我正在尝试使用FreeType和OpenGL渲染一些文本:
text = "fghjRT-123VWYUGHJ$@%"
有两个问题:
我的渲染代码:
/* top left position on screen to render text (yellow border) */
Vector<2> pos = params.rect.left_top();
/* adjust to bottom (how to get correct origin position?) */
pos.y() += font->char_size();
for (char ch : params.text)
{
/* contains info after freetype FT_LoadGlyph */
FontChar const* char_info = font->find_char(ch);
RectF char_rect(
pos - char_info->bearing(), /* left, top */
char_info->glyph_rect().size() /* width, height */
);
/* convert screen coordinates to OpenGL coordinates */
RectF dr = calc_coord(m_screen_size, char_rect);
/* pack position of glyph and it's texture from bitmap
* into one sequence of data
*/
Vector<16> spr_coords = pack_spr_info(dr, char_info->rect());
m_sprite_buffer.push_back(spr_coords);
/* move pen by advance */
pos.x() += char_info->advance();
}
我的字形加载代码片段:
FT_GlyphSlot slot = face->glyph;
char_info->bearing() = {
slot->metrics.horiBearingX / 64.0f,
slot->metrics.horiBearingY / 64.0f
};
char_info->glyph_rect() = {
slot->metrics.horiBearingX / 64.0f, /* left */
slot->metrics.horiBearingY / 64.0f, /* top */
slot->metrics.width / 64.0f, /* width */
slot->metrics.height / 64.0f /* height */
};
char_info->advance() = slot->metrics.horiAdvance / 64.0f;
答案 0 :(得分:2)
好,我自己找到答案了。
我的char_rect
职位计算有误。正确方法:
RectF char_rect(
pos.x() + char_info->bearing().x(), /* left */
pos.y() - char_info->bearing().y(), /* top */
char_info->glyph_rect().size() /* width, height */
);
从顶部边框调整查找基线(原点)的方式:
Vector<2> pos = params.rect.left_top();
pos.y() += font->ascend(); /* move pen down on the screen */
位置:
FT_Face face = ...;
font->ascend() = face->ascender / 32;