The algorithm comes from the relevant part of learn opengl pbr,
and only considers how to port it to osg.
1. How the normal changes from the local coordinate system to the world coordinate system (reverse transposition matrix)
2. The view point is obtained by the robot,
3. The viewpoint uniform pointer is passed to the robot and changed in the robot
In order to illustrate the correctness, first set the viewpoint as the origin, and it is normal when the right arrow key is pressed.
It can be seen that half facing the origin is correct.
After correction,
代码如下：
travel.h
#pragma once
#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#include <osgGA/GUIEventAdapter>
#include <osgViewer/ViewerEventHandlers>
#include <osg/AnimationPath>
#include
#include <osg/PositionAttitudeTransform>
#include <osg/MatrixTransform>
#include <osgGA/CameraManipulator>
#include <osg/matrixd>
class TravelManipulator : public osgGA::CameraManipulator
{
public:
TravelManipulator();
public:
//Set current viewport
virtual void setByMatrix(const osg::Matrixd& matrix);
virtual void setByInverseMatrix(const osg::Matrixd& matrix);
//Get current matrix and inverse matrix
virtual osg::Matrixd getMatrix() const;
virtual osg::Matrixd getInverseMatrix() const;
virtual bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& us);
void ChangePosition(osg::Vec3d& delta);
private:
//viewpoint
osg::Vec3 m_vPosition;
//towards
osg::Vec3 m_vRotation;
//moving step
int m_vStep;
//rotating step
float m_vRotateSpeed;
//暂停
bool _bPause;
public:
//Set eye position to shader
void setEyePosUniform(osg::ref_ptrosg::Uniform camearaPosUniform);
//
osg::ref_ptrosg::Uniform _eyePosUniform;
};
travel.cpp
#include “Travel.h”
TravelManipulator::TravelManipulator()
{
m_vPosition = osg::Vec3(0, 0, 50);
m_vRotation = osg::Vec3(osg::PI_2, 0, 0);
m_vStep = 1.0;
m_vRotateSpeed = 1.0;
_bPause = false;
_eyePosUniform = NULL;
}
void TravelManipulator::setByMatrix(const osg::Matrixd & matrix)
{
}
void TravelManipulator::setByInverseMatrix(const osg::Matrixd & matrix)
{
}
osg::Matrixd TravelManipulator::getMatrix() const
{
osg::Matrixd matTrans;
matTrans.makeTranslate(m_vPosition);
osg::Matrixd matRotate;
matRotate.makeRotate(m_vRotation[0], osg::X_AXIS, m_vRotation[1], osg::Y_AXIS, m_vRotation[2], osg::Z_AXIS);
return matRotate * matTrans;
}
osg::Matrixd TravelManipulator::getInverseMatrix() const
{
osg::Matrixd mat = getMatrix();
return osg::Matrixd::inverse(mat);
}
bool TravelManipulator::handle(const osgGA::GUIEventAdapter & ea, osgGA::GUIActionAdapter & us)
{
switch (ea.getEventType())
{
case osgGA::GUIEventAdapter::KEYDOWN:
{
//if (ea.getKey() ==‘p’)
//{
// _bPause = !_bPause;
//}
//if (_bPause)
{
if ((ea.getKey() == ‘w’) || (ea.getKey() == ‘W’) )
{
ChangePosition(osg::Vec3d(m_vStep * cosf(osg::PI_2 + m_vRotation._v[2]), m_vStep * sinf(osg::PI_2 + m_vRotation._v[2]), 0));
return true;
}
else if ((ea.getKey() == ‘s’) || (ea.getKey() == ‘S’))
{
ChangePosition(osg::Vec3d(-m_vStep * cosf(osg::PI_2 + m_vRotation._v[2]), -m_vStep * sinf(osg::PI_2 + m_vRotation._v[2]), 0));
return true;
}
else if ((ea.getKey() == ‘a’) || (ea.getKey() == ‘A’) )
{
ChangePosition(osg::Vec3d(m_vStep * sinf(osg::PI_2 + m_vRotation._v[2]), -m_vStep * cosf(osg::PI_2 + m_vRotation._v[2]), 0));
