void Terrain::RenewNodes(const vec3& viewpoint, const QuadTree<TerrainNode>::Iterator& node)
{
//Check if this node must be enabled using morph-factor
float sz = static_cast<float>(node.LayerSize());
float l = node.Offset().x / sz, r = (node.Offset().x + 1) / sz;
float u = node.Offset().y / sz, d = (node.Offset().y + 1) / sz;
vec3 rel_pos = vec3(inverse(GetModelMatrix()) * vec4(viewpoint, 1.0f));
rel_pos.x = ClosestSegmentPoint(rel_pos.x, l, r);
rel_pos.y = ClosestSegmentPoint(rel_pos.y, node->heights.x, node->heights.y);
rel_pos.z = ClosestSegmentPoint(rel_pos.z, u, d);
if (length(rel_pos)*length(rel_pos) /
(1.0f + node->heights.y - node->heights.x) /
(r - l) / (d - u) > 5.0f ||
node.Level() == maxLOD)
{
//This node is probably enabled
}
else
{
//This node is not enabled
//continue checking its children
DisableNodes(node);
RenewNodes(viewpoint, node.Child(1));
RenewNodes(viewpoint, node.Child(0));
RenewNodes(viewpoint, node.Child(3));
RenewNodes(viewpoint, node.Child(2));
}
}
vec2 Terrain::LoadVertices(
const QuadTree<TerrainNode>::Iterator& node,
const Image& hmap
)
{
//Setup vertex data
vec2 res = vec2(1.0f, 0.0f);
int verticesCount = (lodResolution + 1) * (lodResolution + 1);
vector<vec3> vertices(verticesCount), colors(verticesCount);
float deltaX = 1.0f / node.LayerSize() / lodResolution;
float deltaY = 1.0f / node.LayerSize() / lodResolution;
float x = node.OffsetFloat().x;
for (int i = 0; i <= lodResolution; i++, x += deltaX)
{
float y = node.OffsetFloat().y;
for (int j = 0; j <= lodResolution; j++, y += deltaY)
{
float h = hmap[vec2(x, y)].x;
res = UniteSegments(res, vec2(h));
vertices[i*lodResolution + i + j] = vec3(x, h, y);
colors[i*lodResolution + i + j] = vec3(0.2f, 0.2f + h, 0.4f - h);
}
}
// VAO allocation
glGenVertexArrays(1, &node->vaoID);
// VAO setup
glBindVertexArray(node->vaoID);
// VBOs allocation
glGenBuffers(2, node->vboID);
// VBOs setup
// vertices buffer
glBindBuffer(GL_ARRAY_BUFFER, node->vboID[0]);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * 3 * sizeof(GLfloat), vertices.data(), GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), 0);
glEnableVertexAttribArray(0);
// colors buffer
glBindBuffer(GL_ARRAY_BUFFER, node->vboID[1]);
glBufferData(GL_ARRAY_BUFFER, colors.size() * 3 * sizeof(GLfloat), colors.data(), GL_STATIC_DRAW);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), 0);
glEnableVertexAttribArray(1);
// indices buffer
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, GetIndicesBufferID());
OPENGL_CHECK_FOR_ERRORS();
// release vertex data
vertices.clear();
colors.clear();
if (node.Level() < maxLOD)
{
for (int i : {0, 1, 2, 3})
res = UniteSegments(res, LoadVertices(node.Add(i), hmap));
}
node->heights = res;
return res;
}
