/**
Compute position on the curve in time t.
*/
glm::vec3 evaluateClosedCurve(Curve *curve,const float t) {
glm::vec3 result(0.0, 0.0, 0.0);
int i = (int)t;
result = evaluateCurveSegment(curve->points[(i-1) % curve->size],curve->points[(i) % curve->size],curve->points[(i+1) % curve->size],curve->points[(i+2) % curve->size],(float)(t-i));
return result;
}
SplineSegmentNode::SplineSegmentNode(const char * name, SceneNode * parent): SceneNode(name, parent)
{
if(m_program == 0)
{
std::vector<GLuint> shaderList;
// Push vertex shader and fragment shader
shaderList.push_back(pgr::createShader(GL_VERTEX_SHADER, strVertexShader ));
shaderList.push_back(pgr::createShader(GL_FRAGMENT_SHADER, strFragmentShader));
// Create the program with two shaders
m_program = pgr::createProgram(shaderList);
m_PVMmatrixLoc = glGetUniformLocation( m_program, "PVMmatrix");
m_colLoc = glGetUniformLocation( m_program, "color");
m_posLoc = glGetAttribLocation( m_program, "position");
}
if(m_vertexArrayObject == 0)
{
const size_t resoulution = 10; // number of samples per parameter step
m_numberOfCurveSamples = resoulution * curveTestSize; // samples of the drawn curve
glGenBuffers(1, &m_vertexBufferObject);
glBindBuffer(GL_ARRAY_BUFFER, m_vertexBufferObject);
// reserve space for control points + the curve
glBufferData(GL_ARRAY_BUFFER, (curveTestSize + m_numberOfCurveSamples + 4) * sizeof(vec3), NULL, GL_STATIC_DRAW); // 4 for tangents
// put given control points first
glBufferSubData(GL_ARRAY_BUFFER, 0, curveTestSize * sizeof(vec3), curveTestPoints );
// put computed curve points after
GLintptr offset = curveTestSize * sizeof(vec3);
for( unsigned i = 0; i < m_numberOfCurveSamples; i++ )
{
float t = (float)i/m_numberOfCurveSamples;
vec3 position = evaluateCurveSegment( curveTestPoints[0], curveTestPoints[1], curveTestPoints[2], curveTestPoints[3], t); // one point along the curve for parameter t
glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(vec3), value_ptr(position) );
offset += sizeof(vec3);
}
// tangent endpoints
vec3 t0 = (curveTestPoints[2] - curveTestPoints[0]) * 0.2f;
vec3 t1 = (curveTestPoints[3] - curveTestPoints[1]) * 0.2f;
glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(vec3), value_ptr(curveTestPoints[1]-t0) ); offset += sizeof(vec3);
glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(vec3), value_ptr(curveTestPoints[1]+t0) ); offset += sizeof(vec3);
glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(vec3), value_ptr(curveTestPoints[2]-t1) ); offset += sizeof(vec3);
glBufferSubData(GL_ARRAY_BUFFER, offset, sizeof(vec3), value_ptr(curveTestPoints[2]+t1) ); offset += sizeof(vec3);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glGenVertexArrays(1, &m_vertexArrayObject );
glBindVertexArray( m_vertexArrayObject );
glBindBuffer(GL_ARRAY_BUFFER, m_vertexBufferObject);
// Control points folowed by the points along the curve
glEnableVertexAttribArray(m_posLoc);
glVertexAttribPointer(m_posLoc, 3, GL_FLOAT, GL_FALSE, 0, 0);
glBindVertexArray( 0 );
}
}
