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require 'imlib2'
class OpenGLTextManager
def initialize
@textures = Hash.new
blank_filename = 'res/img/blank.png' # 1x1 png image
@blank = Imlib2::Image::load(blank_filename)
# Probably better to copy the font locally and load it from there
Imlib2::Font::add_path '/usr/share/fonts/truetype/ttf-bitstream-vera'
fontname = 'Vera/10'
@font = Imlib2::Font.new(fontname)
end
def render text, x, y
texture = @textures[text]
texture = create_texture(text) if texture == nil
# Draw a quad with the text texture
# Looks best with Ortho 1:1 projection
GL::Enable(GL::TEXTURE_2D);
GL::LoadIdentity();
GL.BindTexture(GL::TEXTURE_2D, texture.ogl);
GL::Begin(GL::QUADS);
GL::TexCoord(0.0, 0.0); GL::Vertex(x, y)
GL::TexCoord(0.0, 1.0); GL::Vertex(x, texture.height + y)
GL::TexCoord(1.0, 1.0); GL::Vertex(texture.width + x, texture.height + y)
GL::TexCoord(1.0, 0.0); GL::Vertex(texture.width + x, y)
GL::End()
end
def create_texture text
fw, fh = @font.size(text)
# This is a hack
# Image.new doesn't have the right color format (or something),
# so just resize a preloaded png
image = @blank.clone
image.crop_scaled! 0,0,image.width, image.height, fw, fh
image.fill_rect [0,0], [image.w, image.h], Imlib2::Color::RgbaColor.new(0,0,0,255)
image.draw_text @font, text, 0, 0, Imlib2::Color::WHITE
texture = TextTexture.new
texture.ogl = GL::GenTextures(1)[0];
GL.BindTexture(GL::TEXTURE_2D, texture.ogl);
GL.TexParameteri(GL::TEXTURE_2D, GL::TEXTURE_WRAP_S, GL::CLAMP);
GL.TexParameteri(GL::TEXTURE_2D, GL::TEXTURE_WRAP_T, GL::CLAMP);
GL.TexParameteri(GL::TEXTURE_2D, GL::TEXTURE_MAG_FILTER,GL::LINEAR);
GL.TexParameteri(GL::TEXTURE_2D, GL::TEXTURE_MIN_FILTER,GL::LINEAR);
GL.TexImage2D(GL::TEXTURE_2D, 0, GL::RGBA, image.width,
image.height, 0, GL::RGBA, GL::UNSIGNED_BYTE, image.rgba_data);
texture.width = image.width
texture.height = image.height
image.delete!
@textures[text] = texture
return texture
end
def get_texture text
texture = @textures[text]
texture = create_texture(text) if texture == nil
texture
end
end
class TextTexture
attr_accessor :ogl
attr_accessor :width
attr_accessor :height
end
class Imlib2::Image
# Convert data to format compatible with OpenGL
def rgba_data
new_data = Array.new(data.size)
i = 0
for i in (0..data.size/4-1)
new_data[i*4] = data[i*4+2]
new_data[i*4+1] = data[i*4+1]
new_data[i*4+2] = data[i*4+0]
new_data[i*4+3] = data[i*4+3]
end
return new_data.pack('C*')
end
end
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