Rendering a sphere unsing glDrawElements and GL_TRIANGLE_STRIP???
Author
Hi all!
I'm trying to make a bank of primitives in my 3d engine including all kind of geometries... plane, cube are pretty easy but when it comes to sphere it's getting a little confusing to index faces!!! I'm looking for any Hint on the subject using either GL_TRIANGLE_STRIP or GL_TRIANGLES... plz no samples using glbegin...
THX
golgoth
Author
nothing wrong with glusphere... but developping with the glut lib is not a part of our plan... since we will eventually use our primitives for dirext x and/or software rendering!
THX
THX
Here are a couple of versions to start you off. Both can be further optimised to remove duplicate vertices at the poles, but I'll leave that to you.
Enigma
EDIT: Small bug in building of StackedSphere.
#include <cmath>#include <vector>#include <gl/glut.h>const float PI = 3.14159265358979323846f;#pragma pack(1)template <typename TYPE>class GeometryVector{ public: GeometryVector(const TYPE x_ = TYPE(), const TYPE y_ = TYPE(), const TYPE z_ = TYPE()); const TYPE x; const TYPE y; const TYPE z;};#pragma pack()template <typename TYPE>GeometryVector<TYPE>::GeometryVector(const TYPE x_, const TYPE y_, const TYPE z_) : x(x_), y(y_), z(z_){}class StackedSphere{ public: StackedSphere(const float radius = 1.0f, const unsigned int stacks = 8, const unsigned int slices = 16); void render() const; private: std::vector<GeometryVector<float> > geometryData_; std::vector<unsigned short> indexData_;};StackedSphere::StackedSphere(const float radius, const unsigned int stacks, const unsigned int slices){ for (unsigned int stackNumber = 0; stackNumber <= stacks; ++stackNumber) { for (unsigned int sliceNumber = 0; sliceNumber < slices; ++sliceNumber) { float theta = stackNumber * PI / stacks; float phi = sliceNumber * 2 * PI / slices; float sinTheta = std::sin(theta); float sinPhi = std::sin(phi); float cosTheta = std::cos(theta); float cosPhi = std::cos(phi); geometryData_.push_back(GeometryVector<float>(radius * cosPhi * sinTheta, radius * sinPhi * sinTheta, radius * cosTheta)); } } for (unsigned int stackNumber = 0; stackNumber < stacks; ++stackNumber) { for (unsigned int sliceNumber = 0; sliceNumber <= slices; ++sliceNumber) { indexData_.push_back((stackNumber * slices) + (sliceNumber % slices)); indexData_.push_back(((stackNumber + 1) * slices) + (sliceNumber % slices)); } }}void StackedSphere::render() const{ glVertexPointer(3, GL_FLOAT, 0, &geometryData_[0]); glEnableClientState(GL_VERTEX_ARRAY); glDrawElements(GL_TRIANGLE_STRIP, indexData_.size(), GL_UNSIGNED_SHORT, &indexData_[0]);}class SpiralSphere{ public: SpiralSphere(const float radius = 1.0f, const unsigned int loops = 8, const unsigned int segmentsPerLoop = 16); void render() const; private: std::vector<GeometryVector<float> > geometryData_; std::vector<unsigned short> indexData_;};SpiralSphere::SpiralSphere(const float radius, const unsigned int loops, const unsigned int segmentsPerLoop){ for (unsigned int loopSegmentNumber = 0; loopSegmentNumber < segmentsPerLoop; ++loopSegmentNumber) { float theta = 0; float phi = loopSegmentNumber * 2 * PI / segmentsPerLoop; float sinTheta = std::sin(theta); float sinPhi = std::sin(phi); float cosTheta = std::cos(theta); float cosPhi = std::cos(phi); geometryData_.push_back(GeometryVector<float>(radius * cosPhi * sinTheta, radius * sinPhi * sinTheta, radius * cosTheta)); } for (unsigned int loopNumber = 0; loopNumber <= loops; ++loopNumber) { for (unsigned int loopSegmentNumber = 0; loopSegmentNumber < segmentsPerLoop; ++loopSegmentNumber) { float theta = (loopNumber * PI / loops) + ((PI * loopSegmentNumber) / (segmentsPerLoop * loops)); if (loopNumber == loops) { theta = PI; } float phi = loopSegmentNumber * 2 * PI / segmentsPerLoop; float sinTheta = std::sin(theta); float sinPhi = std::sin(phi); float cosTheta = std::cos(theta); float cosPhi = std::cos(phi); geometryData_.push_back(GeometryVector<float>(radius * cosPhi * sinTheta, radius * sinPhi * sinTheta, radius * cosTheta)); } } for (unsigned int loopSegmentNumber = 0; loopSegmentNumber < segmentsPerLoop; ++loopSegmentNumber) { indexData_.push_back(loopSegmentNumber); indexData_.push_back(segmentsPerLoop + loopSegmentNumber); } for (unsigned int loopNumber = 0; loopNumber < loops; ++loopNumber) { for (unsigned int loopSegmentNumber = 0; loopSegmentNumber < segmentsPerLoop; ++loopSegmentNumber) { indexData_.push_back(((loopNumber + 1) * segmentsPerLoop) + loopSegmentNumber); indexData_.push_back(((loopNumber + 2) * segmentsPerLoop) + loopSegmentNumber); } }}void SpiralSphere::render() const{ glVertexPointer(3, GL_FLOAT, 0, &geometryData_[0]); glEnableClientState(GL_VERTEX_ARRAY); glDrawElements(GL_TRIANGLE_STRIP, indexData_.size(), GL_UNSIGNED_SHORT, &indexData_[0]);}StackedSphere sphere1(4, 8, 16);SpiralSphere sphere2(4, 8, 16);int r = 0;void reshape(int width, int height){ if (height == 0) { height = 1; } glMatrixMode(GL_PROJECTION); glLoadIdentity(); glViewport(0, 0, width, height); gluPerspective(45.0f, GLfloat(width) / GLfloat(height), 0.1f, 50.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity();}void display(){ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); glTranslatef(0, 0, -25); glPushMatrix(); glTranslatef(-5, 0, 0); glRotatef(r, 0, 1, 0); sphere1.render(); glPopMatrix(); glPushMatrix(); glTranslatef(5, 0, 0); glRotatef(r, 0, 1, 0); sphere2.render(); glPopMatrix(); glutSwapBuffers(); r++;}int main(int argc, char** argv){ glutInit(&argc, argv); glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA); glutInitWindowPosition(0, 0); glutInitWindowSize(512,512); glutCreateWindow("Sphere Test"); glutReshapeFunc(reshape); glutDisplayFunc(display); glutIdleFunc(display); glPolygonMode(GL_FRONT, GL_LINE); glPolygonMode(GL_BACK, GL_LINE); glutMainLoop(); return 0;}Enigma
EDIT: Small bug in building of StackedSphere.
Quote:Original post by golgoth
nothing wrong with glusphere... but developping with the glut lib is not a part of our plan... since we will eventually use our primitives for dirext x and/or software rendering!
THX
REasonable yes, but i must correct you in GLU is not glut and glu is part of the opengl standard.
REasonable yes, but i must correct you in GLU is not glut and glu is part of the opengl standard.
Thats right, it s because we still use gluLookAt... it does a greatjob... but i m looking to replace it...
Golgoth
Thats right, it s because we still use gluLookAt... it does a greatjob... but i m looking to replace it...
Golgoth
glu is open source at sgi, you can grab the source to all your favorite funtions and use them individually.
Author
glu is open source at sgi, you can grab the source to all your favorite funtions and use them individually.
Is this what you refering to???
http://pyopengl.sourceforge.net/documentation/manual/gluLookAt.3G.html
i cant find the open source files you mentioned!
Golgoth
Is this what you refering to???
http://pyopengl.sourceforge.net/documentation/manual/gluLookAt.3G.html
i cant find the open source files you mentioned!
Golgoth
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