Imported existing code

indra/llrender/llrendersphere.cpp

@@ -0,0 +1,183 @@
+/** 
+ * @file llrendersphere.cpp
+ * @brief implementation of the LLRenderSphere class.
+ *
+ * $LicenseInfo:firstyear=2001&license=viewergpl$
+ * 
+ * Copyright (c) 2001-2009, 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://secondlifegrid.net/programs/open_source/licensing/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://secondlifegrid.net/programs/open_source/licensing/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.
+ * $/LicenseInfo$
+ */
+
+//	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);
+}
+
+
+// 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 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]);
+}