render3d: HUD text, panels and images share a draw - the font stays bound and each vertex says what it reads

A panel and its label alternated the white and font textures, and every switch closed the overlay's
draw range: 77-91 ranges a frame in town. The font atlas is now bound beside the image texture for the
whole flush, and v carries 4 x the vertex's mode (0 image, 1 font, 2 flat colour) on top of its real
coordinate, so only a different image texture or a clip rectangle closes a range. Town: 24 ranges.
OpenGL frames byte-identical at all five viewpoints; MoltenVK with validation adds no message.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/ludic.render3d/overlay.ludic

@@ -17,6 +17,8 @@ var ov_vbo: int = 0
 var ov_buf: pointer = null
 var ov_n: int = 0
 var ov_tex: int = 0
+var ov_mode: int = 2                  # what the next quads read: 0 the image texture, 1 the font, 2 a flat colour
+var ov_voff: int = 0                  # float bits: 4 x ov_mode, added to v (overlay.frag)
 var ov_white: int = 0
 var ov_font: int = 0
 var ov_font_adv: words = null         # float bits, em units, one per glyph in the atlas
@@ -165,6 +167,7 @@ function ov_begin() -> void {
   u_f2(gpu_uniform(ov_prog, "u_screen"), fi(gl_w), fi(gl_h))
   ov_n = 0;  ov_nr = 0;  ov_range_start = 0
   ov_tex = ov_white
+  ov_mode = 2;  ov_voff = fi(8)
   ov_clip_w = 0
   ov_open = true
 }
@@ -198,18 +201,15 @@ function ov_flush() -> void {
   gpu_use_program(ov_prog)
   gpu_mesh_bind(ov_mesh)
   gpu_buffer_upload(ov_vbo, gl_bytes_of(ov_n * 6 * OV_FLOATS), ov_buf, GPU_STREAM)
+  var font = ov_font
+  if font == 0 { font = ov_white }
+  r3d_bind_2d(ov_prog, "u_font", 1, font)
   var last = -1
   var clipped = false
   for i in 0 .. ov_nr {
     let o = i * OV_RANGE_W
     let t = ov_ranges[o]
-    if t != last {
-      r3d_bind_2d(ov_prog, "u_tex", 0, t)
-      var is_font = F_ZERO
-      if t == ov_font { is_font = F_ONE }
-      u_f(gpu_uniform(ov_prog, "u_is_font"), is_font)
-      last = t
-    }
+    if t != last { r3d_bind_2d(ov_prog, "u_tex", 0, t);  last = t }
     if ov_ranges[o + 5] > 0 {
       clipped = true
       gpu_scissor(ov_ranges[o + 3], ov_ranges[o + 4], ov_ranges[o + 5], ov_ranges[o + 6])
@@ -227,7 +227,13 @@ function ov_end() -> void {
   gpu_depth_test(true)
   ov_open = false
 }
+# Text and flat panels never end a draw: the font atlas stays bound beside the image texture and each
+# vertex says which it reads (ov_voff). Only a different image texture closes the range. A panel and
+# its label used to alternate the white and font textures, and the HUD was 77-91 draws a frame.
 function ov_use_tex(t: int) -> void {
+  if t != 0 and t == ov_font { ov_mode = 1;  ov_voff = fi(4);  return }
+  if t == ov_white { ov_mode = 2;  ov_voff = fi(8);  return }
+  ov_mode = 0;  ov_voff = F_ZERO
   if t != ov_tex { ov_close_range();  ov_tex = t }
 }
 
@@ -235,7 +241,7 @@ function ov_use_tex(t: int) -> void {
 function ov_vert(k: int, x: int, y: int, u: int, v: int, r: int, g: int, b: int, a: int) -> void {
   let o = k * OV_FLOATS
   gl_put_bits(ov_buf, o, x);  gl_put_bits(ov_buf, o + 1, y)
-  gl_put_bits(ov_buf, o + 2, u);  gl_put_bits(ov_buf, o + 3, v)
+  gl_put_bits(ov_buf, o + 2, u);  gl_put_bits(ov_buf, o + 3, f_add(v, ov_voff))
   gl_put_bits(ov_buf, o + 4, r);  gl_put_bits(ov_buf, o + 5, g);  gl_put_bits(ov_buf, o + 6, b);  gl_put_bits(ov_buf, o + 7, a)
 }
 # a textured quad, float-bit pixel corners and uvs

packages/ludic.render3d/shaders/overlay.frag

@@ -1,14 +1,20 @@
-// 2D overlay: a texture times a colour; the font atlas is white glyphs on alpha
+// 2D overlay: an image texture, the font atlas (white glyphs on alpha) or a flat colour, times a
+// colour. Which one is the vertex's own: v carries 4 x the mode (0 image, 1 font, 2 flat) on top of
+// its real coordinate, so text, panels and an image's quads share a draw (overlay.ludic, ov_use_tex).
 in vec2 v_uv;
 in vec4 v_col;
 uniform sampler2D u_tex;
-uniform float u_is_font;
+uniform sampler2D u_font;
 out vec4 o_color;
 void main() {
-  vec4 t = texture(u_tex, v_uv);
-  if (u_is_font > 0.5) {
-    o_color = vec4(v_col.rgb, v_col.a * t.a);
+  float mode = floor((v_uv.y + 0.5) * 0.25);
+  vec2 uv = vec2(v_uv.x, v_uv.y - 4.0 * mode);
+  if (mode > 1.5) {
+    o_color = v_col;
+  } else if (mode > 0.5) {
+    o_color = vec4(v_col.rgb, v_col.a * texture(u_font, uv).a);
   } else {
+    vec4 t = texture(u_tex, uv);
     o_color = vec4(v_col.rgb * t.rgb, v_col.a * t.a);
   }
 }

packages/ludic.render3d/shaders/spv/manifest.txt

@@ -1771,7 +1771,7 @@ U 1b654972 vert u_screen 0 vec2 1 0
 I 1b654972 a_pos 0 vec2
 I 1b654972 a_uv 1 vec2
 I 1b654972 a_col 2 vec4
-B 1b654972 frag 1 768
+B 1b654972 frag 0 764
 U 1b654972 frag u_cascade_vp 0 mat4 5 64
 U 1b654972 frag u_cascade_split 320 float 5 16
 U 1b654972 frag u_cascade_range 400 float 5 16
@@ -1800,14 +1800,14 @@ U 1b654972 frag u_ts_on 748 float 1 0
 U 1b654972 frag u_force_cascade 752 int 1 0
 U 1b654972 frag u_cloud_shadow 756 float 1 0
 U 1b654972 frag u_time 760 float 1 0
-U 1b654972 frag u_is_font 764 float 1 0
 T 1b654972 u_brdf 2
-T 1b654972 u_irradiance 3
-T 1b654972 u_prefilter 4
-T 1b654972 u_shadow 5
-T 1b654972 u_tershadow 6
-T 1b654972 u_tex 7
-T 1b654972 u_ts_height 8
+T 1b654972 u_font 3
+T 1b654972 u_irradiance 4
+T 1b654972 u_prefilter 5
+T 1b654972 u_shadow 6
+T 1b654972 u_tershadow 7
+T 1b654972 u_tex 8
+T 1b654972 u_ts_height 9
 P 1fde9cd2 skin.vert model.frag 
 B 1fde9cd2 vert 0 3344
 U 1fde9cd2 vert u_model 0 mat4 1 0