return true;
}
else if ((ea.getKey() == ‘d’) || (ea.getKey() == ‘D’) )
{
ChangePosition(osg::Vec3d(-m_vStep * sinf(osg::PI_2 + m_vRotation._v[2]), m_vStep * cosf(osg::PI_2 + m_vRotation._v[2]), 0));
return true;
}
else if ((ea.getKey() == ‘Q’) || (ea.getKey() == ‘q’))
{
ChangePosition(osg::Vec3d(0, 0, 0.2));
return true;
}
else if ((ea.getKey() == ‘E’) || (ea.getKey() == ‘e’))
{
ChangePosition(osg::Vec3d(0, 0, -0.2));
return true;
}
else if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Up)
{
m_vRotation[0] += 0.2;
if (_eyePosUniform)
{
//_eyePosUniform->set(m_vPosition);
}
return true;
}
else if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Down)
{
m_vRotation[0] -= 0.2;
if (_eyePosUniform)
{
//_eyePosUniform->set(m_vPosition);
}
return true;
}
else if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Left)
{
m_vRotation[2] += 0.2;
if (_eyePosUniform)
{
//_eyePosUniform->set(m_vPosition);
}
return true;
}
else if (ea.getKey() == osgGA::GUIEventAdapter::KEY_Right)
{
m_vRotation[2] -= 0.2;
if (_eyePosUniform)
{
_eyePosUniform->set(m_vPosition);
}
return true;
}
}
}
break;
case osgGA::GUIEventAdapter::FRAME:
{
//if (!_bPause)
//{
// //m_vPosition[2] += 1;
//}
}
break;
default:
break;
}
return false;
}
void TravelManipulator::ChangePosition(osg::Vec3d & delta)
{ m_vPosition += delta; } void TravelManipulator::setEyePosUniform(osg::ref_ptrosg::Uniform cameraPosUniform) { _eyePosUniform = camearaPosUniform; } main.cpp //Read through Liblas .las file, and display it in osg, use shader, first specify the use of green in the fragment shader #include <liblas/liblas.hpp> #include #include
#include <osgDB/ReadFile>
#include <osgDB/WriteFile>
#include <osgUtil/Optimizer>
#include <osg/CoordinateSystemNode>
#include <osg/Switch>
#include <osg/Types>
#include <osgText/Text>
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>
#include <osgGA/TrackballManipulator>
#include <osgGA/FlightManipulator>
#include <osgGA/DriveManipulator>
#include <osgGA/KeySwitchMatrixManipulator>
#include <osgGA/StateSetManipulator>
#include <osgGA/AnimationPathManipulator>
#include <osgGA/TerrainManipulator>
#include <osgGA/SphericalManipulator>
#include <osgGA/Device>
#include
#include <osg/Shader>
#include <osg/BlendFunc>
#include <osg/blendColor>
#include <osg/Point>
#include <osg/Shapedrawable>
#include <osgUtil/SmoothingVisitor>
#include “Travel.h”
static const char * vertexShader_PBR =
{
“in vec3 aPos; \n”
“in vec3 aNormal; \n”
“varying vec3 WorldPos; \n”
“varying vec3 Normal; \n”
“uniform mat4 normalMatrix; \n”
“void main() \n”
“{ \n”
" WorldPos = aPos; \n"
" Normal = vec3(normalMatrix * vec4(aNormal,1.0)); \n"
" gl_Position = ftransform(); \n"
“}\n”
};
static const char psShader_PBR =
{
“#version 330 core \n”
“out vec4 FragColor; \n”
“varying vec3 WorldPos; \n”
“varying vec3 Normal; \n”
“uniform vec3 albedo; \n”
“uniform float metallic; \n”
“uniform float roughness; \n”
“uniform float ao; \n”
“uniform vec3 lightPositions[4]; \n”
“uniform vec3 lightColors[4]; \n”
“uniform vec3 camPos; \n”
“const float PI = 3.14159265359; \n”
“float DistributionGGX(vec3 N, vec3 H, float roughness) \n”
“{ \n”
" float a = roughnessroughness; \n"
" float a2 = aa; \n"
