带有 tinyobjloader 的 OpenGL 顶点数组对象
OpenGL vertex array objects with tinyobjloader
为了将现代 openGl 与 tinyobjloader 一起使用，我正在尝试更改 viewer exemple。
我只是更改了 LoadObjAndConvert 函数，添加我在 tutorial 中看到的顶点数组对象，并且不再使用包含所有数据（位置、索引、颜色、uv）的缓冲区对象，因为看起来我们不能再与现代 openGL 一起使用。
结果看起来我的顶点索引不好，模型只渲染了一部分，如果模型只有一个网格（斯坦福兔子），它甚至不会显示。
代码太长，但是和tinyobjloader viewer example一样，所以我只post个不同的函数
这里是修改的LoadObjAndConvert函数（修改的部分在行之间有帮助）：
static bool LoadObjAndConvert(float bmin[3], float bmax[3],
std::vector<DrawObject>* drawObjects,
std::vector<tinyobj::material_t>& materials,
std::map<std::string, GLuint>& textures,
const char* filename) {
tinyobj::attrib_t attrib;
std::vector<tinyobj::shape_t> shapes;
timerutil tm;
tm.start();
std::string base_dir = GetBaseDir(filename);
if (base_dir.empty()) {
base_dir = ".";
}
#ifdef _WIN32
base_dir += "\";
#else
base_dir += "/";
#endif
std::string err;
bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, filename,
base_dir.c_str());
if (!err.empty()) {
std::cerr << err << std::endl;
}
tm.end();
if (!ret) {
std::cerr << "Failed to load " << filename << std::endl;
return false;
}
printf("Parsing time: %d [ms]\n", (int)tm.msec());
printf("# of vertices = %d\n", (int)(attrib.vertices.size()) / 3);
printf("# of normals = %d\n", (int)(attrib.normals.size()) / 3);
printf("# of texcoords = %d\n", (int)(attrib.texcoords.size()) / 2);
printf("# of materials = %d\n", (int)materials.size());
printf("# of shapes = %d\n", (int)shapes.size());
// Append `default` material
materials.push_back(tinyobj::material_t());
for (size_t i = 0; i < materials.size(); i++) {
printf("material[%d].diffuse_texname = %s\n", int(i),
materials[i].diffuse_texname.c_str());
}
// Load diffuse textures
{
for (size_t m = 0; m < materials.size(); m++) {
tinyobj::material_t* mp = &materials[m];
if (mp->diffuse_texname.length() > 0) {
// Only load the texture if it is not already loaded
if (textures.find(mp->diffuse_texname) == textures.end()) {
GLuint texture_id;
int w, h;
int comp;
std::string texture_filename = mp->diffuse_texname;
if (!FileExists(texture_filename)) {
// Append base dir.
texture_filename = base_dir + mp->diffuse_texname;
if (!FileExists(texture_filename)) {
std::cerr << "Unable to find file: " << mp->diffuse_texname
<< std::endl;
exit(1);
}
}
unsigned char* image =
stbi_load(texture_filename.c_str(), &w, &h, &comp, STBI_default);
if (!image) {
std::cerr << "Unable to load texture: " << texture_filename
<< std::endl;
exit(1);
}
std::cout << "Loaded texture: " << texture_filename << ", w = " << w
<< ", h = " << h << ", comp = " << comp << std::endl;
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_2D, texture_id);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
if (comp == 3) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB,
GL_UNSIGNED_BYTE, image);
} else if (comp == 4) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA,
GL_UNSIGNED_BYTE, image);
} else {
assert(0); // TODO
}
glBindTexture(GL_TEXTURE_2D, 0);
stbi_image_free(image);
textures.insert(std::make_pair(mp->diffuse_texname, texture_id));
}
}
}
}
bmin[0] = bmin[1] = bmin[2] = std::numeric_limits<float>::max();
bmax[0] = bmax[1] = bmax[2] = -std::numeric_limits<float>::max();
{
for (size_t s = 0; s < shapes.size(); s++) {
/*-----------------------------------------------------------*/
DrawObject o;// I keep this object for later purpose, texture, etc
//std::vector<float> buffer; // pos(3float), normal(3float), color(3float)
//I replace "buffer" by arrays:
std::vector<GLfloat> mesh_vertex;
std::vector<GLfloat> mesh_normals;
std::vector<GLfloat> mesh_colors;
std::vector<GLfloat> mesh_textCoords;
std::vector<GLuint> mesh_indices;
/*fill index array*/
for (long i = 0; i < shapes[s].mesh.indices.size(); i++)
{
mesh_indices.push_back(shapes[s].mesh.indices[i].vertex_index);
}
/*-----------------------------------------------------------*/
// Check for smoothing group and compute smoothing normals
std::map<int, vec3> smoothVertexNormals;
if (hasSmoothingGroup(shapes[s]) > 0) {
std::cout << "Compute smoothingNormal for shape [" << s << "]" << std::endl;
computeSmoothingNormals(attrib, shapes[s], smoothVertexNormals);
}
for (size_t f = 0; f < shapes[s].mesh.indices.size() / 3; f++) {
tinyobj::index_t idx0 = shapes[s].mesh.indices[3 * f + 0];
tinyobj::index_t idx1 = shapes[s].mesh.indices[3 * f + 1];
tinyobj::index_t idx2 = shapes[s].mesh.indices[3 * f + 2];
int current_material_id = shapes[s].mesh.material_ids[f];
if ((current_material_id < 0) ||
(current_material_id >= static_cast<int>(materials.size()))) {
// Invaid material ID. Use default material.
current_material_id =
materials.size() -
1; // Default material is added to the last item in `materials`.
