ged/shaders/font.vert

#version 330 core

#define FONT_WIDTH 128
#define FONT_HEIGHT 64
#define FONT_COLS 18
#define FONT_ROWS 7
#define FONT_CH_W (FONT_WIDTH / FONT_COLS)
#define FONT_CH_H (FONT_HEIGHT / FONT_ROWS)

uniform float scale;
uniform vec2 resolution;
uniform ivec2 cursor;

layout(location = 0) in ivec2 tile;
layout(location = 1) in int c;
layout(location = 2) in vec4 color;

out vec2 uv;
flat out int glyph_c;
out vec4 glyph_fg_color;
out vec4 glyph_bg_color;

vec2 project_point(vec2 point)
{
  return (2.0 * point) / resolution;
}

void main()
{
  uv = vec2(float(gl_VertexID & 1),
	    float((gl_VertexID >> 1) & 1));

  vec2 char_size = vec2(float(FONT_CH_W), float(FONT_CH_H));
  vec2 pos = tile * char_size * scale;
  gl_Position = vec4(project_point(uv * char_size * scale + pos), 0.0, 1.0);

  glyph_c = c;
  glyph_fg_color = color;
  glyph_bg_color = vec4(0);

  if ( tile == cursor ) {
    glyph_fg_color = vec4(0);
    glyph_bg_color = vec4(1);
  }
}