From 7ff8576bc9f805b908e9a57d46724efe95f7f8b0 Mon Sep 17 00:00:00 2001
From: Kirigaya <1193466151@qq.com>
Date: Sat, 24 Aug 2024 22:50:11 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E4=BF=AE=E6=94=B9=E9=AB=98?=
 =?UTF-8?q?=E5=BA=A6=E5=AF=BC=E8=87=B4=E6=B8=B2=E6=9F=93=E5=99=A8=E4=B8=8D?=
 =?UTF-8?q?=E5=AF=B9=E9=BD=90=20|=20=E5=AE=8C=E6=88=90=E9=98=B6=E6=A2=AF?=
 =?UTF-8?q?=E7=8A=B6=E7=9A=84=E6=B8=B2=E6=9F=93?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/components/toolbar/signal-modal.vue   |  21 +++-
 src/hook/wave-view/render-shader.js       |   2 +-
 src/hook/wave-view/render-values.js       |  65 +++++++---
 src/hook/wave-view/render-wave.js         |  96 ++++++++++++---
 src/hook/wave-view/toolbar/renderModal.js | 143 ++++++++++++++++++----
 src/hook/wave-view/y-offset-update.js     |  19 +--
 6 files changed, 278 insertions(+), 68 deletions(-)

diff --git a/src/components/toolbar/signal-modal.vue b/src/components/toolbar/signal-modal.vue
index fcc8904..530fb44 100644
--- a/src/components/toolbar/signal-modal.vue
+++ b/src/components/toolbar/signal-modal.vue
@@ -1,7 +1,7 @@
 <template>
     <div class="">
         <el-radio-group v-model="signalModal"
-            @click="onRadioClick"
+            @change="onSignalModalUpdate"
         >
             <!-- 数字模式 -->
             <el-radio-button :label="0">
@@ -14,7 +14,7 @@
                 <span class="iconfont icon-common-digital"></span>
                 </el-tooltip>
             </el-radio-button>
-            <!-- 折现模拟 -->
+            <!-- 阶梯模拟 -->
             <el-radio-button :label="1">
                 <el-tooltip
                     effect="dark"
@@ -23,7 +23,7 @@
                     raw-content
                 ><span class="iconfont icon-ladder-analog"></span></el-tooltip>
             </el-radio-button>
-            <!-- 阶梯模拟 -->
+            <!-- 折线模拟 -->
             <el-radio-button :label="2">
                 <el-tooltip
                     effect="dark"
@@ -49,6 +49,20 @@ const { t } = useI18n();
 
 const signalModal = ref(0);
 
+function onSignalModalUpdate() {
+    const links = globalLookup.sidebarSelectedWireLinks;
+    if (links.size > 0) {
+        const modal = signalModal.value;
+        // 更新渲染选项
+        for (const link of links) {
+            globalLookup.setRenderOption(link, 'renderModal', modal);
+            globalLookup.waveRender.resetVertice(link);
+        }
+        
+        // 重新渲染
+        globalLookup.render();
+    }
+}
 
 function getOneSelectLink() {
     let selectedLink = undefined;
@@ -60,7 +74,6 @@ function getOneSelectLink() {
 }
 
 
-
 watch(globalLookup.sidebarSelectedWireLinks, () => {
     const link = getOneSelectLink();
     if (link) {
diff --git a/src/hook/wave-view/render-shader.js b/src/hook/wave-view/render-shader.js
index 9e15965..cbdd046 100644
--- a/src/hook/wave-view/render-shader.js
+++ b/src/hook/wave-view/render-shader.js
@@ -52,7 +52,7 @@ void main() {
     // 偏移包括三部分：用户滚动时发生的全局位移、为了设置线宽发生的位移、与 scale 无关的额外位移
     float offsetX = offset.x + float(ws.x) + float(shift.x);
     float offsetY = offset.y + float(ws.y) + float(shift.y);
-    
+
     gl_Position = vec4(
         posX * scale.x + offsetX,
         posY * scale.y + offsetY,
diff --git a/src/hook/wave-view/render-values.js b/src/hook/wave-view/render-values.js
index c822549..c60c7ae 100644
--- a/src/hook/wave-view/render-values.js
+++ b/src/hook/wave-view/render-values.js
@@ -8,7 +8,7 @@ import vline from './vline';
 import getX from './get-x';
 import vlineStylo from './vline-stylo';
 import getLabel from './get-label';
-import { globalLookup } from '../global.js';
+import { globalLookup, globalSetting } from '../global.js';
 
 const defs = ['defs',
     ['linearGradient', { id: 'valid' },
@@ -33,7 +33,49 @@ const defs = ['defs',
     })
 ];
 
