OpenSubdiv/examples/simpleCpu/simpleCpuSubdivision.cpp

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// CPU Subdivision with OpenSubdiv
// -------------------------------
// In this example program, we will setup an OpenGL application that uses OSD to
// subdivide an animated mesh. It is intended to be as simple as possible and
// not necessarily efficient. It is also intended as a learning tool for
// understanding the OSD internals. Unlike the other OSD examples, the common
// code infrastructure has been removed for clarity.
//
// ### Program Structure
//
// This example program is structured as follows:
//
// 1. Setup static mesh topology (OsdHbrMesh)
// 2. Convert the topology into a subdividable mesh (OsdMesh)
// 3. On each frame:
// * Animate the coarse mesh points and update the OsdMesh
// * Subdivide the updated mesh
// * Draw the subdivided mesh and wire frame
//
// If you are completely new to OSD, you should read the following sections to
// get a basic understanding of how it works.
//
// ### OSD Architecture Basics
// As a client, you will primarily be interacting with the Osd and Hbr classes,
// however it's good to be aware of all three layers. The following describes
// these layers from lowest level (Hbr) to highest (Osd):
//
// **Hbr: Halfedge Boundary Representation.**
// This layer represents the mesh topology as meshes, vertices and edges. It is
// the core that provides the structure for subdivision and provides an
// abstraction for dealing with topology in a type-agnostic way (i.e. everything
// is templated).
//
// **Far: Feature Adaptive Representation.**
// Far uses hbr to create and cache fast run time data structures for table
// driven subdivision. Feature-adaptive refinement logic is used to adaptively
// refine coarse topology only as much as needed. The FarMesh does hold vertex
// objects but the topology has been baked into FarSubdivisionTables. It also
// provides the underpinnings for generic dispatch of subdivision evaluation, so
// subdivision can be preformed with different mechanisms (GLSL, Cuda, etc.),
// the concrete implementations are specified at the next layer up.
//
// **Osd: Open Subdiv.**
// Osd contains client level code that uses Far to create concrete instances of
// meshes and compute patch CVs with different back ends for table driven
// subdivision. Currently, the following are supported in Osd:
//
// * CPU / C++ with single or multiple threads
// * GLSL kernels with transform feedback into VBOs
// * OpenCL kernels
// * CUDA kernels
//
// The amount of hardware specific computation code is small, ~300 lines of code,
// so it isn't a large effort to support multiple different ones for different
// clients. In the future, it is conceivable that additional dispatchers will be
// developed to target mobile devices.
//
/*
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(B) If you bring a patent claim against any contributor over
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patent license from such contributor to the software ends
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(D) If you distribute any portion of the software in source
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complete copy of this license with your distribution. If you
distribute any portion of the software in compiled or object
code form, you may only do so under a license that complies
with this license.
(E) The software is licensed "as-is." You bear the risk of
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To the extent permitted under your local laws, the contributors
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*/
// ### Helper Includes
// Vector algebra and common GL machinations that have been isolated for
// clarity of the core OSD code.
//
#include "glhelpers.h"
//
// ### OpenSubdiv Includes
// The mutex header provides a cross platform mutex implementation; the vertex
// and mesh headers provide abstract representations of verts and meshes; the
// element array buffer provides an abstract representation of an index buffer;
// and finally, the cpu dispatcher is how subdivision work is dispatched to the
// CPU.
//
#include <osd/mutex.h>
#include <hbr/mesh.h>
#include <hbr/face.h>
#include <hbr/subdivision.h>
#include <hbr/catmark.h>
#include <osd/vertex.h>
#include <osd/mesh.h>
#include <osd/elementArrayBuffer.h>
#include <osd/cpuDispatcher.h>
//
// ### Global Variables & Declarations
//
// The screen width & height; current frame for animation; and the desired
// subdivision level.
//
int g_width = 0,
g_height = 0,
g_frame = 0,
g_level = 4;
//
// A center point for the view matrix and the object size for framing
//
float g_center[3] = {0.0f, 0.0f, 0.0f},
g_size = 0.0f;
//
// The OSD state: a mesh, vertex buffer and element array
//
OpenSubdiv::OsdMesh * g_osdmesh = 0;
OpenSubdiv::OsdVertexBuffer* g_vertexBuffer = 0;
OpenSubdiv::OsdElementArrayBuffer *g_elementArrayBuffer = 0;
//
// The coarse mesh positions and normals are saved externally and deformed
// during playback.
