Method upload_atlas

src/visualization/gl_text_renderer.cpp:66–124

}

void GLTextRenderer::upload_atlas() {
    canvas_.glActiveTexture(GL_TEXTURE0);
    canvas_.glBindTexture(GL_TEXTURE_2D, text_tex);

    text_texture_width = atlas_.texture_width;
    text_texture_height = atlas_.texture_height;

    {
        constexpr auto mipmap_levels = 5;
        auto tex_level_width = static_cast<int>(text_texture_width);
        auto tex_level_height = static_cast<int>(text_texture_height);

        for (int i = 0; i < mipmap_levels; ++i) {
            canvas_.glTexImage2D(GL_TEXTURE_2D,
                                 i,
                                 GL_R8,
                                 tex_level_width,
                                 tex_level_height,
                                 0,
                                 GL_RED,
                                 GL_UNSIGNED_BYTE,
                                 nullptr);

            tex_level_width = (std::max)(1, tex_level_width / 2);
            tex_level_height = (std::max)(1, tex_level_height / 2);
        }
    }

    {
        canvas_.glTexSubImage2D(GL_TEXTURE_2D,
                                0,
                                0,
                                0,
                                static_cast<GLsizei>(text_texture_width),
                                static_cast<GLsizei>(text_texture_height),
                                GL_RED,
                                GL_UNSIGNED_BYTE,
                                atlas_.pixels.data());
    }

    text_texture_offsets = atlas_.offsets;
    text_texture_advances = atlas_.advances;
    text_texture_sizes = atlas_.sizes;
    text_texture_tls = atlas_.tls;

    canvas_.glGenerateMipmap(GL_TEXTURE_2D);
    canvas_.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    canvas_.glTexParameteri(
        GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    const auto& dialect = the_dialect();
    const auto wrap_mode =
        dialect.has_texture_wrap_r ? GL_CLAMP_TO_BORDER : GL_CLAMP_TO_EDGE;
    canvas_.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap_mode);
    canvas_.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrap_mode);
    if (dialect.has_texture_wrap_r) {
        canvas_.glTexParameteri(
            GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_BORDER);
    }