+/**
+ * @param {string} link
+ * @returns {number} 
+ */
+function getVecRenderModal(link) {
+    const renderOptions = globalLookup.currentSignalRenderOptions;
+    if (renderOptions.has(link)) {
+        const option = renderOptions.get(link);
+        if (typeof option.renderModal === 'number') {
+            return option.renderModal;
+        }
+    }
+    return 0;
+}
 
+/**
+ * @description 根据 link 得到对应的 value 渲染模式
+ * @param {*} link 
+ */
+function addVecRenderItem(link) {
+    const link2CurrentWires = globalLookup.link2CurrentWires;
+    const modal = getVecRenderModal(link);
+    if (modal === 0) {
+        const signal = link2CurrentWires.get(link);
+        return {
+            name: signal.name,
+            kind: signal.kind,
+            ref: signal.link
+        }
+    } else if (modal === 1) {
+        return {
+            name: '',
+            kind: '',
+            ref: ''
+        }
+    } else {
+        return {
+            name: '',
+            kind: '',
+            ref: ''
+        }
+    }
+}
 
 
 /**
@@ -52,15 +94,10 @@ function* renderValues(desc, pstate) {
     
     const currentWires = desc.currentWires;
     const renderSignals = [];
-    const link2CurrentWires = globalLookup.link2CurrentWires;
     for (const view of globalLookup.currentWiresRenderView) {
         if (view.renderType === 0) {
-            const realSignal = link2CurrentWires.get(view.signalInfo.link);
-            renderSignals.push({
-                name: realSignal.name,
-                kind: realSignal.kind,
-                ref: realSignal.link
-            });
+            const realSignal = addVecRenderItem(view.signalInfo.link);
+            renderSignals.push(realSignal);
         } else {
             // 如果是组，需要渲染空白的一行
             renderSignals.push({
@@ -71,21 +108,17 @@ function* renderValues(desc, pstate) {
             // 如果没有关闭，把所有子节点加入其中
             if (view.groupInfo.collapse === false) {
                 for (const child of view.children) {
-                    const realSignal = link2CurrentWires.get(child.signalInfo.link);
-                    renderSignals.push({
-                        name: realSignal.name,
-                        kind: realSignal.kind,
-                        ref: realSignal.link
-                    });
+                    const realSignal = addVecRenderItem(view.signalInfo.link);
+                    renderSignals.push(realSignal);
                 }
             }
         }
     }
 
     
-
+    const lineHeightExtra = (globalSetting.displaySignalHeight - 30) / 2;
     const ilen = height / yStep;
-    const iskip = yOffset / yStep;
+    const iskip = (yOffset - lineHeightExtra) / yStep;
 
     const ml = genSVG(width, height - topBarHeight - botBarHeight);
 
diff --git a/src/hook/wave-view/render-wave.js b/src/hook/wave-view/render-wave.js
index 5478e07..baf7e01 100644
--- a/src/hook/wave-view/render-wave.js
+++ b/src/hook/wave-view/render-wave.js
@@ -2,7 +2,14 @@ import { globalSetting, globalStyle } from '../global';
 
 import { gl_Colors, gl_Shifts, gl_Shifts_for_bar, gl_WidthShifts, barShift, getRatio, screenHeightPixel, maskColorIndexOffset, posYFactor, glslInputLength, prettyPrint } from './render-utils.js';
 import { vertexShader, fragmentShader } from './render-shader.js';
-import { renderAsBit, renderAsCommonDigital, renderAsLadderAnalog } from './toolbar/renderModal';
+import { renderAsBit, renderAsCommonDigital, renderAsLadderAnalog, renderAsLineAnalog } from './toolbar/renderModal';
+
+/**
+ * @description
+ * @typedef {Object} VecRenderNumberVertices
+ * @property {number[]} lineVertices
+ * @property {number[]} maskVertices
+ */
 
 // const { ChangoItem } = require('./types.d.ts');
 
