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/**
* @file llsphere.cpp
* @brief implementation of the LLSphere class.
*
* Copyright (c) 2001-2007, Linden Research, Inc.
*
* Second Life Viewer Source Code
* The source code in this file ("Source Code") is provided by Linden Lab
* to you under the terms of the GNU General Public License, version 2.0
* ("GPL"), unless you have obtained a separate licensing agreement
* ("Other License"), formally executed by you and Linden Lab. Terms of
* the GPL can be found in doc/GPL-license.txt in this distribution, or
* online at http://secondlife.com/developers/opensource/gplv2
*
* There are special exceptions to the terms and conditions of the GPL as
* it is applied to this Source Code. View the full text of the exception
* in the file doc/FLOSS-exception.txt in this software distribution, or
* online at http://secondlife.com/developers/opensource/flossexception
*
* By copying, modifying or distributing this software, you acknowledge
* that you have read and understood your obligations described above,
* and agree to abide by those obligations.
*
* ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
* WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
* COMPLETENESS OR PERFORMANCE.
*/
// Sphere creates a set of display lists that can then be called to create
// a lit sphere at different LOD levels. You only need one instance of sphere
// per viewer - then call the appropriate list.
#include "llviewerprecompiledheaders.h"
#include "llsphere.h"
#include "llerror.h"
#include "llvertexbuffer.h"
#include "llglheaders.h"
GLUquadricObj *gQuadObj2 = NULL;
LLSphere gSphere;
void drawSolidSphere(GLdouble radius, GLint slices, GLint stacks);
void drawSolidSphere(GLdouble radius, GLint slices, GLint stacks)
{
if (!gQuadObj2)
{
gQuadObj2 = gluNewQuadric();
if (!gQuadObj2)
{
llwarns << "drawSolidSphere couldn't allocate quadric" << llendl;
return;
}
}
gluQuadricDrawStyle(gQuadObj2, GLU_FILL);
gluQuadricNormals(gQuadObj2, GLU_SMOOTH);
// If we ever changed/used the texture or orientation state
// of quadObj, we'd need to change it to the defaults here
// with gluQuadricTexture and/or gluQuadricOrientation.
gluQuadricTexture(gQuadObj2, GL_TRUE);
gluSphere(gQuadObj2, radius, slices, stacks);
}
// lat = 0 is Z-axis
// lon = 0, lat = 90 at X-axis
void lat2xyz(LLVector3 * result, F32 lat, F32 lon)
{
// Convert a latitude and longitude to x,y,z on a normal sphere and return it in result
F32 r;
result->mV[VX] = (F32) (cos(lon * DEG_TO_RAD) * sin(lat * DEG_TO_RAD));
result->mV[VY] = (F32) (sin(lon * DEG_TO_RAD) * sin(lat * DEG_TO_RAD));
r = (F32) pow(result->mV[VX] * result->mV[VX] + result->mV[VY] * result->mV[VY], 0.5f);
if (r == 1.0f)
{
result->mV[VZ] = 0.0f;
}
else
{
result->mV[VZ] = (F32) pow(1 - r*r, 0.5f);
if (lat > 90.01)
{
result->mV[VZ] *= -1.0;
}
}
}
void lat2xyz_rad(LLVector3 * result, F32 lat, F32 lon)
{
// Convert a latitude and longitude to x,y,z on a normal sphere and return it in result
F32 r;
result->mV[VX] = (F32) (cos(lon) * sin(lat));
result->mV[VY] = (F32) (sin(lon) * sin(lat));
r = (F32) pow(result->mV[VX] * result->mV[VX] + result->mV[VY] * result->mV[VY], 0.5f);
if (r == 1.0f)
result->mV[VZ] = 0.0f;
else
{
result->mV[VZ] = (F32) pow(1 - r*r, 0.5f);
if (lat > F_PI_BY_TWO) result->mV[VZ] *= -1.0;
}
}
// A couple thoughts on sphere drawing:
// 1) You need more slices than stacks, but little less than 2:1
// 2) At low LOD, setting stacks to an odd number avoids a "band" around the equator, making things look smoother
void LLSphere::prerender()
{
// Create a series of display lists for different LODs
mDList[0] = glGenLists(1);
glNewList(mDList[0], GL_COMPILE);
drawSolidSphere(1.0, 30, 20);
glEndList();
mDList[1] = glGenLists(1);
glNewList(mDList[1], GL_COMPILE);
drawSolidSphere(1.0, 20, 15);
glEndList();
mDList[2] = glGenLists(1);
glNewList(mDList[2], GL_COMPILE);
drawSolidSphere(1.0, 12, 8);
glEndList();
mDList[3] = glGenLists(1);
glNewList(mDList[3], GL_COMPILE);
drawSolidSphere(1.0, 8, 5);
glEndList();
}
void LLSphere::cleanupGL()
{
for (S32 detail = 0; detail < 4; detail++)
{
glDeleteLists(mDList[detail], 1);
mDList[detail] = 0;
}
if (gQuadObj2)
{
gluDeleteQuadric(gQuadObj2);
gQuadObj2 = NULL;
}
}
// Constants here are empirically derived from my eyeballs, JNC
//
// The toughest adjustment is the cutoff for the lowest LOD
// Maybe we should have more LODs at the low end?
void LLSphere::render(F32 pixel_area)
{
S32 level_of_detail;
if (pixel_area > 10000.f)
{
level_of_detail = 0;
}
else if (pixel_area > 800.f)
{
level_of_detail = 1;
}
else if (pixel_area > 100.f)
{
level_of_detail = 2;
}
else
{
level_of_detail = 3;
}
LLVertexBuffer::unbind();
glCallList(mDList[level_of_detail]);
}
void LLSphere::render()
{
LLVertexBuffer::unbind();
glCallList(mDList[0]);
}
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