58 lines
1.4 KiB
C++
58 lines
1.4 KiB
C++
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#include "orbit.hpp"
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#include "glm/gtx/quaternion.hpp"
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Orbit::Orbit(int vertexCount, glm::vec3 up)
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{
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const float pi = 3.14159265359;
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const glm::vec3 worldUp = glm::vec3(0.0, 1.0, 0.0);
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// Compute the rotation between world 'up' and our defined up
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glm::quat rot = glm::rotation(worldUp, normalize(up));
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for (int i = 0; i < vertexCount; i++)
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{
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float a = (float)i / (float)vertexCount;
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a *= 2.0 * pi;
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glm::vec3 v = glm::vec3(cos(a), 0.0, sin(a));
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// Rotate generated point to align with new up vector
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v = rot * v;
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_vertices.push_back(v.x);
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_vertices.push_back(v.y);
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_vertices.push_back(v.z);
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}
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glGenVertexArrays(1, &_vao);
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glGenBuffers(1, &_vbo);
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glBindVertexArray(_vao);
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glBindBuffer(GL_ARRAY_BUFFER, _vbo);
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size_t vboBufferSize = _vertices.size() * sizeof(float);
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glBufferData(GL_ARRAY_BUFFER, vboBufferSize, &_vertices[0], GL_STATIC_DRAW);
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glEnableVertexAttribArray(0);
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glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
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glBindBuffer(GL_ARRAY_BUFFER, 0);
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glBindVertexArray(0);
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}
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void Orbit::render()
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{
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glBindVertexArray(_vao);
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glBindBuffer(GL_ARRAY_BUFFER, _vbo);
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glDrawArrays(GL_LINE_LOOP, 0, _vertices.size() / 3);
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}
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Orbit::~Orbit()
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{
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glDeleteVertexArrays(1, &_vao);
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glDeleteBuffers(1, &_vbo);
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}
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