From 2e4d2f9e4476d6416489e4c63a104a278f96164a Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 25 Oct 2016 19:44:55 +0530
Subject: [PATCH] Implement char rendering

---
 kitty/develop_gl.py | 28 ++++++++++++++++------------
 kitty/fonts.py      |  4 ++++
 kitty/shaders.py    |  4 ++--
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/kitty/develop_gl.py b/kitty/develop_gl.py
index 39744f6e1..48241c9f5 100644
--- a/kitty/develop_gl.py
+++ b/kitty/develop_gl.py
@@ -5,10 +5,9 @@
 import glfw
 import OpenGL.GL as gl
 import sys
-from PIL import Image
-import numpy
 
 from kitty.shaders import ShaderProgram, array
+from kitty.fonts import set_font_family, render_cell, cell_size
 
 vertex_shader = """
 # version 410
@@ -143,30 +142,34 @@ textured_shaders = (
 #version 410
 in vec2 vertex;
 in vec2 texture_position;
-out vec2 texture_position_out;
+out vec2 texture_position_for_fs;
 
 void main() {
     gl_Position = vec4(vertex, 0, 1);
-    texture_position_out = texture_position;
+    texture_position_for_fs = texture_position;
 }
-        ''',
+''',
 
     '''
 #version 410
 uniform sampler2D tex;
-in vec2 texture_position_out;
+in vec2 texture_position_for_fs;
 out vec4 final_color;
+const vec3 background = vec3(0, 1, 0);
+const vec3 foreground = vec3(0, 0, 1);
 
 void main() {
-    final_color = texture(tex, texture_position_out);
+    float alpha = texture(tex, texture_position_for_fs).r;
+    vec3 color = background * (1 - alpha) + foreground * alpha;
+    final_color = vec4(color, 1);
 }
-        ''')
+''')
 
 
 def texture_data():
-    img = Image.open('/home/kovid/work/calibre/resources/images/library.png')
-    img_data = numpy.array(list(img.getdata()), numpy.int8)
-    return img_data, img.size[0], img.size[1]
+    cell = render_cell('K')[0]
+    w, h = cell_size()
+    return cell, w, h
 
 
 def rectangle_texture(window):
@@ -197,9 +200,10 @@ def on_error(code, msg):
 
 
 def main():
+    glfw.glfwSetErrorCallback(on_error)
     if not glfw.glfwInit():
         raise SystemExit('GLFW initialization failed')
-    glfw.glfwSetErrorCallback(on_error)
+    set_font_family('monospace', 144)
     try:
         _main()
     finally:
diff --git a/kitty/fonts.py b/kitty/fonts.py
index 2ed6fa617..c35b798af 100644
--- a/kitty/fonts.py
+++ b/kitty/fonts.py
@@ -262,6 +262,10 @@ def display_bitmap(data, w, h):
     img.show()
 
 
+def cell_size():
+    return cell_width, cell_height
+
+
 def test_rendering(text='Ping👁a', sz=144, family='monospace'):
     set_font_family(family, sz)
     cells = []
diff --git a/kitty/shaders.py b/kitty/shaders.py
index 8d395f99d..e433666e0 100644
--- a/kitty/shaders.py
+++ b/kitty/shaders.py
@@ -87,7 +87,7 @@ class ShaderProgram:
         gl.glUseProgram(0)
         self.is_active = False
 
-    def set_2d_texture(self, var_name, data, width, height, data_type='rgba',
+    def set_2d_texture(self, var_name, data, width, height, data_type='red',
                        min_filter=gl.GL_LINEAR, mag_filter=gl.GL_LINEAR,
                        swrap=gl.GL_CLAMP_TO_EDGE, twrap=gl.GL_CLAMP_TO_EDGE):
         texture_id = self.texture_id = gl.glGenTextures(1)
@@ -101,7 +101,7 @@ class ShaderProgram:
         internal_format, external_format = {
             'rgba': (gl.GL_RGBA8, gl.GL_RGBA),
             'rgb': (gl.GL_RGB8, gl.GL_RGB),
-            'red': (gl.GL_RED, gl.GL_RED),
+            'red': (gl.GL_R8, gl.GL_RED),
         }[data_type]
         gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, internal_format, width, height,
                         0, external_format, gl.GL_UNSIGNED_BYTE, data)