//
std::vector<float> g_orgPositions,
g_normals;
//
// Forward declarations. These functions will be described below as they are
// defined.
//
void idle();
void reshape(int width, int height);
void createOsdMesh(int level, int kernel);
void display();
void updateGeom();
static void calcNormals(OpenSubdiv::OsdHbrMesh * mesh,
std::vector<float> const & pos,
std::vector<float> & result );
//
// ### The main program entry point
//
// register the Osd CPU kernel,
// call createOsdMesh (see below), init glew and one-time GL state and enter the
// main glut loop.
//
void initOsd()
{
initGL();
//
// Dispatchers are created from a kernel enumeration via the factory pattern,
// calling register here ensures that the CPU dispatcher will be available
// for construction when it is requested via the kCPU enumeration inside the
// function createOsdMesh.
//
OpenSubdiv::OsdCpuKernelDispatcher::Register();
//
// The following method will populate the g_osdMesh object, which will
// contain the precomputed subdivision tables.
//
createOsdMesh(g_level,
OpenSubdiv::OsdKernelDispatcher::kCPU);
}
//
// ### Construct the OSD Mesh
// Here is where the real meat of the OSD setup happens. The mesh topology is
// created and stored for later use. Actual subdivision happens in updateGeom
// which gets called at the end of this function and on frame change.
//
void
createOsdMesh(int level, int kernel)
{
//
// Setup an OsdHbr mesh based on the desired subdivision scheme
//
static OpenSubdiv::HbrCatmarkSubdivision<OpenSubdiv::OsdVertex> _catmark;
OpenSubdiv::OsdHbrMesh * hmesh(new OpenSubdiv::OsdHbrMesh(&_catmark));
//
// Now that we have a mesh, we need to add verticies and define the topology.
// Here, we've declared the raw vertex data in-line, for simplicity
//
float verts[] = { 0.000000f, -1.414214f, 1.000000f,
1.414214f, 0.000000f, 1.000000f,
-1.414214f, 0.000000f, 1.000000f,
0.000000f, 1.414214f, 1.000000f,
-1.414214f, 0.000000f, -1.000000f,
0.000000f, 1.414214f, -1.000000f,
0.000000f, -1.414214f, -1.000000f,
1.414214f, 0.000000f, -1.000000f
};
//
// The cube faces are also in-lined, here they are specified as quads
//
int faces[] = {
0,1,3,2,
2,3,5,4,
4,5,7,6,
6,7,1,0,
1,7,5,3,
6,0,2,4
};
//
// Record the original vertex positions and add verts to the mesh.
//
// OsdVertex is really just a place holder, it doesn't care what the
// position of the vertex is, it's just being used here as a means of
// defining the mesh topology.
//
for (unsigned i = 0; i < sizeof(verts)/sizeof(float); i += 3) {
g_orgPositions.push_back(verts[i+0]);
g_orgPositions.push_back(verts[i+1]);
g_orgPositions.push_back(verts[i+2]);
OpenSubdiv::OsdVertex vert;
hmesh->NewVertex(i/3, vert);
}
//
// Now specify the actual mesh topology by processing the faces array
//
const unsigned VERTS_PER_FACE = 4;
for (unsigned i = 0; i < sizeof(faces)/sizeof(int); i += VERTS_PER_FACE) {
//
// Do some sanity checking. It is a good idea to keep this in your
// code for your personal sanity as well.
//
// Note that this loop is not changing the HbrMesh, it's purely validating
// the topology that is about to be created below.
