void VertexBuffer::SetAttribPointers()
{
for (Uint8 i = 0; i < MAX_ATTRIBS; i++) {
const auto& attr = m_desc.attrib[i];
const auto offset = reinterpret_cast<const GLvoid*>(m_desc.attrib[i].offset);
switch (attr.semantic) {
case ATTRIB_POSITION:
glVertexPointer(get_num_components(attr.format), get_component_type(attr.format), m_desc.stride, offset);
break;
case ATTRIB_NORMAL:
glNormalPointer(get_component_type(attr.format), m_desc.stride, offset);
break;
case ATTRIB_DIFFUSE:
glColorPointer(get_num_components(attr.format), get_component_type(attr.format), m_desc.stride, offset);
break;
case ATTRIB_UV0:
glTexCoordPointer(get_num_components(attr.format), get_component_type(attr.format), m_desc.stride, offset);
break;
case ATTRIB_NONE:
default:
return;
}
}
}
VertexBuffer::VertexBuffer(const VertexBufferDesc &desc) :
Graphics::VertexBuffer(desc)
{
//update offsets in desc
for (Uint32 i = 0; i < MAX_ATTRIBS; i++) {
if (m_desc.attrib[i].offset == 0)
m_desc.attrib[i].offset = VertexBufferDesc::CalculateOffset(m_desc, m_desc.attrib[i].semantic);
}
//update stride in desc (respecting offsets)
if (m_desc.stride == 0)
{
Uint32 lastAttrib = 0;
while (lastAttrib < MAX_ATTRIBS) {
if (m_desc.attrib[lastAttrib].semantic == ATTRIB_NONE)
break;
lastAttrib++;
}
m_desc.stride = m_desc.attrib[lastAttrib].offset + VertexBufferDesc::GetAttribSize(m_desc.attrib[lastAttrib].format);
}
assert(m_desc.stride > 0);
assert(m_desc.numVertices > 0);
SetVertexCount(m_desc.numVertices);
glGenVertexArrays(1, &m_vao);
glBindVertexArray(m_vao);
glGenBuffers(1, &m_buffer);
//Allocate initial data store
//Using zeroed m_data is not mandatory, but otherwise contents are undefined
glBindBuffer(GL_ARRAY_BUFFER, m_buffer);
const Uint32 dataSize = m_desc.numVertices * m_desc.stride;
m_data = new Uint8[dataSize];
memset(m_data, 0, dataSize);
const GLenum usage = (m_desc.usage == BUFFER_USAGE_STATIC) ? GL_STATIC_DRAW : GL_DYNAMIC_DRAW;
glBufferData(GL_ARRAY_BUFFER, dataSize, m_data, usage);
//Setup the VAO pointers
for (Uint8 i = 0; i < MAX_ATTRIBS; i++) {
const auto& attr = m_desc.attrib[i];
if (attr.semantic == ATTRIB_NONE)
break;
// Tell OpenGL what the array contains
const auto offset = reinterpret_cast<const GLvoid*>(attr.offset);
switch (attr.semantic) {
case ATTRIB_POSITION:
glEnableVertexAttribArray(0); // Enable the attribute at that location
glVertexAttribPointer(0, get_num_components(attr.format), get_component_type(attr.format), GL_FALSE, m_desc.stride, offset);
break;
case ATTRIB_NORMAL:
glEnableVertexAttribArray(1); // Enable the attribute at that location
glVertexAttribPointer(1, get_num_components(attr.format), get_component_type(attr.format), GL_FALSE, m_desc.stride, offset);
break;
case ATTRIB_DIFFUSE:
glEnableVertexAttribArray(2); // Enable the attribute at that location
glVertexAttribPointer(2, get_num_components(attr.format), get_component_type(attr.format), GL_TRUE, m_desc.stride, offset); // only normalise the colours
break;
case ATTRIB_UV0:
glEnableVertexAttribArray(3); // Enable the attribute at that location
glVertexAttribPointer(3, get_num_components(attr.format), get_component_type(attr.format), GL_FALSE, m_desc.stride, offset);
break;
case ATTRIB_NONE:
default:
break;
}
}
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
//Don't keep client data around for static buffers
if (GetDesc().usage == BUFFER_USAGE_STATIC) {
delete[] m_data;
m_data = nullptr;
}
}