Render a scene with openGL

Question

I've to render a scene that include various mesh with openGL. the meshes are defined like this:

struct Mesh {
frame3f         frame;      // frame
vector<vec3f>   pos;        // vertex position
vector<vec3f>   norm;       // vertex normal
vector<vec2f>   texcoord;   // vertex texcture coordinates
vector<vec3i>   triangle;   // triangle
vector<vec4i>   quad;       // quad
Material*       mat;        // material}

the mesh can be made of triangles and quads, I try to render the vertex with this code:

for (auto mesh : scene->meshes)
{
    // bind material kd, ks, n
    glVertexAttrib3f(material_kd_loc, mesh->mat->kd.x, mesh->mat->kd.y, mesh->mat->kd.z);
    glVertexAttrib3f(material_ks_loc, mesh->mat->ks.x, mesh->mat->ks.y, mesh->mat->ks.z);
    glVertexAttrib1f(material_n_loc, mesh->mat->n);

    // bind mesh frame - use frame_to_matrix
    mat4f mesh_mat = frame_to_matrix(mesh->frame);
    glUniformMatrix4fv(mesh_frame_loc, 1, GL_TRUE, &mesh_mat[0][0]);

    // enable vertex attributes arrays
    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);

    //and set up pointers to the mesh data
    glVertexAttribPointer(vertex_pos_loc, mesh->pos.size(), GL_FLOAT, GL_FALSE, 0, mesh->pos.data());
    glVertexAttribPointer(vertex_norm_loc, mesh->norm.size(), GL_FLOAT, GL_TRUE, 0, mesh->norm.data());

    // draw triangles and quads
    if (mesh->triangle.size() != 0){

        glDrawElements(GL_TRIANGLES, mesh->pos.size(), GL_UNSIGNED_INT, mesh->triangle.data());
    }
    if (mesh->quad.size() != 0){
        glDrawElements(GL_QUADS, mesh->pos.size(), GL_UNSIGNED_INT, mesh->quad.data());

    }
    // disable vertex attribute arrays
    glDisableVertexAttribArray(0);
    glDisableVertexAttribArray(1);
}

} this is what i draw (don't care about colors as i don't calculate them yet)

this is what i should see if my code is correct

anyone as an idea of where is the error?

Post your actual (taken from running program, not some input files) positions, triangle and quad arrays contents (they isn't large in given example). — keltar, Oct 25 '13 at 11:07
camera is centered in 0,0,6 thise is the code that creates meshes: — jack_the_beast, Oct 25 '13 at 11:17
new Mesh { frame3f{ {-offset, offset,0}, x3f, y3f, z3f }, { {0,1,0}, {-1,-1,0}, {1,-1,0} }, { z3f, z3f, z3f }, { zero2f, y2f, x2f }, { {0,1,2} }, {}, new Material{one3f,zero3f,100} }, ' — jack_the_beast, Oct 25 '13 at 11:19
new Mesh { frame3f{ { offset, offset,0}, x3f, y3f, z3f }, { {1,1,0}, {-1, 1,0}, {-1,-1,0}, { 1,-1,0} }, { z3f, z3f, z3f, z3f }, { one2f, y2f, zero2f, x2f }, {}, { {0,1,2,3} }, new Material{one3f,zero3f,100} }, — jack_the_beast, Oct 25 '13 at 11:19
new Mesh { identity_frame3f, { {-offset,1-offset,0}, {-1-offset,-1-offset,0}, {1-offset,-1-offset,0} }, { z3f, z3f, z3f }, { zero2f, y2f, x2f }, { {0,1,2} }, {}, new Material{one3f,zero3f,100} }, — jack_the_beast, Oct 25 '13 at 11:20
new Mesh { identity_frame3f, { {1+offset,1-offset,0}, {-1+offset, 1-offset,0}, {-1+offset,-1-offset,0}, { 1+offset,-1-offset,0} }, { z3f, z3f, z3f, z3f }, { one2f, y2f, zero2f, x2f }, {}, { {0,1,2,3} }, new Material{one3f,zero3f,100} }, },' — jack_the_beast, Oct 25 '13 at 11:20

keltar · Answer 1 · 2013-10-25T11:36:44.623

0

glDrawElements(GL_TRIANGLES, mesh->pos.size(), GL_UNSIGNED_INT, mesh->triangle.data());
glDrawElements(GL_QUADS, mesh->quad.size(), GL_UNSIGNED_INT, mesh->quad.data());

Take a look at second argument on both calls. It is incorrect for quads.

glVertexAttribPointer(vertex_pos_loc, mesh->pos.size(), GL_FLOAT, GL_FALSE, 0, mesh->pos.data());

Is incorrect too - second parameter is number of components per vertex, not size of array.

edited Oct 25 '13 at 11:36

answered Oct 25 '13 at 10:51

keltar

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sorry i've paste an old version, now it's edited on the question however i've other (more complex) scenes to render and they are a complete mess with vertex floating around averywhere, so i guess it's only luck that i can render the two triangles correctly – jack_the_beast Oct 25 '13 at 10:56
thanks, now the first scene looks ok. but the other scenes looks weird: looks like some vertex are not drawed.you can see the target images and my images in this [photobucket album](http://s338.photobucket.com/user/jack_the_beast/library/graphic) note that i'm using a shader written by me, it does almost nothing but i can't say if this can cause a problem.... – jack_the_beast Oct 25 '13 at 12:00

score 0 · Accepted Answer · answered Oct 26 '13 at 11:01

look like the opengl function wants the total number of vertecx to be written and not just the number of different vertex. so:

glDrawElements(GL_TRIANGLES, mesh->triangle.size()*3, GL_UNSIGNED_INT, mesh->triangle.data());
glDrawElements(GL_QUADS, mesh->quad.size()*4, GL_UNSIGNED_INT, mesh->quad.data());

Render a scene with openGL

2 Answers2