}
// if (current_material_id >= materials.size()) {
// std::cerr << "Invalid material index: " << current_material_id <<
// std::endl;
//}
//
float diffuse[3];
for (size_t i = 0; i < 3; i++) {
diffuse[i] = materials[current_material_id].diffuse[i];
}
float tc[3][2];
if (attrib.texcoords.size() > 0) {
if ((idx0.texcoord_index < 0) || (idx1.texcoord_index < 0) ||
(idx2.texcoord_index < 0)) {
// face does not contain valid uv index.
tc[0][0] = 0.0f;
tc[0][1] = 0.0f;
tc[1][0] = 0.0f;
tc[1][1] = 0.0f;
tc[2][0] = 0.0f;
tc[2][1] = 0.0f;
} else {
assert(attrib.texcoords.size() >
size_t(2 * idx0.texcoord_index + 1));
assert(attrib.texcoords.size() >
size_t(2 * idx1.texcoord_index + 1));
assert(attrib.texcoords.size() >
size_t(2 * idx2.texcoord_index + 1));
// Flip Y coord.
tc[0][0] = attrib.texcoords[2 * idx0.texcoord_index];
tc[0][1] = 1.0f - attrib.texcoords[2 * idx0.texcoord_index + 1];
tc[1][0] = attrib.texcoords[2 * idx1.texcoord_index];
tc[1][1] = 1.0f - attrib.texcoords[2 * idx1.texcoord_index + 1];
tc[2][0] = attrib.texcoords[2 * idx2.texcoord_index];
tc[2][1] = 1.0f - attrib.texcoords[2 * idx2.texcoord_index + 1];
}
} else {
tc[0][0] = 0.0f;
tc[0][1] = 0.0f;
tc[1][0] = 0.0f;
tc[1][1] = 0.0f;
tc[2][0] = 0.0f;
tc[2][1] = 0.0f;
}
float v[3][3];
for (int k = 0; k < 3; k++) {
int f0 = idx0.vertex_index;
int f1 = idx1.vertex_index;
int f2 = idx2.vertex_index;
assert(f0 >= 0);
assert(f1 >= 0);
assert(f2 >= 0);
v[0][k] = attrib.vertices[3 * f0 + k];
v[1][k] = attrib.vertices[3 * f1 + k];
v[2][k] = attrib.vertices[3 * f2 + k];
bmin[k] = std::min(v[0][k], bmin[k]);
bmin[k] = std::min(v[1][k], bmin[k]);
bmin[k] = std::min(v[2][k], bmin[k]);
bmax[k] = std::max(v[0][k], bmax[k]);
bmax[k] = std::max(v[1][k], bmax[k]);
bmax[k] = std::max(v[2][k], bmax[k]);
}
float n[3][3];
{
bool invalid_normal_index = false;
if (attrib.normals.size() > 0) {
int nf0 = idx0.normal_index;
int nf1 = idx1.normal_index;
int nf2 = idx2.normal_index;
if ((nf0 < 0) || (nf1 < 0) || (nf2 < 0)) {
// normal index is missing from this face.
invalid_normal_index = true;
} else {
for (int k = 0; k < 3; k++) {
assert(size_t(3 * nf0 + k) < attrib.normals.size());
assert(size_t(3 * nf1 + k) < attrib.normals.size());
assert(size_t(3 * nf2 + k) < attrib.normals.size());
n[0][k] = attrib.normals[3 * nf0 + k];
n[1][k] = attrib.normals[3 * nf1 + k];
n[2][k] = attrib.normals[3 * nf2 + k];
}
}
} else {
invalid_normal_index = true;
}
if (invalid_normal_index && !smoothVertexNormals.empty()) {
// Use smoothing normals
int f0 = idx0.vertex_index;
int f1 = idx1.vertex_index;
int f2 = idx2.vertex_index;
if (f0 >= 0 && f1 >= 0 && f2 >= 0) {
n[0][0] = smoothVertexNormals[f0].v[0];
n[0][1] = smoothVertexNormals[f0].v[1];
n[0][2] = smoothVertexNormals[f0].v[2];
n[1][0] = smoothVertexNormals[f1].v[0];
n[1][1] = smoothVertexNormals[f1].v[1];
n[1][2] = smoothVertexNormals[f1].v[2];
n[2][0] = smoothVertexNormals[f2].v[0];
n[2][1] = smoothVertexNormals[f2].v[1];
n[2][2] = smoothVertexNormals[f2].v[2];
invalid_normal_index = false;
}
}
if (invalid_normal_index) {
// compute geometric normal
CalcNormal(n[0], v[0], v[1], v[2]);
n[1][0] = n[0][0];
n[1][1] = n[0][1];
n[1][2] = n[0][2];
n[2][0] = n[0][0];
n[2][1] = n[0][1];
n[2][2] = n[0][2];
}
}
for (int k = 0; k < 3; k++) {
/*-----------------------------------------------------------*/
// I leave old calls to "buffer" in comment for understanding
//buffer.push_back(v[k][0]);
//buffer.push_back(v[k][1]);
//buffer.push_back(v[k][2]);
mesh_vertex.push_back(v[k][0]);
mesh_vertex.push_back(v[k][1]);
mesh_vertex.push_back(v[k][2]);
//buffer.push_back(n[k][0]);
//buffer.push_back(n[k][1]);
//buffer.push_back(n[k][2]);
mesh_normals.push_back(n[k][0]);
mesh_normals.push_back(n[k][1]);
mesh_normals.push_back(n[k][2]);
// Combine normal and diffuse to get color.
