---
name: mesh_gpu
kind: function
lang: cpp
domain: gfx
version: "1.0.0"
purity: impure
signature: "MeshGpu mesh_gpu_upload(const Mesh&); void mesh_gpu_destroy(MeshGpu&)"
description: "Sube un Mesh CPU a OpenGL como VAO + VBO interleaved (pos.xyz, normal.xyz) + EBO uint32. Layout: location 0 = a_pos vec3, location 1 = a_normal vec3, stride 6 floats."
tags: [opengl, mesh, vao, vbo, ebo, gpu, gfx]
uses_functions: ["gl_loader_cpp_gfx", "mesh_obj_load_cpp_gfx"]
uses_types: []
returns: []
returns_optional: false
error_type: "error_go_core"
imports: [GL/gl.h, GL/glext.h]
tested: false
tests: []
test_file_path: ""
file_path: "cpp/functions/gfx/mesh_gpu.cpp"
framework: opengl
params:
  - name: mesh
    desc: "Mesh CPU con positions/normals (mismo length, stride 3) e indices uint32. Si esta vacio o invalido, upload devuelve MeshGpu{} (ok()==false)."
  - name: mesh_gpu
    desc: "MeshGpu (vao/vbo/ebo, index_count). destroy libera todo y pone IDs a 0."
output: "mesh_gpu_upload: MeshGpu listo para draw con glDrawElements(GL_TRIANGLES, index_count, GL_UNSIGNED_INT, 0). Si !ok(), no hubo upload."
---

# mesh_gpu

CRUD GPU minimal para `Mesh`. Asume contexto OpenGL 3.3+ activo.

## Layout de attribs

```glsl
#version 330 core
layout(location = 0) in vec3 a_pos;
layout(location = 1) in vec3 a_normal;
```

Stride = `6 * sizeof(float)`, sin padding.

## Uso tipico

```cpp
auto cpu = fn::gfx::mesh_obj_load("model.obj");
auto gpu = fn::gfx::mesh_gpu_upload(cpu);
if (!gpu.ok()) { /* falla */ return; }

// Draw:
glUseProgram(prog);
glBindVertexArray(gpu.vao);
glDrawElements(GL_TRIANGLES, gpu.index_count, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);

// Cleanup:
fn::gfx::mesh_gpu_destroy(gpu);
```

## Validacion de input

`mesh_gpu_upload` exige que `mesh.normals.size() == mesh.positions.size()`. `mesh_obj_parse` siempre genera normales (per-face si faltan) → invariante natural.

## Notas

- Indices son `GL_UNSIGNED_INT` (32-bit) para soportar meshes grandes sin tener que decidir formato dinamicamente.
- `GL_STATIC_DRAW`: el assumption es que la malla no cambia post-upload. Si necesitas streaming, crear otro helper con `GL_DYNAMIC_DRAW`.
