From 3ed69b49465f0b542d163da905dbc0864e19d5d8 Mon Sep 17 00:00:00 2001
From: Manuel Stoeckl <code@mstoeckl.com>
Date: Fri, 11 Nov 2022 22:53:06 -0500
Subject: render/vulkan: add support for RGB565 texture format

Since this does not have a matching _SRGB-type vulkan format, add a
new shader variant/pipeline to perform the sRGB->linear texture
conversion.
---
 render/vulkan/shaders/texture.frag | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

(limited to 'render/vulkan/shaders/texture.frag')

diff --git a/render/vulkan/shaders/texture.frag b/render/vulkan/shaders/texture.frag
index 0f9c52f1..15ef52af 100644
--- a/render/vulkan/shaders/texture.frag
+++ b/render/vulkan/shaders/texture.frag
@@ -9,8 +9,28 @@ layout(push_constant) uniform UBO {
 	layout(offset = 80) float alpha;
 } data;
 
+layout (constant_id = 0) const int TEXTURE_TRANSFORM = 0;
+
+#define TEXTURE_TRANSFORM_IDENTITY 0
+#define TEXTURE_TRANSFORM_SRGB 1
+
+float srgb_to_linear(float x) {
+	return max(x / 12.92, pow((x + 0.055) / 1.055, 2.4));
+}
+
 void main() {
-	out_color = textureLod(tex, uv, 0);
+	vec4 val = textureLod(tex, uv, 0);
+	if (TEXTURE_TRANSFORM == TEXTURE_TRANSFORM_SRGB) {
+		out_color = vec4(
+			srgb_to_linear(val.r),
+			srgb_to_linear(val.g),
+			srgb_to_linear(val.b),
+			val.a
+		);
+	} else { // TEXTURE_TRANSFORM_IDENTITY
+		out_color = val;
+	}
+
 	out_color *= data.alpha;
 }
 
-- 
cgit v1.2.3