float normal_factor = 0.2;
float diffuse_factor = 1 - normal_factor;
float c[3] = {n[k][0] * normal_factor + diffuse[0] * diffuse_factor,
n[k][1] * normal_factor + diffuse[1] * diffuse_factor,
n[k][2] * normal_factor + diffuse[2] * diffuse_factor};
float len2 = c[0] * c[0] + c[1] * c[1] + c[2] * c[2];
if (len2 > 0.0f) {
float len = sqrtf(len2);
c[0] /= len;
c[1] /= len;
c[2] /= len;
}
//buffer.push_back(c[0] * 0.5 + 0.5);
//buffer.push_back(c[1] * 0.5 + 0.5);
//buffer.push_back(c[2] * 0.5 + 0.5);
mesh_colors.push_back(c[0] * 0.5 + 0.5);
mesh_colors.push_back(c[1] * 0.5 + 0.5);
mesh_colors.push_back(c[2] * 0.5 + 0.5);
//buffer.push_back(tc[k][0]);
//buffer.push_back(tc[k][1]);
mesh_textCoords.push_back(tc[k][0]);
mesh_textCoords.push_back(tc[k][1]);
/*-----------------------------------------------------------*/
}
}
o.vb_id = 0;
o.numTriangles = 0;
// OpenGL viewer does not support texturing with per-face material.
if (shapes[s].mesh.material_ids.size() > 0 &&
shapes[s].mesh.material_ids.size() > s) {
o.material_id = shapes[s].mesh.material_ids[0]; // use the material ID
// of the first face.
} else {
o.material_id = materials.size() - 1; // = ID for default material.
}
printf("shape[%d] material_id %d\n", int(s), int(o.material_id));
/*-----------------------------------------------------------*/
/*if (buffer.size() > 0) {
glGenBuffers(1, &o.vb_id);
glBindBuffer(GL_ARRAY_BUFFER, o.vb_id);
glBufferData(GL_ARRAY_BUFFER, buffer.size() * sizeof(float),
&buffer.at(0), GL_STATIC_DRAW);
o.numTriangles = buffer.size() / (3 + 3 + 3 + 2) /
3; // 3:vtx, 3:normal, 3:col, 2:texcoord
printf("shape[%d] # of triangles = %d\n", static_cast<int>(s),
o.numTriangles);
}
drawObjects->push_back(o);*/
// Replace by :
GLuint positionVBO = 0;
GLuint texcoordVBO = 0;
GLuint normalVBO = 0;
GLuint indicesEBO = 0;
// Upload per-vertex positions
if (!mesh_vertex.empty())
{
glGenBuffers(1, &positionVBO);
glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
glBufferData(GL_ARRAY_BUFFER, mesh_vertex.size() * sizeof(GLfloat), &mesh_vertex[0], GL_STATIC_DRAW); // GL_DYNAMIC_DRAW ?
glBindBuffer(GL_ARRAY_BUFFER, 0);
positionVBO_array.push_back(positionVBO);
}
// Upload per-vertex texture coordinates
if (!mesh_textCoords.empty())
{
glGenBuffers(1, &texcoordVBO);
glBindBuffer(GL_ARRAY_BUFFER, texcoordVBO);
glBufferData(GL_ARRAY_BUFFER,
mesh_textCoords.size() * sizeof(float),
&mesh_textCoords[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
// Upload per-vertex normals
if (!mesh_normals.empty())
{
glGenBuffers(1, &normalVBO);
glBindBuffer(GL_ARRAY_BUFFER, normalVBO);
glBufferData(GL_ARRAY_BUFFER, mesh_normals.size() * sizeof(GLfloat), &mesh_normals[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
normalVBO_array.push_back(normalVBO);
}
// Upload the indices that form triangles
if (!shapes[0].mesh.indices.empty())
{
glGenBuffers(1, &indicesEBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indicesEBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER,
shapes[s].mesh.indices.size() * sizeof(unsigned int),
shapes[s].mesh.indices.data(), GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
indicesEBO_array.push_back(indicesEBO);
indicesEBOSize_array.push_back(shapes[s].mesh.indices.size());
}
// Hook up vertex/index buffers to a "vertex array object" (VAO)
// VAOs are the closest thing OpenGL has to a "mesh" object.
