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/**
* @file llrendersphere.cpp
* @brief implementation of the LLRenderSphere class.
*
* $LicenseInfo:firstyear=2001&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
// 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 "linden_common.h"
#include "llrendersphere.h"
#include "llerror.h"
#include "llglheaders.h"
GLUquadricObj *gQuadObj2 = NULL;
LLRenderSphere 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);
}
// 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 LLRenderSphere::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 LLRenderSphere::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 LLRenderSphere::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;
}
glCallList(mDList[level_of_detail]);
}
void LLRenderSphere::render()
{
glCallList(mDList[0]);
}
inline LLVector3 polar_to_cart(F32 latitude, F32 longitude)
{
return LLVector3(sin(F_TWO_PI * latitude) * cos(F_TWO_PI * longitude),
sin(F_TWO_PI * latitude) * sin(F_TWO_PI * longitude),
cos(F_TWO_PI * latitude));
}
void LLRenderSphere::renderGGL()
{
S32 const LATITUDE_SLICES = 20;
S32 const LONGITUDE_SLICES = 30;
if (mSpherePoints.empty())
{
mSpherePoints.resize(LATITUDE_SLICES + 1);
for (S32 lat_i = 0; lat_i < LATITUDE_SLICES + 1; lat_i++)
{
mSpherePoints[lat_i].resize(LONGITUDE_SLICES + 1);
for (S32 lon_i = 0; lon_i < LONGITUDE_SLICES + 1; lon_i++)
{
F32 lat = (F32)lat_i / LATITUDE_SLICES;
F32 lon = (F32)lon_i / LONGITUDE_SLICES;
mSpherePoints[lat_i][lon_i] = polar_to_cart(lat, lon);
}
}
}
gGL.begin(LLRender::TRIANGLES);
for (S32 lat_i = 0; lat_i < LATITUDE_SLICES; lat_i++)
{
for (S32 lon_i = 0; lon_i < LONGITUDE_SLICES; lon_i++)
{
gGL.vertex3fv(mSpherePoints[lat_i][lon_i].mV);
gGL.vertex3fv(mSpherePoints[lat_i][lon_i+1].mV);
gGL.vertex3fv(mSpherePoints[lat_i+1][lon_i].mV);
gGL.vertex3fv(mSpherePoints[lat_i+1][lon_i].mV);
gGL.vertex3fv(mSpherePoints[lat_i][lon_i+1].mV);
gGL.vertex3fv(mSpherePoints[lat_i+1][lon_i+1].mV);
}
}
gGL.end();
}
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