" float NdotH = max(dot(N, H), 0.0); \n"
" float NdotH2 = NdotHNdotH; \n"
" float nom = a2; \n"
" float denom = (NdotH2 * (a2 - 1.0) + 1.0); \n"
" denom = PI * denom * denom; \n"
" return nom / denom; \n"
“} \n”
“float GeometrySchlickGGX(float NdotV, float roughness) \n”
“{ \n”
" float r = (roughness + 1.0); \n"
" float k = (r*r) / 8.0; \n"
" float nom = NdotV; \n"
" float denom = NdotV * (1.0 - k) + k; \n"
" return nom / denom; \n"
“} \n”
“float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness) \n”
“{ \n”
" float NdotV = max(dot(N, V), 0.0); \n"
" float NdotL = max(dot(N, L), 0.0); \n"
" float ggx2 = GeometrySchlickGGX(NdotV, roughness); \n"
" float ggx1 = GeometrySchlickGGX(NdotL, roughness); \n"
" return ggx1 * ggx2; \n"
“} \n”
“vec3 fresnelSchlick(float cosTheta, vec3 F0) \n”
“{ \n”
" return F0 + (1.0 - F0) * pow(clamp(1.0 - cosTheta, 0.0, 1.0), 5.0); \n"
“} \n”
“void main() \n”
“{ \n”
" vec3 N = normalize(Normal); \n"
" vec3 V = normalize(camPos - WorldPos); \n"
" vec3 F0 = vec3(0.04); \n"
" F0 = mix(F0, albedo, metallic); \n"
" vec3 Lo = vec3(0.0); \n"
" for (int i = 0; i < 4; ++i) \n"
" { \n"
" vec3 L = normalize(lightPositions[i] - WorldPos); \n"
" vec3 H = normalize(V + L); \n"
" float distance = length(lightPositions[i] - WorldPos); \n"
" float attenuation = 1.0 / (distance * distance); \n"
" vec3 radiance = lightColors[i] * attenuation; \n"
" float NDF = DistributionGGX(N, H, roughness); \n"
" float G = GeometrySmith(N, V, L, roughness); \n"
" vec3 F = fresnelSchlick(clamp(dot(H, V), 0.0, 1.0), F0); \n"
" vec3 numerator = NDF * G * F; \n"
" float denominator = 4.0 * max(dot(N, V), 0.0) * max(dot(N, L), 0.0) + 0.0001; \n"
" vec3 specular = numerator / denominator; \n"
" vec3 kS = F; \n"
" vec3 kD = vec3(1.0) - kS; \n"
" kD *= 1.0 - metallic; \n"
" float NdotL = max(dot(N, L), 0.0); \n"
" Lo += (kD * albedo / PI + specular) * radiance * NdotL; \n"
" } \n"
" vec3 ambient = vec3(0.03) * albedo * ao; \n"
" vec3 color = ambient + Lo; \n"
" color = color / (color + vec3(1.0)); \n"
" color = pow(color, vec3(1.0 / 2.2)); \n"
" FragColor = vec4(color, 1.0); \n"
//" FragColor = vec4(1.0,0.0,0.0, 1.0); \n"
“} \n”
};
osg::ref_ptrosg::Geode CreateSphereGeode()
{
osg::ref_ptrosg::Geode geode = new osg::Geode;
osg::ref_ptrosg::Vec3Array vertices = new osg::Vec3Array(6);
(*vertices)[0].set(0.0f, 0.0f, 1.0f);
(*vertices)[1].set(-0.5f, -0.5f, 0.0f);
(*vertices)[2].set(0.5f, -0.5f, 0.0f);
(*vertices)[3].set(0.5f, 0.5f, 0.0f);
(*vertices)[4].set(-0.5f, 0.5f, 0.0f);
(*vertices)[5].set(0.0f, 0.0f, -1.0f);
osg::ref_ptrosg::DrawElementsUInt indices = new osg::DrawElementsUInt(GL_TRIANGLES, 24);
(*indices)[0] = 0; (*indices)[1] = 1; (*indices)[2] = 2;
(*indices)[3] = 0; (*indices)[4] = 2; (*indices)[5] = 3;
(*indices)[6] = 0; (*indices)[7] = 3; (*indices)[8] = 4;
(*indices)[9] = 0; (*indices)[10] = 4; (*indices)[11] = 1;
(*indices)[12] = 5; (*indices)[13] = 2; (*indices)[14] = 1;
(*indices)[15] = 5; (*indices)[16] = 3; (*indices)[17] = 2;
(*indices)[18] = 5; (*indices)[19] = 4; (*indices)[20] = 3;
(*indices)[21] = 5; (*indices)[22] = 1; (*indices)[23] = 4;
osg::ref_ptrosg::Geometry geom = new osg::Geometry;
geom->setVertexArray(vertices.get());
geom->addPrimitiveSet(indices.get());