@@ -149,6 +156,42 @@ class WebGL2WaveRender {
         };
     }
 
+    /**
+     * @param {GlobalLookup} lookup
+     * @param {string} link
+     * @returns {number} 
+     */
+    getVecRenderModal(lookup, link) {
+        const renderOptions = lookup.currentSignalRenderOptions;
+        if (renderOptions.has(link)) {
+            const option = renderOptions.get(link);
+            if (typeof option.renderModal === 'number') {
+                return option.renderModal;
+            }
+        }
+        return 0;
+    }
+
+    /**
+     * @param {GlobalLookup} lookup
+     * @param {string} link
+     * @param {Array<string | number>} wave 
+     * @param { number } time 
+     * @returns {(lookup: GlobalLookup, link: string, wave: number[], time: number) => VecRenderNumberVertices}
+     */
+    selectVecRenderFn(lookup, link, wave, time) {
+        const modal = this.getVecRenderModal(lookup, link);
+        switch (modal) {
+            case 0:
+                return renderAsCommonDigital;
+            case 1:
+                return renderAsLadderAnalog;
+            case 2:
+                return renderAsLineAnalog;
+            default:
+                return renderAsCommonDigital;
+        }
+    }
 
     /**
      * @param {string} link
@@ -161,8 +204,8 @@ class WebGL2WaveRender {
      */
     makeVecVertex(link, wave, time, debug = false) {
         const lookup = this.globalLookup;
-        
-        const { lineVertices, maskVertices } = renderAsCommonDigital(lookup, link, wave, time);
+        const vecRenderFn = this.selectVecRenderFn(lookup, link, wave, time);
+        const { lineVertices, maskVertices } = vecRenderFn(lookup, link, wave, time);
 
         if (debug) {
             console.log(lineVertices);
@@ -326,7 +369,7 @@ class WebGL2WaveRender {
         const plugins = this.plugins;
         
         pstate.yStep = globalSetting.displaySignalHeight + globalStyle.sideBarItemMargin;
-        pstate.yDuty = (1 - 2 * globalStyle.sideBarItemMargin / this.pstate.yStep) * 0.95;
+        pstate.yDuty = (1 - 2 * globalStyle.sideBarItemMargin / pstate.yStep) * 0.95;
         
         document.body.style.setProperty('--vcd-render-padding',  pstate.topBarHeight + 'px');
         const canvasHeight = pstate.height - pstate.topBarHeight - pstate.botBarHeight;
@@ -411,8 +454,12 @@ class WebGL2WaveRender {
                     return;
                 }
 
-                const offsetX = 2 * xOffset / canvasWidth - 1;
-                const offsetY = 2 * (yOffset - yStep * index) / canvasHeight + 1;
+                // 区间映射公式，将 [a, b] 内的数字映射到 [c, d] 中
+                // $f(x) = \frac{d - c}{b - a} (x - a) + c$
+                const offsetX = 2 / canvasWidth * xOffset - 1;
+
+                const lineHeightExtra = (globalSetting.displaySignalHeight - 30) / 2;
+                const offsetY = 2 / canvasHeight * (yOffset - yStep * index - lineHeightExtra) + 1;
                 gl.uniform2f(webglLocation.offset, offsetX, offsetY);
 
                 // 根据 lineVao 进行绘制            
@@ -423,7 +470,7 @@ class WebGL2WaveRender {
                 const maskVertices = maskVerticesMap.get(id);
 
