Texture renderer (render to texture version)

Author: einarf

demosys/text/base.py

@@ -55,3 +55,10 @@ def __init__(self, meta):
         self.character_width = self._meta['character_width']
         self.atlas_height = self._meta['atlas_height']
         self.atlas_width = self._meta['atlas_width']
+
+    @property
+    def char_aspect_wh(self):
+        return self.character_width / self.character_height
+
+    def char_aspect_hw(self):
+        return self.character_height / self.character_width

demosys/text/renderer2d.py

@@ -1,31 +1,65 @@
+import numpy
+
+import moderngl
+from demosys.opengl import FBO, VAO
 from demosys.resources import shaders
-from .base import BaseText
+
+from .writer2d import TextWriter2D
 
 
-class TextRenderer2D(BaseText):
+class TextRenderer2D(TextWriter2D):
 
-    def __init__(self, area, size=0.1, text=""):
+    def __init__(self, area, text_lines=None, texture_height=64):
         """
         :param area: (x, y) Text area size (number of characters)
         :param size: Text size
         :param text: Initial text
         """
-        super().__init__(text)
-        self.area = area
-        self.size = size
-        self._text = text
+        super().__init__(area, text_lines=text_lines)
+        self._texture_height = texture_height
+        self._texture_width = 0
+
+        self._quad = self._create_vao()
+        # self._quad = geometry.quad_fs()
+        self._quad_shader = shaders.get('demosys/text/view_renderer_texture.glsl', create=True)
+        self._fbo = None
 
-        self.fbo = None
-        self.vao = None
-        self.shader = shaders.get('demosys/text/textwriter.glsl', create=True)
+    def _post_load(self):
+        super()._post_load()
+        self._texture_width = int(
+            round(self._meta.char_aspect_wh * self._texture_height * self.area[0] / self.area[1], 0)
+        )
+
+        self.aspect_ratio = self._texture_width / self._texture_height
+        self._fbo = FBO.create((self._texture_width, self._texture_height))
 
     @property
-    def text(self):
-        return self._text
+    def texture(self):
+        return self._fbo.color_buffers[0]
+
+    def render(self):
+        self._fbo.clear()
+        with self._fbo:
+            super().draw((0.0, 0.0), size=2.0 / self.area[1])
+
+    def draw(self, pos, size=1.0):
+        self._fbo.color_buffers[0].use(location=0)
+        self._quad_shader.uniform("texture0", 0)
+        self._quad_shader.uniform("yscale", self._texture_height / self._texture_width)
+        self._quad_shader.uniform("pos", pos)
+        self._quad_shader.uniform("size", size)
+        self._quad.draw(self._quad_shader)
 
-    @text.setter
-    def text(self, value):
-        self._text = value
+    def _create_vao(self):
+        data = numpy.array([
+            0.0, -2.0, 0.0, 0.0, 0.0,
+            0.0, 0.0, 0.0, 0.0, 1.0,
+            2.0, 0.0, 0.0, 1.0, 1.0,
+            0.0, -2.0, 0.0, 0.0, 0.0,
+            2.0, 0.0, 0.0, 1.0, 1.0,
+            2.0, -2.0, 0.0, 1.0, 0.0,
+        ], dtype=numpy.float32)
 
-    def draw(self):
-        pass
+        vao = VAO("textrenderer", mode=moderngl.TRIANGLES)
+        vao.buffer(data, '3f 2f', ['in_position', 'in_uv'])
+        return vao

demosys/text/resources/shaders/demosys/text/view_renderer_texture.glsl

@@ -0,0 +1,34 @@
+#version 330
+
+#if defined VERTEX_SHADER
+
+in vec3 in_position;
+in vec2 in_uv;
+
+uniform vec2 pos;
+uniform float size;
+uniform float yscale;
+
+out vec2 uv;
+// 
+void main() {
+    vec3 p = vec3(
+        (in_position.x * size) - 1.0 + pos[0],
+        (in_position.y * size) * yscale * 2.0 + 1.0 + pos[1],
+        0.0
+    );
+    gl_Position = vec4(p, 1.0);
+    uv = in_uv;
+}
+
+#elif defined FRAGMENT_SHADER
+
+out vec4 fragColor;
+uniform sampler2D texture0;
+in vec2 uv;
+
+void main() {
+    fragColor = texture(texture0, uv);
+}
+
+#endif

examples/README.md

@@ -58,3 +58,16 @@ python manage.py runeffect examples.textwriter
 ```
 
 ![screenshot](https://raw.githubusercontent.com/Contraz/demosys-py/master/examples/images/textwriter.png)
+
+Text Renderer
+-------------
+
+Example loading a text file displaying it on the screen. The text is rendered to a texture at initialization.
+We simply display the texture each frame. We are limiting the texture height to 8k in this example.
+
+```bash
+python manage.py runeffect examples.textrenderer
+```
+
+![screenshot](https://raw.githubusercontent.com/Contraz/demosys-py/master/examples/images/textrenderer.png)
+

examples/images/textrenderer.png

@@ -0,0 +1,30 @@
+import math
+import os
+
+from demosys.effects import effect
+from demosys.text import TextRenderer2D
+
+
+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.renderer = TextRenderer2D(
+            (105, len(lines)),
+            text_lines=lines,
+            texture_height=8192,
+        )
+
+    def post_load(self):
+        self.renderer.render()
+
+    @effect.bind_target
+    def draw(self, time, frametime, target):
+        self.renderer.draw(
+            (0.05, math.fmod(time, 75.0) / 5.0),
+            size=0.75,
+        )