// VAOs feed data from buffers to the inputs of a vertex shader.
GLuint meshVAO;
vglGenVertexArrays(1, &meshVAO);
meshVAO_array.push_back(meshVAO);// I keep the ids in order to loop inside meshVAO_array in the draw function
// Attach position buffer as attribute 0
if (positionVBO != 0)
{
glBindVertexArray(meshVAO);
// Note: glVertexAttribPointer sets the current
// GL_ARRAY_BUFFER_BINDING as the source of data
// for this attribute.
// That's why we bind a GL_ARRAY_BUFFER before
// calling glVertexAttribPointer then
// unbind right after (to clean things up).
glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
sizeof(float) * 3, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
// Enable the attribute (they are disabled by default
// -- this is very easy to forget!!)
glEnableVertexAttribArray(0);
glBindVertexArray(0);
}
// Attach texcoord buffer as attribute 1
if (texcoordVBO != 0)
{
glBindVertexArray(meshVAO);
glBindBuffer(GL_ARRAY_BUFFER, texcoordVBO);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE,
sizeof(float) * 2, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glEnableVertexAttribArray(1);
glBindVertexArray(0);
}
// Attach normal buffer as attribute 2
if (normalVBO != 0)
{
glBindVertexArray(meshVAO);
glBindBuffer(GL_ARRAY_BUFFER, normalVBO);
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE,
sizeof(float) * 3, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glEnableVertexAttribArray(2);
glBindVertexArray(0);
}
if (indicesEBO != 0)
{
glBindVertexArray(meshVAO);
// Note: Calling glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
// when a VAO is bound attaches the index buffer to the VAO.
// From an API design perspective, this is subtle.
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indicesEBO);
glBindVertexArray(0);
}
/*-----------------------------------------------------------*/
}
}
printf("bmin = %f, %f, %f\n", bmin[0], bmin[1], bmin[2]);
printf("bmax = %f, %f, %f\n", bmax[0], bmax[1], bmax[2]);
return true;
}
（抱歉这个长代码块）
这里是main函数的while循环，与tinyobjloader的唯一区别在于两行之间：
unsigned int program = shaders::CreateShader("data/simple.vert", "data/simple.frag"); // just some really simples shaders
while (glfwWindowShouldClose(window) == GL_FALSE) {
glfwPollEvents();
glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glEnable(GL_TEXTURE_2D);
// camera & rotate
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
GLfloat mat[4][4];
gluLookAt(eye[0], eye[1], eye[2], lookat[0], lookat[1], lookat[2], up[0],
up[1], up[2]);
build_rotmatrix(mat, curr_quat);
glMultMatrixf(&mat[0][0]);
// Fit to -1, 1
glScalef(1.0f / maxExtent, 1.0f / maxExtent, 1.0f / maxExtent);
// Centerize object.
glTranslatef(-0.5 * (bmax[0] + bmin[0]), -0.5 * (bmax[1] + bmin[1]),
-0.5 * (bmax[2] + bmin[2]));
/*-----------------------------------------------------------*/
//Draw(gDrawObjects, materials, textures);
// Can now bind the vertex array object to
// the graphics pipeline, to render with it.
glUseProgram(program);
for (int s = 0; s < meshVAO_array.size(); s++)
{
glBindVertexArray(meshVAO_array[s]);
glDrawElements(GL_TRIANGLES, indicesEBOSize_array[s], GL_UNSIGNED_INT, 0);//mesh.IndexCount
glBindVertexArray(0);
}
glUseProgram(0);
// when done, unbind it from the graphics pipeline:
glBindVertexArray(0);
/*-----------------------------------------------------------*/
glfwSwapBuffers(window);
}
我做错了什么？
在嵌套循环中，shapes[].mesh.indices 的所有索引都用于查找存储在 attrib.vertices、attrib.normals 和 attrib.texcoords 中的属性。
此属性已准备好并线性化。它们以线性数组 mesh_vertex、mesh_normals、mesh_colors 和 mesh_textCoords.
的索引顺序存储
但是索引直接从shapes[].mesh.indices复制到mesh_indices
for (long i = 0; i < shapes[s].mesh.indices.size(); i++)
{
mesh_indices.push_back(shapes[s].mesh.indices[i].vertex_index);
}
mesh_indices 中的索引仍然引用存储在 attrib.vertices 中的顶点坐标，但对新容器中的属性没有任何意义。
不再需要原始索引。新属性的索引将不断递增：[0, 1, 2, 3, 4, 5 ...]
