c++ - glBufferData and glBufferSubData Offset -

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i'm attempting render suzanne (from blender) in opengl 3.3, buffer data doesn't seem correct. this:

https://gyazo.com/ab82f9acb6854a49fccc527ed96cc4e8

i tried render sphere simple texture:

https://gyazo.com/85c1e87fcc4eab128ca37b1a0cb1deaa

my importer inserts vertex data std::vector single floats:

if(line.substr(0,2) == "v ") { /** vertex position */     std::istringstream s(line.substr(2));     float v[3];     s >> v[0]; s >> v[1]; s >> v[2];      this->vertices.push_back(v[0]);     this->vertices.push_back(v[1]);     this->vertices.push_back(v[2]); }

i setup array buffer follows:

glgenbuffers(1, &this->vbo); glbindbuffer(gl_array_buffer, this->vbo);  glbufferdata(gl_array_buffer,     sizeof(float)*(this->vertices.size()+this->textures.size()+this->normals.size()),     null,     gl_static_draw);

and insert actual data using glbuffersubdata

glbuffersubdata(gl_array_buffer, 0, sizeof(float)*this->vertices.size(), this->vertices.data()); glbuffersubdata(gl_array_buffer, sizeof(float)*this->vertices.size(), sizeof(float)*this->textures.size(), this->textures.data()); glbuffersubdata(gl_array_buffer, sizeof(float)*(this->vertices.size()+this->textures.size()), sizeof(float)*this->normals.size(), this->normals.data());

i insert indices in same way (gl_element_array_buffer of course).

i point information:

glvertexattribpointer(0, 3, gl_float, gl_false, 3*sizeof(float), (glvoid*)0); glvertexattribpointer(0, 3, gl_float, gl_false, 3*sizeof(float), (glvoid*)(sizeof(float)*this->v.size())); glvertexattribpointer(0, 3, gl_float, gl_false, 3*sizeof(float), (glvoid*)(sizeof(float)*this->v.size()+this->vt.size()));

my vertex shader takes in data this:

layout(location = 0) in vec3 position; layout(location = 1) in vec2 texcoord; layout(location = 2) in vec3 normals;

am screwing offsets?

edit: figured out biggest issue! wrote external lua program convert obj files format easier import, ended messing data , duplicating indices on "f #/#/# #/#/# #/#/#" file looked (x->y->x) instead of (x->y->z)

also fixed few other errors responses below!

without seeing shaders can't 100% sure if calls glvertexattribpointer legit. can't tell if want interleaved vertex data in single vbo or not. have packs of vertex positions in first, of texture coordinates, , of normals.

to interleave data first want put of single array (or vector) each vertex repeats pppttnnn pattern. ppp 3 position floats, tt 2 texcoord floats, , nnn 3 normal floats.

it (using bogus types, values, , spacing illustrate pattern):

float[] vertices = {  /* px, py, pz, tx, ty, nx, ny, nz */      1,  1,  1,  0,  0,  1,  1,  1,     // vertex 1      0,  0,  0,  1,  1,  0,  0,  0,     // vertex 2      1,  1,  1,  0,  0,  1,  1,  1,     // vertex 3     ...    };

let's put single vector called vertices, can upload single command:

glbufferdata(gl_array_buffer, sizeof(float) * this->vertices.size(), this->vertices.data(), gl_static_draw);

you put each attribute own vbo. how decide store data on gpu you. if purposely storing data way have it, let me know in comments , i'll update answer.

ok, shader bits.

let's you've got vertex shader looks this:

in vec3 position; in vec2 texcoord; in vec3 normal; out vec2 uv;  void main() {     gl_position = vec4(position, 1);     uv = texcoord; }

and fragment shader looks this:

in vec2 uv; uniform sampler2d image; out vec4 color;  void main() {     color = texture(image, uv); }

then want following glvertexattribpointer calls:

int stride = (3 + 2 + 3) * sizeof(float); glvertexattribpointer(0, 3, gl_float, gl_false, stride, (glvoid*)0); glvertexattribpointer(1, 2, gl_float, gl_false, stride, (glvoid*)3); glvertexattribpointer(2, 3, gl_float, gl_false, stride, (glvoid*)5);

notice how first parameter each call different number. corresponds position, texcoord, normal respectively in vertex shader.

also texture coordinates typically pair of floats (e.g. vec2 texcoord) changed second parameter 2 texcoord call.

finally last parameter, when using interleaved array, needs specify offset per vertex. 0, 3, , 5 position offset, texcoord offset, , normal offset respectively.

hopefully gets want be.

check out docs.gl page on glvertexattribpointer more info.


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