Add a class for easier text rendering

[libs/gl.git] / source / text.cpp

diff --git a/source/text.cpp b/source/text.cpp
new file mode 100644 (file)
index 0000000..e3a8540
--- /dev/null
+++ b/source/text.cpp
@@ -0,0 +1,95 @@
+#include "meshbuilder.h"
+#include "text.h"
+#include "texture2d.h"
+
+using namespace std;
+
+namespace Msp {
+namespace GL {
+
+Text::Text(const Font &f, const Technique *tech):
+       font(f),
+       mesh((TEXCOORD2, VERTEX2)),
+       horz_align(0.0f),
+       vert_offset(0.0f)
+{
+       object.set_mesh(&mesh);
+       if(tech)
+               set_technique(tech);
+}
+
+void Text::set_technique(const Technique *tech)
+{
+       if(tech)
+       {
+               technique = *tech;
+               technique.replace_texture("diffusemap", font.get_texture());
+               object.set_technique(&technique);
+       }
+       else
+               object.set_technique(0);
+}
+
+void Text::set_text(const string &text, StringCodec::Decoder &dec)
+{
+       clear();
+       width = font.get_string_width(text, dec);
+       GL::MeshBuilder bld(mesh);
+       bld.matrix() *= Matrix::translation(Vector3(-horz_align*width, vert_offset, 0.0f));
+       font.build_string(text, dec, bld);
+}
+
+void Text::clear()
+{
+       mesh.clear();
+       width = 0;
+}
+
+void Text::set_alignment(HorizontalAlign ha, VerticalAlign va)
+{
+       float h;
+       switch(ha)
+       {
+       case LEFT: h = 0.0f; break;
+       case CENTER: h = 0.5f; break;
+       case RIGHT: h = 1.0f; break;
+       default: throw invalid_argument("Text::set_alignment");
+       }
+
+       float v;
+       switch(va)
+       {
+       case DESCENT: v = -font.get_descent(); break;
+       case BASELINE: v = 0.0f; break;
+       case MIDLINE: v = font.get_ascent()/2; break;  // XXX Midline should be cap height / 2
+       case ASCENT: v = font.get_ascent(); break;
+       default: throw invalid_argument("Text::set_alignment");
+       }
+
+       set_alignment(h, v);
+}
+
+void Text::set_alignment(float h, float v)
+{
+       float horz_adjust = (horz_align-h)*width;
+       float vert_adjust = -v-vert_offset;
+       horz_align = h;
+       vert_offset = -v;
+
+       unsigned pos_offset = mesh.get_vertices().get_format().offset(VERTEX2);
+       unsigned n_vertices = mesh.get_n_vertices();
+       for(unsigned i=0; i<n_vertices; ++i)
+       {
+               float *pos = mesh.modify_vertex(i)+pos_offset;
+               pos[0] += horz_adjust;
+               pos[1] += vert_adjust;
+       }
+}
+
+void Text::render(Renderer &renderer, const Tag &tag) const
+{
+       object.render(renderer, tag);
+}
+
+} // namespace GL
+} // namespace Msp