sdl ui backend

1 files changed, 18 insertions, 0 deletions

diff --git a/shaders/ui.frag.glsl b/shaders/ui.frag.glsl
new file mode 100644
index 00000000..2284fa0b
--- /dev/null
+++ b/shaders/ui.frag.glsl
@@ -0,0 +1,18 @@
+#version 450
+
+// Sample the glyph atlas (R = coverage 0..1) and mix the cell's bg up to its fg
+// by that coverage. Fully opaque: the swapchain is SDR, no blending needed.
+
+layout(set = 2, binding = 0) uniform sampler2D u_atlas;
+
+layout(location = 0) in vec2 v_uv;
+layout(location = 1) in vec3 v_fg;
+layout(location = 2) in vec3 v_bg;
+
+layout(location = 0) out vec4 o_col;
+
+void main() {
+    float a = texture(u_atlas, v_uv).r;
+    vec3 col = mix(v_bg, v_fg, a);
+    o_col = vec4(col, 1.0);
+}