Working multi line text writer

Author: einarf

demosys/opengl/texture.py

@@ -307,7 +307,6 @@ def set_image(self, image, flip=True):
             image = image.transpose(Image.FLIP_TOP_BOTTOM)
 
         width, height, depth = image.size[0], image.size[1] // self.layers, self.layers
-        print(width, height, depth)
 
         self.mglo = self.ctx.texture_array(
             (width, height, depth),

demosys/text/base.py

@@ -19,9 +19,13 @@ def __init__(self):
     def draw(self, *args, **kwargs):
         raise NotImplementedError()
 
-    def _translate_data(self, data):
-        """Translate character bytes into texture positions"""
-        return [self._meta.characters - 1 - self._ct[c] for c in data]
+    def _translate_string(self, data, length):
+        """Translate string into character texture positions"""
+        for index, char in enumerate(data):
+            if index == length:
+                break
+
+            yield self._meta.characters - 1 - self._ct[char]
 
     def _init(self, meta: 'Meta'):
         self._meta = meta

demosys/text/resources/shaders/demosys/text/textwriter2d.glsl

@@ -6,11 +6,14 @@ in vec3 in_position;
 in uint in_char_id;
 
 uniform vec2 char_size;
+uniform float line_length;
 
 out uint vs_char_id;
 
 void main() {
-	gl_Position = vec4(in_position + vec3(gl_InstanceID * char_size.x, 0.0, 0.0), 1.0);
+    float ypos = int(gl_InstanceID / line_length) * char_size.y;
+    float xpos = mod(gl_InstanceID, line_length) * char_size.x;
+	gl_Position = vec4(in_position + vec3(xpos, -ypos, 0.0), 1.0);
     vs_char_id = in_char_id;
 }
 

demosys/text/resources/shaders/demosys/text/textwriter3d.glsl

@@ -10,17 +10,17 @@
 
 class TextWriter2D(BaseText):
 
-    def __init__(self, area, text="", aspect_ratio=1.0):
+    def __init__(self, area, text_lines=None, aspect_ratio=1.0):
         """
         :param area: (x, y) Text area size (number of characters)
         :param size: Text size
-        :param text: Initial text
+        :param text: Initial text lines
         """
         super().__init__()
         self.area = area
-        self._text = text.encode('latin1')
+        self._text_lines = text_lines
 
-        self.projection_bytes = None
+        self._projection_bytes = None
         self._aspect_ratio = 1.0
         self.aspect_ratio = aspect_ratio
 
@@ -29,29 +29,34 @@ def __init__(self, area, text="", aspect_ratio=1.0):
         self._shader = shaders.get('demosys/text/textwriter2d.glsl', create=True)
         self._config = data.get('demosys/text/meta.json', create=True)
 
+        self._string_buffer = None
+
         data.on_loaded(self._post_load)
 
     def _post_load(self):
         """Parse font metadata after resources are loaded"""
         self._init(Meta(self._config.data))
 
-        self._string_data = self._translate_data(self._text)
-        self._string_buffer = self.ctx.buffer(
-            data=numpy.array(self._string_data, dtype=numpy.uint32).tobytes()
-        )
-        self._pos = self.ctx.buffer(data=bytes([0] * 4 * 3))
+        self._string_buffer = self.ctx.buffer(reserve=self.area[0] * 4 * self.area[1])
+        self._string_buffer.clear(chunk=b'\32')
+        pos = self.ctx.buffer(data=bytes([0] * 4 * 3))
 
         self._vao = VAO("textwriter", mode=moderngl.POINTS)
-        self._vao.buffer(self._pos, '3f', 'in_position')
+        self._vao.buffer(pos, '3f', 'in_position')
         self._vao.buffer(self._string_buffer, '1u', 'in_char_id', per_instance=True)
 
+        self.text_lines = self._text_lines
+
     @property
-    def text(self):
-        return self._text
+    def text_lines(self):
+        return self._text_lines
 
-    @text.setter
-    def text(self, value):
-        self._text = value
+    @text_lines.setter
+    def text_lines(self, value):
+        self._text_lines = value
+
+        for i, line in enumerate(self._text_lines):
+            self.set_text_line(i, line)
 
