From 030724a9aea346e4a9843d5842fb28c6d6c4cf1a Mon Sep 17 00:00:00 2001
From: Peter Fors <peter.fors@mindkiller.com>
Date: Thu, 9 Oct 2025 22:07:52 +0200
Subject: Rearrangement and refactoring and optimizations and more accuracy

---
 gl_shader.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 gl_shader.c

(limited to 'gl_shader.c')

diff --git a/gl_shader.c b/gl_shader.c
new file mode 100644
index 0000000..f49f775
--- /dev/null
+++ b/gl_shader.c
@@ -0,0 +1,44 @@
+#include "gl_shader.h"
+
+//==============================================================
+//
+//                          CPU CODE
+//
+//==============================================================
+//              TONAL CONTROL CONSTANT GENERATION
+//--------------------------------------------------------------
+// Make sure to use same CRTS_MASK_* defines on CPU and GPU!!!!!
+//==============================================================
+/*
+ * dst - Output 4 float array.
+ *
+ * contrast - Increase contrast, ranges from,
+ *              1.0 = no change
+ *              2.0 = very strong contrast (over 2.0 for even more)
+ *
+ * saturation - Increase saturation, ranges from,
+ *                0.0 = no change
+ *                1.0 = increased saturation (over 1.0 for even more)
+ *
+ * thin, mask - Inputs shared between CrtsTone() and CrtsFilter()
+ *
+ */
+static void CrtsTone(float *dst, float contrast, float saturation, float thin, float mask) {
+//--------------------------------------------------------------
+#ifdef CRTS_MASK_NONE
+	mask = 1.0f;
+#endif
+//--------------------------------------------------------------
+#ifdef CRTS_MASK_GRILLE_LITE
+	// Normal R mask is {1.0,mask,mask}
+	// LITE   R mask is {mask,1.0,1.0}
+	mask = 0.5f + mask * 0.5f;
+#endif
+//--------------------------------------------------------------
+	float midOut = 0.18f / ((1.5f - thin) * (0.5f * mask + 0.5f));
+	float pMidIn = powf(0.18f, contrast);
+	dst[0] = contrast;
+	dst[1] = ((-pMidIn) + midOut) / ((1.0f - pMidIn) * midOut);
+	dst[2] = ((-pMidIn) * midOut + pMidIn) / (midOut * (-pMidIn) + midOut);
+	dst[3] = contrast + saturation;
+}
-- 
cgit v1.2.3