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use msh_core::Model;
#[derive(Clone, Debug)]
pub struct RenderMesh {
pub vertices: Vec<[f32; 3]>,
pub batch_count: usize,
}
impl RenderMesh {
pub fn triangle_count(&self) -> usize {
self.vertices.len() / 3
}
}
/// Builds an expanded triangle list for a specific LOD/group pair.
///
/// The output is suitable for simple `glDrawArrays(GL_TRIANGLES, ...)` paths.
pub fn build_render_mesh(model: &Model, lod: usize, group: usize) -> RenderMesh {
let mut vertices = Vec::new();
let mut batch_count = 0usize;
for node_index in 0..model.node_count {
let Some(slot_idx) = model.slot_index(node_index, lod, group) else {
continue;
};
let Some(slot) = model.slots.get(slot_idx) else {
continue;
};
let batch_start = usize::from(slot.batch_start);
let batch_end = batch_start.saturating_add(usize::from(slot.batch_count));
if batch_end > model.batches.len() {
continue;
}
for batch in &model.batches[batch_start..batch_end] {
let index_start = usize::try_from(batch.index_start).unwrap_or(usize::MAX);
let index_count = usize::from(batch.index_count);
let index_end = index_start.saturating_add(index_count);
if index_end > model.indices.len() || index_count < 3 {
continue;
}
for &idx in &model.indices[index_start..index_end] {
let final_idx_u64 = u64::from(batch.base_vertex).saturating_add(u64::from(idx));
let Ok(final_idx) = usize::try_from(final_idx_u64) else {
continue;
};
let Some(pos) = model.positions.get(final_idx) else {
continue;
};
vertices.push(*pos);
}
batch_count += 1;
}
}
RenderMesh {
vertices,
batch_count,
}
}
pub fn compute_bounds(vertices: &[[f32; 3]]) -> Option<([f32; 3], [f32; 3])> {
let mut iter = vertices.iter();
let first = iter.next()?;
let mut min_v = *first;
let mut max_v = *first;
for v in iter {
for i in 0..3 {
if v[i] < min_v[i] {
min_v[i] = v[i];
}
if v[i] > max_v[i] {
max_v[i] = v[i];
}
}
}
Some((min_v, max_v))
}
#[cfg(test)]
mod tests;
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