How to provide 14 float values per vertex to the shader? - c++

Question

I have downloaded a model, and have exported it as .fbx. The model contains several animations (6 to be precise), and I want to have one of them displayed. Following Anton Gerdelan's book on openGL I wrote an importer, which uses assimp to parse the model, buffers the relevant vertex data and retrieves the offset matrices needed for the animation.
Not having much experience with skeletal animation, I think I've been able to make the necessary changes to anton's importer, so that it can work on the more complex model that I need. However, the importer assumes that each vertex is only influenced by 1 bone, which unfortunately is not the case.
After some tinkering, I figured out that each vertex of the model can be influenced by at most 14 bones at a time. Since I am not sure how I could pass 14 values to the shader containing boneId and the relevant weight I tried changing the code to accommodate up to 4 bones at a time. This is the code that parses the bone id & weights and buffers them:
*bone_count = (int)mesh->mNumBones;
char bone_names[256][64];
struct vertexdata {
int IDs[4];
float Weights[4];
int ptr;
};
vector<vertexdata> vdata;
vdata.resize(*point_count);
for (int i = 0; i < *point_count; i++) {
vdata[i].ptr = 0;
}
for (int b_i = 0; b_i < *bone_count; b_i++) {
const aiBone* bone = mesh->mBones[b_i];
strcpy(bone_names[b_i], bone->mName.data);
printf("bone_names[%i]=%s\n", b_i, bone_names[b_i]);
bone_offset_mats[b_i] = convert_assimp_matrix(bone->mOffsetMatrix);
//getting weights for each bone
int num_weights = (int)bone->mNumWeights;
for (int w_i = 0; w_i < num_weights; w_i++) {
aiVertexWeight weight = bone->mWeights[w_i];
int vid = weight.mVertexId;
float vweight = weight.mWeight;
if (vdata[vid].ptr < 4) {
vdata[vid].IDs[vdata[vid].ptr] = b_i;
vdata[vid].Weights[vdata[vid].ptr] = vweight;
vdata[vid].ptr++;
}
int vertex_id = (int)weight.mVertexId;
}
}
//buffering bone id data
GLuint vbo1;
glGenBuffers(1, &vbo1);
glBindBuffer(GL_ARRAY_BUFFER, vbo1);
glBufferData(GL_ARRAY_BUFFER, sizeof(vdata[0]) * vdata.size(), &vdata[0], GL_STATIC_DRAW);
glEnableVertexAttribArray(3);
glVertexAttribIPointer(3, 4, GL_INT, sizeof(vertexdata), (const GLvoid*)0);
glEnableVertexAttribArray(4);
glVertexAttribPointer(4, 4, GL_FLOAT, GL_FALSE, sizeof(vertexdata), (const GLvoid*)16);
and in the shaders:
vertex shader
#version 330 core
layout (location = 0) in vec3 pos;
layout (location = 1) in vec3 norm;
layout (location = 2) in vec2 UV;
layout (location = 3) in ivec4 boneIDs;
layout (location = 4) in vec4 Weights;
uniform mat4 view, projection, model;
uniform mat4 bone_matrices[40];
out vec2 tCoords;
void main()
{
mat4 boneTransform = bone_matrices[boneIDs[0]] * Weights[0];
boneTransform += bone_matrices[boneIDs[1]] * Weights[1];
boneTransform += bone_matrices[boneIDs[2]] * Weights[2];
boneTransform += bone_matrices[boneIDs[3]] * Weights[3];
tCoords = UV;
gl_Position = projection * view * boneTransform * model * vec4(pos, 1.0);
}
fragment shader
#version 330 core
in vec2 tCoords;
out vec4 fragColour;
uniform sampler2D tex;
void main()
{
fragColour = texture(tex, tCoords);
}
The model is rendered properly, but I am not observing any movement. Again, not knowing much about skeletal animation, I can only assume that it's because I haven't included every bone that influences each vertex, and the corresponding weight. However, when buffering the data the shaders only accept up to vec4 aka 4 values per vertex. How can I pass 14 IDs and 14 weights? Could this be the cause of the animation not working?