Question

My render method currently looks like this:

void Renderer::render() {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    checkGlError("glClear");

    EntityCamera* camera = (EntityCamera*) resourceManager_->getResource(GHOST_CAMERA);

    mat4 proj;
    Matrix::projection3D(proj, 45.0f,
            (float) nScreenWidth_ / nScreenHeight_, GHOST_NEAR_DISTANCE, GHOST_FAR_DISTANCE);

    mat4 view;
    Matrix::multiply(proj, camera_->getMatrix(), view);
    camera->extractPlanes(view);

    for (vector<Node*>::const_iterator it = renderArray_.begin(); it != renderArray_.end();
            it++) {
        Node* node = *it;
        if (!node->isRenderable()) {
            continue;
        }
        if (node->hasBV() && node->getBV()->isInFrustum(camera, node) == BoundingVolume::OUTSIDE) {
            LOGI("Node %s is outside :O", node->getName().c_str());
            continue;
        }
        EntityModel* entity =
                static_cast<EntityModel*>(resourceManager_->getResource(
                        (*it)->getEntity()));
        if (entity == 0 || entity->getVertices() == 0 || entity->getVertices()->size() == 0) {
            LOGI("Empty entity %s.", node->getName().c_str());
            continue;
        }
        Resource* resource = resourceManager_->getResource(node->getShader());
        Shader* shader = static_cast<Shader*>(resource);
        Resource* resource2 = resourceManager_->getResource(entity->getTexture());
        Image* image = static_cast<Image*>(resource2);
        mat4 res;
        Matrix::multiply(view, node->getMatrix(), res);

        // Select shader program to use.
        glUseProgram(shader->getId());
        checkGlError("glUseProgram");

        int matrix = glGetUniformLocation(shader->getId(), "uWVP");
        int texture = glGetUniformLocation(shader->getId(), "texture_0");
        checkGlError("glGetUniformLocation");
        int textureCoords = glGetAttribLocation(shader->getId(), "attrTexCoords");
        int vertices = glGetAttribLocation(shader->getId(), "attrPos");
        checkGlError("glGetAttribLocation");

        // Specify WVP matrix.
        glUniformMatrix4fv(matrix, 1, false, res);
        checkGlError("glUniformMatrix4fv");

        // Load vertex positions.
        if (!entity->isCompiled()) {
            //LOGI("Entity %s, not compiled.", entity->getName().c_str());
            continue;
        }
        glEnableVertexAttribArray(vertices);
        checkGlError("glEnableVertexAttribArray");
        //glVertexAttribPointer(vertices, 3, GL_FLOAT, GL_FALSE, 0,
        //      &(*entity->getVertices())[0]);
        //LOGI("%s vbo id: %d", node->getName().c_str(), entity->getVBO());
        glBindBuffer(GL_ARRAY_BUFFER, entity->getVBO());
        checkGlError("glBindBuffer");
        glVertexAttribPointer(vertices, 3, GL_FLOAT, GL_FALSE, 0, 0);
        checkGlError("glVertexAttribPointer");
        // Load UV coordinates.
        glEnableVertexAttribArray(textureCoords);
        checkGlError("glEnableVertexAttribArray");
        glVertexAttribPointer(textureCoords, 2, GL_FLOAT, GL_FALSE, 0,
                &(*entity->getTextureCoords())[0]);
        checkGlError("glVertexAttribPointer");

        // Bind the texture.
        glActiveTexture(GL_TEXTURE0);
        checkGlError("glActiveTexture");
        glBindTexture(GL_TEXTURE_2D, image->getId());
        checkGlError("glBindTexture");
        glUniform1i(texture, 0);
        checkGlError("glUniform1i");

        if (entity->hasIndices()) {
            vector<vector<GLushort>*>* indices = entity->getIndices();
            for (unsigned int i = 0; i < indices->size(); i++) {
                if (entity->hasBoundingVolumes()) {
                    BoundingVolume* volume = (*entity->getBoundingVolumes())[i];
                    if (volume->isInFrustum(camera, node) == BoundingVolume::OUTSIDE) {
                        continue;
                    }
                }
                vector<GLushort>* ind = (*indices)[i];
                glDrawElements(GL_TRIANGLES, ind->size(), GL_UNSIGNED_SHORT, &(*ind)[0]);
                checkGlError("glDrawElements");
            }
        }
        else {
            glDrawArrays(GL_TRIANGLES, 0, entity->getVertices()->size() / 3);
            checkGlError("glDrawArrays");
        }
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        checkGlError("glBindBuffer");
    }
}

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I just recently tried to use VBO, before I was sending vertex data directly and everything worked fine, textures were mapped correctly. Now I changed vertex array with VBO and even though it works, no textures are applied, I could only see black object.

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1. What might be wrong with my textures?
2. Why when I change glVertexAttribPointer(vertices, 3, GL_FLOAT, GL_FALSE, 0, 0); line order with glBindBuffer(GL_ARRAY_BUFFER, entity->getVBO()); I get disfigured objects? Is this the right call order that I’m using?

Answer 1

You’re sending your UV coordinates from plain memory, while you seem to send your vertex coordinates from a VBO. This may not be so efficient, you should have both data sets in VBO to profit of the VBO advantages.

That being said, I think your problem is that you don’t unbind your VBO before sending your UV coordinates. Your code should be :

glBindBuffer(GL_ARRAY_BUFFER, 0);
glVertexAttribPointer(textureCoords, 2, GL_FLOAT, GL_FALSE, 0,
            &(*entity->getTextureCoords())[0]);

as I suppose your getTextureCoords() does not return an offset in your VBO.