按现有顺序绘制通用顶点属性数据数组就足够了：
// you have to know the number of attributes
// something like mesh_vertex.size() / 3;
GLsizei no_of_attributes = .... ;
glBindVertexArray(meshVAO_array[s]);
glDrawArrays(GL_TRIANGLES, 0, no_of_attributes);
glBindVertexArray(0);
为了将现代 openGl 与 tinyobjloader 一起使用，我正在尝试更改 viewer exemple。 我只是更改了 LoadObjAndConvert 函数，添加我在 tutorial 中看到的顶点数组对象，并且不再使用包含所有数据（位置、索引、颜色、uv）的缓冲区对象，因为看起来我们不能再与现代 openGL 一起使用。
结果看起来我的顶点索引不好，模型只渲染了一部分，如果模型只有一个网格（斯坦福兔子），它甚至不会显示。
代码太长，但是和tinyobjloader viewer example一样，所以我只post个不同的函数
这里是修改的LoadObjAndConvert函数（修改的部分在行之间有帮助）：
static bool LoadObjAndConvert(float bmin[3], float bmax[3],
std::vector<DrawObject>* drawObjects,
std::vector<tinyobj::material_t>& materials,
std::map<std::string, GLuint>& textures,
const char* filename) {
tinyobj::attrib_t attrib;
std::vector<tinyobj::shape_t> shapes;
timerutil tm;
tm.start();
std::string base_dir = GetBaseDir(filename);
if (base_dir.empty()) {
base_dir = ".";
}
#ifdef _WIN32
base_dir += "\";
#else
base_dir += "/";
#endif
std::string err;
bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, filename,
base_dir.c_str());
if (!err.empty()) {
std::cerr << err << std::endl;
}
tm.end();
if (!ret) {
std::cerr << "Failed to load " << filename << std::endl;
return false;
}
printf("Parsing time: %d [ms]\n", (int)tm.msec());
printf("# of vertices = %d\n", (int)(attrib.vertices.size()) / 3);
printf("# of normals = %d\n", (int)(attrib.normals.size()) / 3);
printf("# of texcoords = %d\n", (int)(attrib.texcoords.size()) / 2);
printf("# of materials = %d\n", (int)materials.size());
printf("# of shapes = %d\n", (int)shapes.size());
// Append `default` material
materials.push_back(tinyobj::material_t());
for (size_t i = 0; i < materials.size(); i++) {
printf("material[%d].diffuse_texname = %s\n", int(i),
materials[i].diffuse_texname.c_str());
}
// Load diffuse textures
{
for (size_t m = 0; m < materials.size(); m++) {
tinyobj::material_t* mp = &materials[m];
if (mp->diffuse_texname.length() > 0) {
// Only load the texture if it is not already loaded
if (textures.find(mp->diffuse_texname) == textures.end()) {
GLuint texture_id;
int w, h;
int comp;
std::string texture_filename = mp->diffuse_texname;
if (!FileExists(texture_filename)) {
// Append base dir.
texture_filename = base_dir + mp->diffuse_texname;
if (!FileExists(texture_filename)) {
std::cerr << "Unable to find file: " << mp->diffuse_texname
<< std::endl;
exit(1);
}
}
unsigned char* image =
stbi_load(texture_filename.c_str(), &w, &h, &comp, STBI_default);
if (!image) {
std::cerr << "Unable to load texture: " << texture_filename
<< std::endl;
exit(1);
}
std::cout << "Loaded texture: " << texture_filename << ", w = " << w
<< ", h = " << h << ", comp = " << comp << std::endl;
glGenTextures(1, &texture_id);
glBindTexture(GL_TEXTURE_2D, texture_id);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
if (comp == 3) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB,
GL_UNSIGNED_BYTE, image);
} else if (comp == 4) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA,
GL_UNSIGNED_BYTE, image);
} else {
assert(0); // TODO
}
glBindTexture(GL_TEXTURE_2D, 0);
stbi_image_free(image);
textures.insert(std::make_pair(mp->diffuse_texname, texture_id));
}
}
}
}
bmin[0] = bmin[1] = bmin[2] = std::numeric_limits<float>::max();
bmax[0] = bmax[1] = bmax[2] = -std::numeric_limits<float>::max();
{
for (size_t s = 0; s < shapes.size(); s++) {
/*-----------------------------------------------------------*/
DrawObject o;// I keep this object for later purpose, texture, etc
//std::vector<float> buffer; // pos(3float), normal(3float), color(3float)
//I replace "buffer" by arrays:
std::vector<GLfloat> mesh_vertex;
std::vector<GLfloat> mesh_normals;
std::vector<GLfloat> mesh_colors;
std::vector<GLfloat> mesh_textCoords;
std::vector<GLuint> mesh_indices;
/*fill index array*/
for (long i = 0; i < shapes[s].mesh.indices.size(); i++)
{
mesh_indices.push_back(shapes[s].mesh.indices[i].vertex_index);
}
/*-----------------------------------------------------------*/
// Check for smoothing group and compute smoothing normals
std::map<int, vec3> smoothVertexNormals;
if (hasSmoothingGroup(shapes[s]) > 0) {
std::cout << "Compute smoothingNormal for shape [" << s << "]" << std::endl;
computeSmoothingNormals(attrib, shapes[s], smoothVertexNormals);
}
for (size_t f = 0; f < shapes[s].mesh.indices.size() / 3; f++) {
tinyobj::index_t idx0 = shapes[s].mesh.indices[3 * f + 0];
tinyobj::index_t idx1 = shapes[s].mesh.indices[3 * f + 1];
tinyobj::index_t idx2 = shapes[s].mesh.indices[3 * f + 2];
int current_material_id = shapes[s].mesh.material_ids[f];
if ((current_material_id < 0) ||
(current_material_id >= static_cast<int>(materials.size()))) {
// Invaid material ID. Use default material.
current_material_id =
materials.size() -
1; // Default material is added to the last item in `materials`.
