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1/**
2 * @file llrendersphere.cpp
3 * @brief implementation of the LLRenderSphere class.
4 *
5 * $LicenseInfo:firstyear=2001&license=internal$
6 *
7 * Copyright (c) 2001-2008, Linden Research, Inc.
8 *
9 * The following source code is PROPRIETARY AND CONFIDENTIAL. Use of
10 * this source code is governed by the Linden Lab Source Code Disclosure
11 * Agreement ("Agreement") previously entered between you and Linden
12 * Lab. By accessing, using, copying, modifying or distributing this
13 * software, you acknowledge that you have been informed of your
14 * obligations under the Agreement and agree to abide by those obligations.
15 *
16 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
17 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
18 * COMPLETENESS OR PERFORMANCE.
19 * $/LicenseInfo$
20 */
21
22// Sphere creates a set of display lists that can then be called to create
23// a lit sphere at different LOD levels. You only need one instance of sphere
24// per viewer - then call the appropriate list.
25
26#include "llviewerprecompiledheaders.h"
27#include "llrendersphere.h"
28#include "llerror.h"
29
30#include "llglheaders.h"
31
32GLUquadricObj *gQuadObj2 = NULL;
33LLRenderSphere gSphere;
34
35void drawSolidSphere(GLdouble radius, GLint slices, GLint stacks);
36
37void drawSolidSphere(GLdouble radius, GLint slices, GLint stacks)
38{
39 if (!gQuadObj2)
40 {
41 gQuadObj2 = gluNewQuadric();
42 if (!gQuadObj2)
43 {
44 llwarns << "drawSolidSphere couldn't allocate quadric" << llendl;
45 return;
46 }
47 }
48
49 gluQuadricDrawStyle(gQuadObj2, GLU_FILL);
50 gluQuadricNormals(gQuadObj2, GLU_SMOOTH);
51 // If we ever changed/used the texture or orientation state
52 // of quadObj, we'd need to change it to the defaults here
53 // with gluQuadricTexture and/or gluQuadricOrientation.
54 gluQuadricTexture(gQuadObj2, GL_TRUE);
55 gluSphere(gQuadObj2, radius, slices, stacks);
56}
57
58
59// lat = 0 is Z-axis
60// lon = 0, lat = 90 at X-axis
61void lat2xyz(LLVector3 * result, F32 lat, F32 lon)
62{
63 // Convert a latitude and longitude to x,y,z on a normal sphere and return it in result
64 F32 r;
65 result->mV[VX] = (F32) (cos(lon * DEG_TO_RAD) * sin(lat * DEG_TO_RAD));
66 result->mV[VY] = (F32) (sin(lon * DEG_TO_RAD) * sin(lat * DEG_TO_RAD));
67 r = (F32) pow(result->mV[VX] * result->mV[VX] + result->mV[VY] * result->mV[VY], 0.5f);
68 if (r == 1.0f)
69 {
70 result->mV[VZ] = 0.0f;
71 }
72 else
73 {
74 result->mV[VZ] = (F32) pow(1 - r*r, 0.5f);
75 if (lat > 90.01)
76 {
77 result->mV[VZ] *= -1.0;
78 }
79 }
80}
81
82void lat2xyz_rad(LLVector3 * result, F32 lat, F32 lon)
83{
84 // Convert a latitude and longitude to x,y,z on a normal sphere and return it in result
85 F32 r;
86 result->mV[VX] = (F32) (cos(lon) * sin(lat));
87 result->mV[VY] = (F32) (sin(lon) * sin(lat));
88 r = (F32) pow(result->mV[VX] * result->mV[VX] + result->mV[VY] * result->mV[VY], 0.5f);
89 if (r == 1.0f)
90 result->mV[VZ] = 0.0f;
91 else
92 {
93 result->mV[VZ] = (F32) pow(1 - r*r, 0.5f);
94 if (lat > F_PI_BY_TWO) result->mV[VZ] *= -1.0;
95 }
96}
97
98// A couple thoughts on sphere drawing:
99// 1) You need more slices than stacks, but little less than 2:1
100// 2) At low LOD, setting stacks to an odd number avoids a "band" around the equator, making things look smoother
101void LLRenderSphere::prerender()
102{
103 // Create a series of display lists for different LODs
104 mDList[0] = glGenLists(1);
105 glNewList(mDList[0], GL_COMPILE);
106 drawSolidSphere(1.0, 30, 20);
107 glEndList();
108
109 mDList[1] = glGenLists(1);
110 glNewList(mDList[1], GL_COMPILE);
111 drawSolidSphere(1.0, 20, 15);
112 glEndList();
113
114 mDList[2] = glGenLists(1);
115 glNewList(mDList[2], GL_COMPILE);
116 drawSolidSphere(1.0, 12, 8);
117 glEndList();
118
119 mDList[3] = glGenLists(1);
120 glNewList(mDList[3], GL_COMPILE);
121 drawSolidSphere(1.0, 8, 5);
122 glEndList();
123}
124
125void LLRenderSphere::cleanupGL()
126{
127 for (S32 detail = 0; detail < 4; detail++)
128 {
129 glDeleteLists(mDList[detail], 1);
130 mDList[detail] = 0;
131 }
132
133 if (gQuadObj2)
134 {
135 gluDeleteQuadric(gQuadObj2);
136 gQuadObj2 = NULL;
137 }
138}
139
140// Constants here are empirically derived from my eyeballs, JNC
141//
142// The toughest adjustment is the cutoff for the lowest LOD
143// Maybe we should have more LODs at the low end?
144void LLRenderSphere::render(F32 pixel_area)
145{
146 S32 level_of_detail;
147
148 if (pixel_area > 10000.f)
149 {
150 level_of_detail = 0;
151 }
152 else if (pixel_area > 800.f)
153 {
154 level_of_detail = 1;
155 }
156 else if (pixel_area > 100.f)
157 {
158 level_of_detail = 2;
159 }
160 else
161 {
162 level_of_detail = 3;
163 }
164 glCallList(mDList[level_of_detail]);
165}
166
167
168void LLRenderSphere::render()
169{
170 glCallList(mDList[0]);
171}