     @property
     def aspect_ratio(self):
@@ -60,7 +65,7 @@ def aspect_ratio(self):
     @aspect_ratio.setter
     def aspect_ratio(self, value):
         self._aspect_ratio = value
-        self.projection_bytes = matrix44.create_orthogonal_projection_matrix(
+        self._projection_bytes = matrix44.create_orthogonal_projection_matrix(
             -self.aspect_ratio,  # left
             self.aspect_ratio,  # right
             -1.0,  # bottom
@@ -70,19 +75,39 @@ def aspect_ratio(self, value):
             dtype=numpy.float32,
         ).tobytes()
 
-    def draw(self, pos, size=1.0):
+    def set_text_line(self, line, text):
+        if line >= self.area[1]:
+            return
+
+        self._string_buffer.clear(size=self.area[0] * 4, offset=self.area[0] * 4 * line, chunk=b'\32')
+
+        self._string_buffer.write(
+            numpy.fromiter(
+                self._translate_string(text.encode('iso-8859-1'), self.area[0]),
+                dtype=numpy.uint32
+            ).tobytes(),
+            offset=(self.area[0] * 4) * line,
+        )
+
+    def draw(self, pos, lenght=-1, size=1.0):
+        if lenght < 0:
+            lenght = self.area[0] * self.area[1]
+
         csize = (
             self._meta.character_width / self._meta.character_height * size,
             1.0 * size,
         )
+
         cpos = (
             pos[0] - self._aspect_ratio + csize[0] / 2,
             -pos[1] + 1.0 - csize[1] / 2,
         )
 
         self._texture.use(location=0)
-        self._shader.uniform("m_proj", self.projection_bytes)
+        self._shader.uniform("m_proj", self._projection_bytes)
         self._shader.uniform("text_pos", cpos)
         self._shader.uniform("font_texture", 0)
         self._shader.uniform("char_size", csize)
-        self._vao.draw(self._shader, instances=len(self._string_data))
+        self._shader.uniform("line_length", self.area[0])
+
+        self._vao.draw(self._shader, instances=lenght)

demosys/text/writer2d.py

@@ -66,7 +66,6 @@ def run(manager=None):
 
     # Main loop
     frame_time = 60.0 / 1000.0
-    # time_start = glfw.get_time()
     time_start = time.time()
     prev_time = window.timer.get_time()
 

demosys/view/controller.py

@@ -45,3 +45,16 @@ python manage.py runeffect examples.geocubes
 ```
 
 ![screenshot](https://raw.githubusercontent.com/Contraz/demosys-py/master/examples/images/geocubes.png)
+
+Text Writer
+-----------
+
+Example loading a text file displaying it on the screen. The text is drawn using instanced rendering
+were each instance is a character in the file. This may not be the most efficient way for drivers
+emulating instancing. Text renderer (render to texture) is an alternative.
+
+```bash
+python manage.py runeffect examples.textwriter
+```
+
+![screenshot](https://raw.githubusercontent.com/Contraz/demosys-py/master/examples/images/textwriter.png)

examples/README.md

@@ -1,24 +1,24 @@
-import moderngl
+import math
+import os
+
 from demosys.effects import effect
 from demosys.text import TextWriter2D
-# from pyrr import matrix44
 
 
 class TextEffect(effect.Effect):
 
     def __init__(self):
         super().__init__()
+
+        with open(os.path.join(os.path.dirname(__file__), 'sample.txt'), 'r') as fd:
+            lines = fd.readlines()
+
         self.writer = TextWriter2D(
-            (10, 1),
+            (105, len(lines)),
             aspect_ratio=self.window_aspect,
-            text="Hello world! Hello world! Hello world!",
+            text_lines=lines,
         )
 
-    def post_load(self):
-        pass
-
     @effect.bind_target
     def draw(self, time, frametime, target):
-        self.ctx.disable(moderngl.CULL_FACE)
-
-        self.writer.draw((0.02, 0.01), size=0.05)
+        self.writer.draw((0.05, 0.01 - math.fmod(time, 75.0) / 5.0), size=0.05)