OpenSubdiv/opensubdiv/osd/glVertexBuffer.cpp

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#include "../osd/glVertexBuffer.h"

#include "../osd/opengl.h"

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

OsdGLVertexBuffer::OsdGLVertexBuffer(int numElements, int numVertices)
    : _numElements(numElements),
      _numVertices(numVertices),
      _vbo(0)
{
}

OsdGLVertexBuffer::~OsdGLVertexBuffer() {

    glDeleteBuffers(1, &_vbo);
}

OsdGLVertexBuffer *
OsdGLVertexBuffer::Create(int numElements, int numVertices) {

    OsdGLVertexBuffer *instance =
        new OsdGLVertexBuffer(numElements, numVertices);
    if (instance->allocate()) return instance;
    delete instance;
    return 0;
}

void
OsdGLVertexBuffer::UpdateData(const float *src, int startVertex, int numVertices) {

    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
    int size = numVertices * _numElements * sizeof(float);
    glBufferSubData(GL_ARRAY_BUFFER, startVertex * _numElements * sizeof(float), size, src);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

int
OsdGLVertexBuffer::GetNumElements() const {

    return _numElements;
}

int
OsdGLVertexBuffer::GetNumVertices() const {

    return _numVertices;
}

GLuint
OsdGLVertexBuffer::BindVBO() {

    return _vbo;
}

bool
OsdGLVertexBuffer::allocate() {
    
    int size = _numElements * _numVertices * sizeof(float);
    GLint prev = 0;

    glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &prev);
    glGenBuffers(1, &_vbo);
    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
    glBufferData(GL_ARRAY_BUFFER, size, 0, GL_STREAM_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, prev);

//    if (glGetError() != GL_NO_ERROR) return false;
    return true;
}

} // end namespace OPENSUBDIV_VERSION
} // end namespace OpenSubdiv