osgUtil::SmoothingVisitor::smooth(*geom);
geode->addDrawable(geom);
return geode;
}
osg::ref_ptrosg::Geode renderSphere(osg::Vec3f pos)
{
osg::ref_ptrosg::Geode geode = new osg::Geode;
const unsigned int X_SEGMENTS = 64;
const unsigned int Y_SEGMENTS = 64;
const float PI = 3.14159265359f;
osg::ref_ptrosg::Vec3Array vertices = new osg::Vec3Array;
osg::ref_ptrosg::Vec3Array normalArray = new osg::Vec3Array;
for (unsigned int x = 0; x <= X_SEGMENTS; ++x)
{
for (unsigned int y = 0; y <= Y_SEGMENTS; ++y)
{
float xSegment = (float)x / (float)X_SEGMENTS;
float ySegment = (float)y / (float)Y_SEGMENTS;
float xPos = std::cos(xSegment * 2.0f * PI) * std::sin(ySegment * PI);
float yPos = std::cos(ySegment * PI);
float zPos = std::sin(xSegment * 2.0f * PI) * std::sin(ySegment * PI);
vertices->push_back(osg::Vec3(xPos, yPos, zPos) + pos);
normalArray->push_back(osg::Vec3(xPos, yPos, zPos));
}
}
osg::ref_ptr<osg::DrawElementsUInt> indices = new osg::DrawElementsUInt();
bool oddRow = false;
for (unsigned int y = 0; y < Y_SEGMENTS; ++y)
{
if (!oddRow) // even rows: y == 0, y == 2; and so on
{
for (unsigned int x = 0; x <= X_SEGMENTS; ++x)
{
indices->push_back(y * (X_SEGMENTS + 1) + x);
indices->push_back((y + 1) * (X_SEGMENTS + 1) + x);
}
}
else
{
for (int x = X_SEGMENTS; x >= 0; --x)
{
indices->push_back((y + 1) * (X_SEGMENTS + 1) + x);
indices->push_back(y * (X_SEGMENTS + 1) + x);
}
}
oddRow = !oddRow;
}
int indexCount = static_cast<unsigned int>(indices->size());
indices->setMode(GL_TRIANGLE_STRIP);
osg::ref_ptr<osg::Geometry> geom = new osg::Geometry;
geom->setVertexArray(vertices.get());
geom->addPrimitiveSet(indices.get());
geom->setNormalArray(normalArray, osg::Array::BIND_PER_VERTEX);
geom->setVertexAttribArray(1, vertices, osg::Array::BIND_PER_VERTEX);
geom->setVertexAttribArray(2, normalArray, osg::Array::BIND_PER_VERTEX);
//osgUtil::SmoothingVisitor::smooth(*geom);
geode->addDrawable(geom);
return geode;
}
int main()
{
osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;
osg::ref_ptr<TravelManipulator> manipulator = new TravelManipulator;
viewer->setCameraManipulator(manipulator);
osg::ref_ptr<osg::Uniform> camPosUniform = new osg::Uniform("camPos", osg::Vec3f(0,0,0));
manipulator->setEyePosUniform(camPosUniform);
osg::ref_ptr<osg::Camera> camera = viewer->getCamera();
osg::Matrix viewMatrix = camera->getViewMatrix();
osg::Matrix projMatrix = camera->getProjectionMatrix();
osg::Vec3f eye, center, up;
camera->getViewMatrixAsLookAt(eye, center, up);
//osg::ref_ptr<osg::Uniform> camPosUniform = new osg::Uniform("camPos", eye);
osg::ref_ptr<osg::Uniform> viewMatrixUniform = new osg::Uniform("view", viewMatrix);
osg::ref_ptr<osg::Uniform> projMatrixUniform = new osg::Uniform("projection", projMatrix);
osg::ref_ptr<osg::Group> grp = new osg::Group;
osg::Vec3f albedo(0.5f, 0.0f, 0.0f);
osg::ref_ptr<osg::Uniform> albedoUniform = new osg::Uniform("albedo", albedo);
float ao = 1.0f;
osg::ref_ptr<osg::Uniform> aoUniform = new osg::Uniform("ao", ao);
int nrRows = 7;
int nrColumns = 7;
float spacing = 2.5;
float ballRadius = 1.0f;
osg::ref_ptr<osg::Vec3Array> lightColors = new osg::Vec3Array;
lightColors->push_back(osg::Vec3(300.0f, 300.0f, 300.0f));
lightColors->push_back(osg::Vec3(300.0f, 300.0f, 300.0f));