}
// if (current_material_id >= materials.size()) {
// std::cerr << "Invalid material index: " << current_material_id <<
// std::endl;
//}
//
float diffuse[3];
for (size_t i = 0; i < 3; i++) {
diffuse[i] = materials[current_material_id].diffuse[i];
}
float tc[3][2];
if (attrib.texcoords.size() > 0) {
if ((idx0.texcoord_index < 0) || (idx1.texcoord_index < 0) ||
(idx2.texcoord_index < 0)) {
// face does not contain valid uv index.
tc[0][0] = 0.0f;
tc[0][1] = 0.0f;
tc[1][0] = 0.0f;
tc[1][1] = 0.0f;
tc[2][0] = 0.0f;
tc[2][1] = 0.0f;
} else {
assert(attrib.texcoords.size() >
size_t(2 * idx0.texcoord_index + 1));
assert(attrib.texcoords.size() >
size_t(2 * idx1.texcoord_index + 1));
assert(attrib.texcoords.size() >
size_t(2 * idx2.texcoord_index + 1));
// Flip Y coord.
tc[0][0] = attrib.texcoords[2 * idx0.texcoord_index];
tc[0][1] = 1.0f - attrib.texcoords[2 * idx0.texcoord_index + 1];
tc[1][0] = attrib.texcoords[2 * idx1.texcoord_index];
tc[1][1] = 1.0f - attrib.texcoords[2 * idx1.texcoord_index + 1];
tc[2][0] = attrib.texcoords[2 * idx2.texcoord_index];
tc[2][1] = 1.0f - attrib.texcoords[2 * idx2.texcoord_index + 1];
}
} else {
tc[0][0] = 0.0f;
tc[0][1] = 0.0f;
tc[1][0] = 0.0f;
tc[1][1] = 0.0f;
tc[2][0] = 0.0f;
tc[2][1] = 0.0f;
}
float v[3][3];
for (int k = 0; k < 3; k++) {
int f0 = idx0.vertex_index;
int f1 = idx1.vertex_index;
int f2 = idx2.vertex_index;
assert(f0 >= 0);
assert(f1 >= 0);
assert(f2 >= 0);
v[0][k] = attrib.vertices[3 * f0 + k];
v[1][k] = attrib.vertices[3 * f1 + k];
v[2][k] = attrib.vertices[3 * f2 + k];
bmin[k] = std::min(v[0][k], bmin[k]);
bmin[k] = std::min(v[1][k], bmin[k]);
bmin[k] = std::min(v[2][k], bmin[k]);
bmax[k] = std::max(v[0][k], bmax[k]);
bmax[k] = std::max(v[1][k], bmax[k]);
bmax[k] = std::max(v[2][k], bmax[k]);
}
float n[3][3];
{
bool invalid_normal_index = false;
if (attrib.normals.size() > 0) {
int nf0 = idx0.normal_index;
int nf1 = idx1.normal_index;
int nf2 = idx2.normal_index;
if ((nf0 < 0) || (nf1 < 0) || (nf2 < 0)) {
// normal index is missing from this face.
invalid_normal_index = true;
} else {
for (int k = 0; k < 3; k++) {
assert(size_t(3 * nf0 + k) < attrib.normals.size());
assert(size_t(3 * nf1 + k) < attrib.normals.size());
assert(size_t(3 * nf2 + k) < attrib.normals.size());
n[0][k] = attrib.normals[3 * nf0 + k];
n[1][k] = attrib.normals[3 * nf1 + k];
n[2][k] = attrib.normals[3 * nf2 + k];
}
}
} else {
invalid_normal_index = true;
}
if (invalid_normal_index && !smoothVertexNormals.empty()) {
// Use smoothing normals
int f0 = idx0.vertex_index;
int f1 = idx1.vertex_index;
int f2 = idx2.vertex_index;
if (f0 >= 0 && f1 >= 0 && f2 >= 0) {
n[0][0] = smoothVertexNormals[f0].v[0];
n[0][1] = smoothVertexNormals[f0].v[1];
n[0][2] = smoothVertexNormals[f0].v[2];
n[1][0] = smoothVertexNormals[f1].v[0];
n[1][1] = smoothVertexNormals[f1].v[1];
n[1][2] = smoothVertexNormals[f1].v[2];
n[2][0] = smoothVertexNormals[f2].v[0];
n[2][1] = smoothVertexNormals[f2].v[1];
n[2][2] = smoothVertexNormals[f2].v[2];
invalid_normal_index = false;
}
}
if (invalid_normal_index) {
// compute geometric normal
CalcNormal(n[0], v[0], v[1], v[2]);
n[1][0] = n[0][0];
n[1][1] = n[0][1];
n[1][2] = n[0][2];
n[2][0] = n[0][0];
n[2][1] = n[0][1];
n[2][2] = n[0][2];
}
}
for (int k = 0; k < 3; k++) {
/*-----------------------------------------------------------*/
// I leave old calls to "buffer" in comment for understanding
//buffer.push_back(v[k][0]);
//buffer.push_back(v[k][1]);
//buffer.push_back(v[k][2]);
mesh_vertex.push_back(v[k][0]);
mesh_vertex.push_back(v[k][1]);
mesh_vertex.push_back(v[k][2]);
//buffer.push_back(n[k][0]);
//buffer.push_back(n[k][1]);
//buffer.push_back(n[k][2]);
mesh_normals.push_back(n[k][0]);
mesh_normals.push_back(n[k][1]);
mesh_normals.push_back(n[k][2]);
// Combine normal and diffuse to get color.
