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#include <cmath>
#include <vector>
#include <iostream>
#include <glm/glm.hpp>
#include "Sphere.h"
using namespace std;
Sphere::Sphere() {
init(48);
}
Sphere::Sphere(int prec) { // prec is precision, or number of slices
init(prec);
}
float Sphere::toRadians(float degrees) { return (degrees*2.0f*3.14159f)/360.0f; }
void Sphere::init(int prec) {
numVertices = (prec+1)*(prec+1);
numIndices = prec*prec*6;
for(int i = 0; i<numVertices; i++) { vertices.push_back(glm::vec3()); } // std::vector::push_back()
for(int i = 0; i<numVertices; i++) { texCoords.push_back(glm::vec2()); } // inserts new element at
for(int i = 0; i<numVertices; i++) { normals.push_back(glm::vec3()); } // the end of a vector and
for(int i = 0; i<numIndices; i++) { indices.push_back(0); } // increases the vector size by 1
// calculate triangle vertices
for(int i = 0; i<=prec; i++) {
for(int j = 0; j<=prec; j++) {
float y = (float)cos(toRadians(180.0f-i*180.0f/prec));
float x = -(float)cos(toRadians(j*360.0f/prec))*(float)abs(cos(asin(y)));
float z = (float)sin(toRadians(j*360.0f/prec))*(float)abs(cos(asin(y)));
vertices[i*(prec+1)+j] = glm::vec3(x,y,z);
texCoords[i*(prec+1)+j] = glm::vec2(((float)j/prec),((float)i/prec));
normals[i*(prec+1)+j] = glm::vec3(x,y,z);
}
}
// calculate triangle indices
for(int i = 0; i<prec; i++) {
for(int j = 0; j<prec; j++) {
indices[6*(i*prec+j)+0] = i*(prec+1)+j;
indices[6*(i*prec+j)+1] = i*(prec+1)+j+1;
indices[6*(i*prec+j)+2] = (i+1)*(prec+1)+j;
indices[6*(i*prec+j)+3] = i*(prec+1)+j+1;
indices[6*(i*prec+j)+4] = (i+1)*(prec+1)+j+1;
indices[6*(i*prec+j)+5] = (i+1)*(prec+1)+j;
}
}
}
// accessors
int Sphere::getNumVertices() { return numVertices; }
int Sphere::getNumIndices() { return numIndices; }
std::vector<int> Sphere::getIndices() { return indices; }
std::vector<glm::vec3> Sphere::getVertices() { return vertices; }
std::vector<glm::vec2> Sphere::getTexCoords() { return texCoords; }
std::vector<glm::vec3> Sphere::getNormals() { return normals; }