feat(gfx): mesh_gpu — VAO/VBO/EBO upload para Mesh

mesh_gpu_upload sube positions+normals interleaved (stride 6 floats, location 0=a_pos, location 1=a_normal) + EBO uint32. mesh_gpu_destroy libera todo. GL_STATIC_DRAW (mesh inmutable post-upload). issue 0029
2026-04-25 21:51:10 +02:00
parent 10ac4c74db
commit c5dc63699a
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+---
+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: [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`.