float normal_factor = 0.2;
float diffuse_factor = 1 - normal_factor;
float c[3] = {n[k][0] * normal_factor + diffuse[0] * diffuse_factor,
n[k][1] * normal_factor + diffuse[1] * diffuse_factor,
n[k][2] * normal_factor + diffuse[2] * diffuse_factor};
float len2 = c[0] * c[0] + c[1] * c[1] + c[2] * c[2];
if (len2 > 0.0f) {
float len = sqrtf(len2);
c[0] /= len;
c[1] /= len;
c[2] /= len;
}
//buffer.push_back(c[0] * 0.5 + 0.5);
//buffer.push_back(c[1] * 0.5 + 0.5);
//buffer.push_back(c[2] * 0.5 + 0.5);
mesh_colors.push_back(c[0] * 0.5 + 0.5);
mesh_colors.push_back(c[1] * 0.5 + 0.5);
mesh_colors.push_back(c[2] * 0.5 + 0.5);
//buffer.push_back(tc[k][0]);
//buffer.push_back(tc[k][1]);
mesh_textCoords.push_back(tc[k][0]);
mesh_textCoords.push_back(tc[k][1]);
/*-----------------------------------------------------------*/
}
}
o.vb_id = 0;
o.numTriangles = 0;
// OpenGL viewer does not support texturing with per-face material.
if (shapes[s].mesh.material_ids.size() > 0 &&
shapes[s].mesh.material_ids.size() > s) {
o.material_id = shapes[s].mesh.material_ids[0]; // use the material ID
// of the first face.
} else {
o.material_id = materials.size() - 1; // = ID for default material.
}
printf("shape[%d] material_id %d\n", int(s), int(o.material_id));
/*-----------------------------------------------------------*/
/*if (buffer.size() > 0) {
glGenBuffers(1, &o.vb_id);
glBindBuffer(GL_ARRAY_BUFFER, o.vb_id);
glBufferData(GL_ARRAY_BUFFER, buffer.size() * sizeof(float),
&buffer.at(0), GL_STATIC_DRAW);
o.numTriangles = buffer.size() / (3 + 3 + 3 + 2) /
3; // 3:vtx, 3:normal, 3:col, 2:texcoord
printf("shape[%d] # of triangles = %d\n", static_cast<int>(s),
o.numTriangles);
}
drawObjects->push_back(o);*/
// Replace by :
GLuint positionVBO = 0;
GLuint texcoordVBO = 0;
GLuint normalVBO = 0;
GLuint indicesEBO = 0;
// Upload per-vertex positions
if (!mesh_vertex.empty())
{
glGenBuffers(1, &positionVBO);
glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
glBufferData(GL_ARRAY_BUFFER, mesh_vertex.size() * sizeof(GLfloat), &mesh_vertex[0], GL_STATIC_DRAW); // GL_DYNAMIC_DRAW ?
glBindBuffer(GL_ARRAY_BUFFER, 0);
positionVBO_array.push_back(positionVBO);
}
// Upload per-vertex texture coordinates
if (!mesh_textCoords.empty())
{
glGenBuffers(1, &texcoordVBO);
glBindBuffer(GL_ARRAY_BUFFER, texcoordVBO);
glBufferData(GL_ARRAY_BUFFER,
mesh_textCoords.size() * sizeof(float),
&mesh_textCoords[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
// Upload per-vertex normals
if (!mesh_normals.empty())
{
glGenBuffers(1, &normalVBO);
glBindBuffer(GL_ARRAY_BUFFER, normalVBO);
glBufferData(GL_ARRAY_BUFFER, mesh_normals.size() * sizeof(GLfloat), &mesh_normals[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
normalVBO_array.push_back(normalVBO);
}
// Upload the indices that form triangles
if (!shapes[0].mesh.indices.empty())
{
glGenBuffers(1, &indicesEBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indicesEBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER,
shapes[s].mesh.indices.size() * sizeof(unsigned int),
shapes[s].mesh.indices.data(), GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
indicesEBO_array.push_back(indicesEBO);
indicesEBOSize_array.push_back(shapes[s].mesh.indices.size());
}
// Hook up vertex/index buffers to a "vertex array object" (VAO)
// VAOs are the closest thing OpenGL has to a "mesh" object.