lightColors->push_back(osg::Vec3(300.0f, 300.0f, 300.0f));
lightColors->push_back(osg::Vec3(300.0f, 300.0f, 300.0f));
osg::ref_ptr<osg::Uniform> lightColorsUniform = new osg::Uniform(osg::Uniform::FLOAT_VEC3, "lightColors", lightColors->size());
for (int i = 0; i < lightColors->size(); i++)
{
lightColorsUniform->setElement(i, lightColors->at(i));
}
osg::ref_ptr<osg::Vec3Array> lightPositions = new osg::Vec3Array;
lightPositions->push_back(osg::Vec3(-10.0f, 10.0f, 10.0f));
lightPositions->push_back(osg::Vec3(10.0f, 10.0f, 10.0f));
lightPositions->push_back(osg::Vec3(-10.0f, -10.0f, 10.0f));
lightPositions->push_back(osg::Vec3(10.0f, -10.0f, 10.0f));
osg::ref_ptr<osg::Uniform> lightPositionsUniform = new osg::Uniform(osg::Uniform::FLOAT_VEC3, "lightPositions", lightPositions->size());
for (int i = 0; i < lightPositions->size(); i++)
{
lightPositionsUniform->setElement(i, lightPositions->at(i));
}
for (int row = 0; row < nrRows; row++)
{
float metallic = row * 1.0 / nrRows;
for (int col = 0; col < nrColumns; col++)
{
float roughness = col * 1.0 / nrColumns;
if (roughness <0.05)
{
roughness = 0.05;
}
if (roughness > 1.0)
{
roughness = 1.0;
}
osg::Vec3 ballCenter(
(col - (nrColumns / 2)) * spacing,
(row - (nrRows / 2)) * spacing,
0.0f);
osg::Matrix worldMatrix = osg::Matrix::translate(ballCenter);
osg::Matrix inverse;
inverse.invert(worldMatrix);
osg::Matrix transPose;
transPose.transpose(inverse);
osg::ref_ptr<osg::Geode> geode = renderSphere(ballCenter);
{
osg::ref_ptr<osg::StateSet> stateset = geode->getOrCreateStateSet();
osg::ref_ptr<osg::Shader> vs = new osg::Shader(osg::Shader::VERTEX, vertexShader_PBR);
osg::ref_ptr<osg::Shader> ps = new osg::Shader(osg::Shader::FRAGMENT, psShader_PBR);
osg::ref_ptr<osg::Program> program = new osg::Program;
program->addBindAttribLocation("aPos", 1);
program->addBindAttribLocation("aNormal", 2);
program->addShader(vs);
program->addShader(ps);
osg::ref_ptr<osg::Uniform> metallicUniform = new osg::Uniform("metallic", metallic);
osg::ref_ptr<osg::Uniform> roughnessUniform = new osg::Uniform("roughness", roughness);
//osg::ref_ptr<osg::Uniform> transposeInverseMatrixUniform = new osg::Uniform("normalMatrix", transPose);
osg::Uniform* transposeInverseMatrixUniform = stateset->getOrCreateUniform("normalMatrix", osg::Uniform::FLOAT_MAT4);
transposeInverseMatrixUniform->set(transPose);
stateset->addUniform(albedoUniform);
stateset->addUniform(metallicUniform);
stateset->addUniform(roughnessUniform);
stateset->addUniform(aoUniform);
stateset->addUniform(lightPositionsUniform);
stateset->addUniform(lightColorsUniform);
stateset->addUniform(transposeInverseMatrixUniform);
stateset->addUniform(viewMatrixUniform);
stateset->addUniform(projMatrixUniform);
stateset->addUniform(camPosUniform);
stateset->setAttribute(program, osg::StateAttribute::ON);
}
grp->addChild(geode);
}
}
grp->addChild(renderSphere(osg::Vec3(-10.0f, 10.0f, 10.0f)));
grp->addChild(renderSphere(osg::Vec3(10.0f, 10.0f, 10.0f)));
grp->addChild(renderSphere(osg::Vec3(-10.0f, -10.0f, 10.0f)));
grp->addChild(renderSphere(osg::Vec3(10.0f, -10.0f, 10.0f)));
viewer->getCamera()->setClearColor(osg::Vec4(0.1f, 0.1f, 0.1f, 1.0f));
viewer->setSceneData(grp);
viewer->run();
return 0;
}