//
for (unsigned j = 0; j < VERTS_PER_FACE; j++) {
OpenSubdiv::OsdHbrVertex * origin = hmesh->GetVertex(faces[i+j]);
OpenSubdiv::OsdHbrVertex * destination = hmesh->GetVertex(faces[i+((j+1)%VERTS_PER_FACE)]);
OpenSubdiv::OsdHbrHalfedge * opposite = destination->GetEdge(origin);
if(origin==NULL || destination==NULL) {
std::cerr <<
" An edge was specified that connected a nonexistent vertex"
<< std::endl;
exit(1);
}
if(origin == destination) {
std::cerr <<
" An edge was specified that connected a vertex to itself"
<< std::endl;
exit(1);
}
if(opposite && opposite->GetOpposite() ) {
std::cerr <<
" A non-manifold edge incident to more than 2 faces was found"
<< std::endl;
exit(1);
}
if(origin->GetEdge(destination)) {
std::cerr <<
" An edge connecting two vertices was specified more than once."
" It's likely that an incident face was flipped"
<< std::endl;
exit(1);
}
}
//
// Now, create current face given the number of verts per face and the
// face index data.
//
OpenSubdiv::OsdHbrFace * face = hmesh->NewFace(VERTS_PER_FACE, faces+i, 0);
//
// If you had ptex data, you would set it here, for example
//
/* face->SetPtexIndex(ptexIndex) */
}
//
// Apply some tags to drive the subdivision algorithm. Here we set the
// default boundary interpolation mode along with a corner sharpness. See
// the API and the renderman spec for the full list of available operations.
//
hmesh->SetInterpolateBoundaryMethod( OpenSubdiv::OsdHbrMesh::k_InterpolateBoundaryEdgeOnly );
OpenSubdiv::OsdHbrVertex * v = hmesh->GetVertex(0);
v->SetSharpness(2.7f);
//
// Finalize the mesh object. The Finish() call is a signal to the internals
// that optimizations can be made on the mesh data.
//
hmesh->Finish();
//
// Setup some raw vectors of data. Remember that the actual point values were
// not stored in the OsdVertex, so we keep track of them here instead
//
g_normals.resize(g_orgPositions.size(),0.0f);
calcNormals( hmesh, g_orgPositions, g_normals );
//
// At this point, we no longer need the topological structure of the mesh,
// so we bake it down into subdivision tables by converting the HBR mesh
// into an OSD mesh. Note that this is just storing the initial subdivision
// tables, which will be used later during the actual subdivision process.
//
// Again, no vertex positions are being stored here, the point data will be
// sent to the mesh in updateGeom().
//
g_osdmesh = new OpenSubdiv::OsdMesh();
g_osdmesh->Create(hmesh, level, kernel);
delete hmesh;
//
// Initialize the index and vertex buffers
//
g_elementArrayBuffer = g_osdmesh->CreateElementArrayBuffer(level);
g_vertexBuffer = g_osdmesh->InitializeVertexBuffer(6 /* 3 floats for position,
+
3 floats for normal*/
);
//
// Setup camera positioning based on object bounds. This really has nothing
// to do with OSD.
//
computeCenterAndSize(g_orgPositions, g_center, &g_size);
//
// Finally, make an explicit call to updateGeom() to force creation of the
// initial buffer objects for the first draw call.
//
updateGeom();
//
// The OsdVertexBuffer provides GL identifiers which can be bound in the
// standard way. Here we setup a single VAO and enable points and normals
// as attributes on the vertex buffer and set the index buffer.
//
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glBindBuffer(GL_ARRAY_BUFFER, g_vertexBuffer->GetGpuBuffer());
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, 0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, (float*)12);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_elementArrayBuffer->GetGlBuffer());
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
//
// ### Update Geometry and Subdivide
// This is where the magic happens. Given the initial subdivision table stored
// in the OsdMesh, on every frame we can now send coarse point position updates
// and recompute the subdivided surface based on the coarse animation.
//
void
updateGeom()
{
int nverts = (int)g_orgPositions.size() / 3;
std::vector<float> vertex;
vertex.reserve(nverts*6);
const float *p = &g_orgPositions[0];
const float *n = &g_normals[0];
//
// Apply a simple deformer to the coarse mesh. We save the deformed points
// and normals into a separate buffer to avoid accumulation of error. This
// loop really has nothing to do with OSD.