// VAOs feed data from buffers to the inputs of a vertex shader.
GLuint meshVAO;
vglGenVertexArrays(1, &meshVAO);
meshVAO_array.push_back(meshVAO);// I keep the ids in order to loop inside meshVAO_array in the draw function
// Attach position buffer as attribute 0
if (positionVBO != 0)
{
glBindVertexArray(meshVAO);
// Note: glVertexAttribPointer sets the current
// GL_ARRAY_BUFFER_BINDING as the source of data
// for this attribute.
// That's why we bind a GL_ARRAY_BUFFER before
// calling glVertexAttribPointer then
// unbind right after (to clean things up).
glBindBuffer(GL_ARRAY_BUFFER, positionVBO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE,
sizeof(float) * 3, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
// Enable the attribute (they are disabled by default
// -- this is very easy to forget!!)
glEnableVertexAttribArray(0);
glBindVertexArray(0);
}
// Attach texcoord buffer as attribute 1
if (texcoordVBO != 0)
{
glBindVertexArray(meshVAO);
glBindBuffer(GL_ARRAY_BUFFER, texcoordVBO);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE,
sizeof(float) * 2, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glEnableVertexAttribArray(1);
glBindVertexArray(0);
}
// Attach normal buffer as attribute 2
if (normalVBO != 0)
{
glBindVertexArray(meshVAO);
glBindBuffer(GL_ARRAY_BUFFER, normalVBO);
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE,
sizeof(float) * 3, 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glEnableVertexAttribArray(2);
glBindVertexArray(0);
}
if (indicesEBO != 0)
{
glBindVertexArray(meshVAO);
// Note: Calling glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
// when a VAO is bound attaches the index buffer to the VAO.
// From an API design perspective, this is subtle.
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indicesEBO);
glBindVertexArray(0);
}
/*-----------------------------------------------------------*/
}
}
printf("bmin = %f, %f, %f\n", bmin[0], bmin[1], bmin[2]);
printf("bmax = %f, %f, %f\n", bmax[0], bmax[1], bmax[2]);
return true;
}
（抱歉这个长代码块）
这里是main函数的while循环，与tinyobjloader的唯一区别在于两行之间：
unsigned int program = shaders::CreateShader("data/simple.vert", "data/simple.frag"); // just some really simples shaders
while (glfwWindowShouldClose(window) == GL_FALSE) {
glfwPollEvents();
glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glEnable(GL_TEXTURE_2D);
// camera & rotate
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
GLfloat mat[4][4];
gluLookAt(eye[0], eye[1], eye[2], lookat[0], lookat[1], lookat[2], up[0],
up[1], up[2]);
build_rotmatrix(mat, curr_quat);
glMultMatrixf(&mat[0][0]);
// Fit to -1, 1
glScalef(1.0f / maxExtent, 1.0f / maxExtent, 1.0f / maxExtent);
// Centerize object.
glTranslatef(-0.5 * (bmax[0] + bmin[0]), -0.5 * (bmax[1] + bmin[1]),
-0.5 * (bmax[2] + bmin[2]));
/*-----------------------------------------------------------*/
//Draw(gDrawObjects, materials, textures);
// Can now bind the vertex array object to
// the graphics pipeline, to render with it.
glUseProgram(program);
for (int s = 0; s < meshVAO_array.size(); s++)
{
glBindVertexArray(meshVAO_array[s]);
glDrawElements(GL_TRIANGLES, indicesEBOSize_array[s], GL_UNSIGNED_INT, 0);//mesh.IndexCount
glBindVertexArray(0);
}
glUseProgram(0);
// when done, unbind it from the graphics pipeline:
glBindVertexArray(0);
/*-----------------------------------------------------------*/
glfwSwapBuffers(window);
}
我做错了什么？
在嵌套循环中，shapes[].mesh.indices 的所有索引都用于查找存储在 attrib.vertices、attrib.normals 和 attrib.texcoords 中的属性。
此属性已准备好并线性化。它们以线性数组 mesh_vertex、mesh_normals、mesh_colors 和 mesh_textCoords.
但是索引直接从shapes[].mesh.indices复制到mesh_indices
for (long i = 0; i < shapes[s].mesh.indices.size(); i++)
{
mesh_indices.push_back(shapes[s].mesh.indices[i].vertex_index);
}
mesh_indices 中的索引仍然引用存储在 attrib.vertices 中的顶点坐标，但对新容器中的属性没有任何意义。
不再需要原始索引。新属性的索引将不断递增：[0, 1, 2, 3, 4, 5 ...]
按现有顺序绘制通用顶点属性数据数组就足够了：
// you have to know the number of attributes
// something like mesh_vertex.size() / 3;
GLsizei no_of_attributes = .... ;
glBindVertexArray(meshVAO_array[s]);
glDrawArrays(GL_TRIANGLES, 0, no_of_attributes);
glBindVertexArray(0);