From 08bef5db3ef6c3886ec19bf79a945e799a0ad477 Mon Sep 17 00:00:00 2001
From: ChrisRosser <41840611+ChrisRosser@users.noreply.github.com>
Date: Sat, 6 Apr 2024 18:09:15 +0100
Subject: [PATCH] first atttempt

---
 src/js/fc.js              |  2 ++
 src/js/tabs/pid_tuning.js | 52 ++++++++++++++++++++++++++++++---------
 2 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/src/js/fc.js b/src/js/fc.js
index 21c34a97c81..e573923c48c 100644
--- a/src/js/fc.js
+++ b/src/js/fc.js
@@ -250,6 +250,8 @@ const FC = {
             rcYawRate:                  0,
             rcPitchRate:                0,
             RC_PITCH_EXPO:              0,
+            throttleLimitType:          0,
+            throttleLimitPercent:       100,
             roll_rate_limit:            1998,
             pitch_rate_limit:           1998,
             yaw_rate_limit:             1998,
diff --git a/src/js/tabs/pid_tuning.js b/src/js/tabs/pid_tuning.js
index f709b180881..ae1185ee323 100644
--- a/src/js/tabs/pid_tuning.js
+++ b/src/js/tabs/pid_tuning.js
@@ -1719,22 +1719,30 @@ pid_tuning.initialize = function (callback) {
             Maths from: https://stackoverflow.com/questions/40918569/quadratic-bezier-curve-calculate-x-for-any-given-y
             */
             function getPosfromYBezier(y, startY, cpY, endY){
-            // y = (p0+p2-2p1)x^2 + 2(p1 - p2)x + p2
-            // 0 = (p0+p2-2p1)x^2 + 2(p1 - p2)x + (p2 - y)
-            // x = ( -2(p1 - p2) + sqrt( (2(p1 - p2))^2 - 4 * (p0+p2-2p1) * (p2 - y) ) ) / ( 2 * (p0+p2-2p1))
-                const a = startY+endY-2*cpY
-                const b = 2*(cpY - endY)
-                const c = endY - y
-                return (-b + Math.sqrt(Math.pow(b, 2) - 4 * a * c)) / (2 * a)
+            // y = (1-t)^2 * p0 + 2 * (1-t)*t*p1 + t^2 * p2
+            // y = (p2+p0-2p1)x^2 + 2(p1 - p0)x + p0
+            // 0 = (p2+p0-2p1)x^2 + 2(p1 - p0)x + (p0 - y)
+            const a = startY+endY-2*cpY
+            const b = 2*(cpY - startY)
+            const c = startY - y
+            return a==0? -c/b : (-b + Math.sqrt(Math.pow(b, 2) - 4 * a * c)) / (2 * a)
             }
 
             /* --- */
-
+            const THROTTLE_LIMIT_TYPES = {
+                OFF: 0,
+                SCALE: 1,
+                CLIP: 2,
+            };
             // let global validation trigger and adjust the values first
             const throttleMidE = $('.throttle input[name="mid"]');
             const throttleExpoE = $('.throttle input[name="expo"]');
+            const throttleLimitPercentE = $('.throttle_limit input[name="throttleLimitPercent"]');
+            const throttleLimitTypeE = $('.throttle_limit select[id="throttleLimitType"]');
             const mid = parseFloat(throttleMidE.val());
             const expo = parseFloat(throttleExpoE.val());
+            const throttleLimitPercent = parseInt(throttleLimitPercentE.val()) / 100;
+            const throttleLimitType = parseInt(throttleLimitTypeE.val());
             const throttleCurve = $('.throttle .throttle_curve canvas').get(0);
             const context = throttleCurve.getContext("2d");
 
@@ -1755,12 +1763,13 @@ pid_tuning.initialize = function (callback) {
             const canvasWidth = throttleCurve.width;
 
             // math magic by englishman
+            const curvescale = throttleLimitType === THROTTLE_LIMIT_TYPES.SCALE ? throttleLimitPercent : 1;
             const midx = canvasWidth * mid;
             const midxl = midx * 0.5;
             const midxr = (((canvasWidth - midx) * 0.5) + midx);
-            const midy = canvasHeight - (midx * (canvasHeight / canvasWidth));
-            const midyl = canvasHeight - ((canvasHeight - midy) * 0.5 *(expo + 1));
-            const midyr = (midy / 2) * (expo + 1);
+            const midy = (canvasHeight - (midx * (canvasHeight / canvasWidth))) * curvescale;
+            const midyl = (canvasHeight - ((canvasHeight - midy) * 0.5 *(expo + 1))) * curvescale;
+            const midyr = ((midy / 2) * (expo + 1)) * curvescale;
 
             let thrPercent = (FC.RC.channels[3] - 1000) / 1000,
                 thrpos = thrPercent <= mid
@@ -1771,6 +1780,27 @@ pid_tuning.initialize = function (callback) {
             context.clearRect(0, 0, canvasWidth, canvasHeight);
             context.beginPath();
             context.moveTo(0, canvasHeight);
+            if (throttleLimitType === THROTTLE_LIMIT_TYPES.CLIP){
+                const clippos = throttleLimitPercent <= midy
+                    ? getPosfromYBezier(throttleLimitPercent,canvasHeight,midyl, midy)
+                    : getPosfromYBezier(throttleLimitPercent,midy, midyl, 0);
+                if (throttleLimitPercent <= midyl){
+                    //first half
+                    lowerctrl = getQuadraticCurvePoint(0, canvasHeight, midxl, midyl, midx, midy, clippos/2);
+                    curveclip = getQuadraticCurvePoint(0, canvasHeight, midxl, midyl, midx, midy, clippos);
+                    context.quadraticCurveTo(lowerctrl.x, lowerctrl.y, curveclip.x, curveclip.y);
+                    context.moveTo(curveclip.x, curveclip.y);
+                    context.lineTo(canvasWidth, curveclip.y);
+                } else {
+                    context.quadraticCurveTo(midxl, midyl, midx, midy);
+                    context.moveTo(midx, midy);
+                    lowerctrl = getQuadraticCurvePoint(midx, midy, midxr, midyr, canvasWidth, 0, clippos/2);
+                    curveclip = getQuadraticCurvePoint(midx, midy, midxr, midyr, canvasWidth, 0, clippos);
+                    context.quadraticCurveTo(lowerctrl.x, lowerctrl.y, curveclip.x, curveclip.y);
+                    context.moveTo(curveclip.x, curveclip.y);
+                    context.lineTo(canvasWidth, curveclip.y);
+                }
+            }
             context.quadraticCurveTo(midxl, midyl, midx, midy);
             context.moveTo(midx, midy);
             context.quadraticCurveTo(midxr, midyr, canvasWidth, 0);