidth + 1];
mRenderStridep = new U32 [mPatchOrder + 1];
}
if (NULL == mRenderLevelp || NULL == mRenderStridep)
{
// init() and some other things all want to deref these
// pointers, so this is serious.
llerrs << "mRenderLevelp or mRenderStridep was NULL; we'd crash soon." << llendl;
return;
}
// Now that we've allocated memory, we can initialize
// the arrays...
init();
}
void LLPatchVertexArray::destroy()
{
if (mPatchWidth == 0)
{
return;
}
delete [] mRenderLevelp;
delete [] mRenderStridep;
mSurfaceWidth = 0;
mPatchWidth = 0;
mPatchOrder = 0;
}
void LLPatchVertexArray::init()
// Initializes the triangle strip arrays.
{
U32 j;
U32 level, stride;
U32 k;
// We need to build two look-up tables...
// render_level -> render_stride
// A 16x16 patch has 5 render levels : 2^0 to 2^4
// render_level render_stride
// 4 1
// 3 2
// 2 4
// 1 8
// 0 16
stride = mPatchWidth;
for (level=0; level<mPatchOrder + 1; level++)
{
mRenderStridep[level] = stride;
stride /= 2;
}
// render_level <- render_stride.
/*
// For a 16x16 patch we'll clamp the render_strides to 0 through 16
// and enter the nearest render_level in the table. Of course, only
// power-of-two render strides are actually used.
//
// render_stride render_level
// 0 4
// 1 4 *
// 2 3 *
// 3 3
// 4 2 *
// 5 2
// 6 2
// 7 1
// 8 1 *
// 9 1
// 10 1
// 11 1
// 12 1
// 13 0
// 14 0
// 15 0
// 16 Always 0
level = mPatchOrder;
for (stride=0; stride<mPatchWidth; stride++)
{
if ((F32) stride > 2.1f * mRenderStridep[level])
{
level--;
};
mRenderLevelp[stride] = level;
}
*/
// This method is more agressive about putting triangles onscreen
level = mPatchOrder;
k = 2;
mRenderLevelp[0] = mPatchOrder;
mRenderLevelp[1] = mPatchOrder;
stride = 2;
while(stride < 2*mPatchWidth)
{
for (j=0; j<k && stride<2*mPatchWidth; j++)
{
mRenderLevelp[stride++] = level;
}
k *= 2;
level--;
}
mRenderLevelp[2*mPatchWidth] = 0;
}
std::ostream& operator<<(std::ostream &s, const LLPatchVertexArray &va)
{
U32 i;
s << "{ \n";
s << " mSurfaceWidth = " << va.mSurfaceWidth << "\n";
s << " mPatchWidth = " << va.mPatchWidth << "\n";
s << " mPatchOrder = " << va.mPatchOrder << "\n";
s << " mRenderStridep = \n";
for (i=0; i<va.mPatchOrder+1; i++)
{
s << " " << i << " " << va.mRenderStridep[i] << "\n";
}
s << " mRenderLevelp = \n";
for (i=0; i < 2*va.mPatchWidth + 1; i++)
{
s << " " << i << " " << va.mRenderLevelp[i] << "\n";
}
s << "}";
return s;
}
// EOF
|