//
float r = sin(g_frame*0.001f);
for (int i = 0; i < nverts; ++i) {
float move = 0.05f*cosf(p[0]*20+g_frame*0.01f);
float ct = cos(p[2] * r);
float st = sin(p[2] * r);
vertex.push_back(p[0]*ct + p[1]*st);
vertex.push_back(-p[0]*st + p[1]*ct);
vertex.push_back(p[2]);
//
// To be completely accurate, we should deform the normals here too, but
// the original undeformed normals are sufficient for this example
//
vertex.push_back(n[0]);
vertex.push_back(n[1]);
vertex.push_back(n[2]);
p += 3;
n += 3;
}
//
// Send the animated coarse positions and normals to the vertex buffer.
//
g_vertexBuffer->UpdateData(&vertex[0], nverts);
//
// Dispatch subdivision work based on the coarse vertex buffer. At this
// point, the assigned dispatcher will queue up work, potentially in many
// worker threads. If the subdivided data is required for further processing
// a call to Synchronize() will allow you to block until the worker threads
// complete.
//
g_osdmesh->Subdivide(g_vertexBuffer, NULL);
//
// The call to Synchronize() is not actually necessary, it's being used
// here only for illustration.
//
g_osdmesh->Synchronize();
}
//
// ### Calculate Face Normals
// A helper function to calculate face normals. It is included here to illustrate
// how to inspect the coarse mesh, give an HbrMesh pointer.
//
static void
calcNormals(OpenSubdiv::OsdHbrMesh * mesh,
std::vector<float> const & pos,
std::vector<float> & result )
{
//
// Get the number of vertices and faces. Notice the naming convention is
// different between coarse Vertices and Faces. This may change in the
// future (it an artifact of the original renderman code).
//
int nverts = mesh->GetNumVertices();
int nfaces = mesh->GetNumCoarseFaces();
for (int i = 0; i < nfaces; ++i) {
OpenSubdiv::OsdHbrFace * f = mesh->GetFace(i);
float const * p0 = &pos[f->GetVertex(0)->GetID()*3],
* p1 = &pos[f->GetVertex(1)->GetID()*3],
* p2 = &pos[f->GetVertex(2)->GetID()*3];
float n[3];
cross( n, p0, p1, p2 );
for (int j = 0; j < f->GetNumVertices(); j++) {
int idx = f->GetVertex(j)->GetID() * 3;
result[idx ] += n[0];
result[idx+1] += n[1];
result[idx+2] += n[2];
}
}
for (int i = 0; i < nverts; ++i)
normalize(&result[i*3]);
}
//
// ### Draw the Mesh
// Display handles all drawing per frame. We first call the setupForDisplay
// helper method to setup some uninteresting GL state and then bind the mesh
// using the buffers provided by our OSD objects
//
void
display()
{
setupForDisplay(g_width, g_height, g_size, g_center);
//
// Bind the GL vertex and index buffers
//
glBindBuffer(GL_ARRAY_BUFFER, g_vertexBuffer->GetGpuBuffer());
//
// Bind the solid shaded program and draw elements based on the buffer contents
//
bindProgram(g_quadFillProgram);
glDrawElements(GL_LINES_ADJACENCY, g_elementArrayBuffer->GetNumIndices(),
GL_UNSIGNED_INT, NULL);
//
// Draw the wire frame over the solid shaded mesh
//
bindProgram(g_quadLineProgram);
glUniform4f(glGetUniformLocation(g_quadLineProgram, "fragColor"),
0, 0, 0.5, 1);
glDrawElements(GL_LINES_ADJACENCY, g_elementArrayBuffer->GetNumIndices(),
GL_UNSIGNED_INT, NULL);
//
// This isn't strictly necessary, but unbind the GL state
//
glUseProgram(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
//glDisableClientState(GL_VERTEX_ARRAY);
//
// Draw the HUD/status text
//
//glColor3f(1, 1, 1);
drawString(10, 10, "LEVEL = %d", g_level);
drawString(10, 30, "# of Vertices = %d", g_osdmesh->GetFarMesh()->GetNumVertices());
drawString(10, 50, "KERNEL = CPU");
drawString(10, 70, "SUBDIVISION = %s", "CATMARK");
//
// Finish the current frame
//
glFinish();
}