Imgui: Create custom font without using the BuildAtlas code path

[aiekick]

Hello,

i have font datas, like a texture atlas, and the rect of each glyph, and font infos like xadvance

i there a easy way to create an empty ImFont, and after add glyph infos for each char's ?

i have search in the source code on imgui, but its difficult to understand how it work, i know that ImConfig contain the general infos of the font, but it contain also a ttf buffer, and if i not pass this buffer, there is a assert ..

in my case i not have the ttf infos, but i have all the final infos of each glyphs.

Maybe we can have a ImFontAtlas::AddEmptyFont(const ImFontConfig* font_cfg)
And affter that specify texture atlas to use, and add the glyphs to the font

I dont know how i can achieve this, but maybe you have some ideas i can try ?

i have tried, this for the custom font :

ImFont *font = m_TestFontAtlas.AddFont(&m_TestFontConfig);
if (font)
{
    font->FontSize = 30.0f;
    font->ConfigData = &m_TestFontConfig;
    font->ConfigDataCount = 1;
    m_TestFontAtlas.TexID = (ImTextureID)GenerationThread::Params->textureFont;

    font->ContainerAtlas = &m_TestFontAtlas;

    for (auto it = GenerationThread::Params->Glyphs.begin(); it != GenerationThread::Params->Glyphs.end(); ++it)
    {
        auto c = it->first;
        GlyphStruct *g = &(it->second);
        font->AddGlyph((ImWchar)c,
            g->rect.x, g->rect.y,
            g->rect.x + g->rect.z, g->rect.y + g->rect.w,
            g->rc.x, g->rc.y,
            g->rc.z, g->rc.w,
            g->advx);
    }

    font->BuildLookupTable();
}

after that i push the font, but in my InputTextMultiline, i see weird things :unamused:

when i type chars, they are displayed in wrong order..

Thanks

[ocornut]

You can use ShowStyleEditor() to browse and debug the fonts and individual glyphs, hopefully it can help to understand what's wrong with the code.

[ocornut]

I think your X0/Y0/X1/Y1 position are wrong, they are the offset for each character.

So maybe for a start change

        font->AddGlyph((ImWchar)c,
            g->rect.x, g->rect.y,
            g->rect.x + g->rect.z, g->rect.y + g->rect.w,
            g->rc.x, g->rc.y,
            g->rc.z, g->rc.w,
            g->advx);

to

        font->AddGlyph((ImWchar)c,
            0, 0,
            g->rect.z, g->rect.w,
            g->rc.x, g->rc.y,
            g->rc.z, g->rc.w,
            g->advx);

But your GlyphStruct may have another offset to take account of.

[aiekick]

thanks. yep i not really understood well what corners was :) i though it was pos + size, but no its a rect :)

so i done that finally :

m_TestFontAtlas.TexID = (ImTextureID)FontGenerator::Instance()->
        m_Font_RenderPack->GetTextureId(m_CurrentAttachmentId);

m_TestFont->ContainerAtlas = &m_TestFontAtlas;

int pdx = GenerationThread::Params->glyphPadding.x;

int lh = (GenerationThread::Params->lineHeight) * GenerationThread::Params->scale;
int bh = (GenerationThread::Params->baseHeight) * GenerationThread::Params->scale;

m_TestFont->Ascent = bh;
m_TestFont->Descent = bh - lh;

for (auto it = GenerationThread::Params->Glyphs.begin(); it != GenerationThread::Params->Glyphs.end(); ++it)
{
    auto c = it->first;
    GlyphStruct *glyph = &(it->second);

    int sx = glyph->size.x * GenerationThread::Params->scale;
    int sy = glyph->size.y * GenerationThread::Params->scale;

    int hbx = glyph->horiBearing.x * GenerationThread::Params->scale;
    int hby = glyph->horiBearing.y * GenerationThread::Params->scale;

    int advx = (glyph->advx) * GenerationThread::Params->scale + pdx;

    m_TestFont->AddGlyph((ImWchar)c,
        hbx, bh - hby,
        hbx + sx, bh - hby + sy,
        glyph->rc.x, glyph->rc.y,
        glyph->rc.z, glyph->rc.w,
        advx);
}

and i obtain that ! :satisfied:

[meshula]

That tool looks great :)

[aiekick]

i will be released soon under MIT license but closed source :) you can follow me on twitter for have news :)

[meshula]

Ok, done :)

[ocornut]

Good to hear the problem is solved! I will add a comment to AddGlyph() to clarify the parameters.
Closing this.

[aiekick]

but when i watch the font in the style editor i not have a good font map ..

i thinkc the texture used by " font->RenderChar " is not the good one ?
but i dont know where i can specify the good one

do you know where search the problem ?

[ocornut]

It's not pushing the texture into the draw list stack... you can add that but that will create many draw calls as the imgui lines and shapes cannot be drawn with your texture unless it is also part of a texture atlas (atlas->TexUvWhitePixel UV coordinates need to point to 4 white pixels in the texture for the rest to render).

It would be easier if you used atlas->AddCustomRectFontGlyph() and copied your texture glyph-per-glyph into the main atlas.

[aiekick]

ok in understand.

In more if i decide to use my custom font bitmap, all frames are disapearing, i dont know why all items except font are impacted : it is what you say about the lines ?