                 if (signal.size === 1) {
-                    // 如果是 width 为 1 的
+                    // 如果是 bit
                     gl.uniform2fv(webglLocation.shifts, gl_Shifts);
                     gl.bindVertexArray(signalItem.lineVao);
                     gl.drawArrays(gl.TRIANGLE_STRIP, 0, lineVertices.length / glslInputLength);
@@ -431,15 +478,34 @@ class WebGL2WaveRender {
                     gl.bindVertexArray(signalItem.maskVao);
                     gl.drawArrays(gl.TRIANGLES, 0, maskVertices.length / glslInputLength);
                 } else {
-                    // 如果是 width 大于 1 的
-                    gl.uniform2fv(webglLocation.shifts, gl_Shifts_for_bar);
-                    gl.bindVertexArray(signalItem.lineVao);
-                    gl.drawArrays(gl.TRIANGLES, 0, lineVertices.length / glslInputLength);
-
-                    gl.bindVertexArray(signalItem.maskVao);
-                    gl.drawArrays(gl.TRIANGLES, 0, maskVertices.length / glslInputLength);
+                    // 如果是 vec，根据设定的渲染模式和进行设置
+                    const vecRenderModal = _this.getVecRenderModal(globalLookup, signal.link);
+                    if (vecRenderModal === 0) {
+                        // 普通数字渲染模式
+                        gl.uniform2fv(webglLocation.shifts, gl_Shifts_for_bar);
+                        gl.bindVertexArray(signalItem.lineVao);
+                        gl.drawArrays(gl.TRIANGLES, 0, lineVertices.length / glslInputLength);
+    
+                        gl.bindVertexArray(signalItem.maskVao);
+                        gl.drawArrays(gl.TRIANGLES, 0, maskVertices.length / glslInputLength);
+                    } else if (vecRenderModal === 1) {
+                        // 梯形渲染模式
+                        gl.uniform2fv(webglLocation.shifts, gl_Shifts_for_bar);
+                        gl.bindVertexArray(signalItem.lineVao);
+                        gl.drawArrays(gl.TRIANGLE_STRIP, 0, lineVertices.length / glslInputLength);
+    
+                        gl.bindVertexArray(signalItem.maskVao);
+                        gl.drawArrays(gl.TRIANGLES, 0, maskVertices.length / glslInputLength);
+                    } else {
+                        // 折线渲染模式
+                        gl.uniform2fv(webglLocation.shifts, gl_Shifts_for_bar);
+                        gl.bindVertexArray(signalItem.lineVao);
+                        gl.drawArrays(gl.TRIANGLES, 0, lineVertices.length / glslInputLength);
+    
+                        gl.bindVertexArray(signalItem.maskVao);
+                        gl.drawArrays(gl.TRIANGLES, 0, maskVertices.length / glslInputLength);
+                    }
                 }
-
             }
 
             plugins.map(fn => fn(globalLookup, pstate, elements));
diff --git a/src/hook/wave-view/toolbar/renderModal.js b/src/hook/wave-view/toolbar/renderModal.js
index f635264..a934df8 100644
--- a/src/hook/wave-view/toolbar/renderModal.js
+++ b/src/hook/wave-view/toolbar/renderModal.js
@@ -29,7 +29,7 @@
  */
 
 import { globalLookup } from "@/hook/global";
-import { maskColorIndexOffset, posYFactor } from "../render-utils";
+import { maskColorIndexOffset, posYFactor, prettyPrint } from "../render-utils";
 import { hexToSignedInt } from "./renderFormat";
 
 
@@ -130,15 +130,15 @@ function makeWidthShiftIndexByPoints(p0, p1, p2) {
     return 0;
 }
 
+
 /**
  * 
  * @param {string} link
  * @param {Array<string | number>} wave 
  * @param { number } time 
- * @param {(link: string, wave: number[], time: number) => BitRenderTempStruct} renderParamMaker
  * @returns {VecRenderNumberVertices} 
  */
-function renderBlockWave(link, wave, time, renderParamMaker) {
+export function renderAsBit(link, wave, time) {
     const length = wave.length;
     // 先将节点数据转化为裁剪空间的坐标
     const perspectivePoints = [];
@@ -153,8 +153,8 @@ function renderBlockWave(link, wave, time, renderParamMaker) {
         const value1 = currentWave[1];
         const value2 = nextWave[1];
 
-        const renderParam1 = renderParamMaker(link, currentWave, time);
-        const renderParam2 = renderParamMaker(link, nextWave, time);
+        const renderParam1 = makeBitRenderParam(link, currentWave, time);
+        const renderParam2 = makeBitRenderParam(link, nextWave, time);
 
         if (i === 0) {
             perspectivePoints.push({ x: t1, y: renderParam1.y, color: renderParam1.color });
@@ -250,17 +250,6 @@ function renderBlockWave(link, wave, time, renderParamMaker) {
     return { lineVertices, maskVertices };
 }
 
-/**
- * 
- * @param {string} link
- * @param {Array<string | number>} wave 
- * @param { number } time 
- * @returns {VecRenderNumberVertices} 
- */
-export function renderAsBit(link, wave, time) {
-    return renderBlockWave(link, wave, time, makeBitRenderParam);
-}
-
 /**
  * @description Digital
  * @param {GlobalLookup} lookup
@@ -462,10 +451,6 @@ export function renderAsLadderAnalog(lookup, link, wave, time) {
     const { maxVal, minVal } = getMaxMinByFormat(link, wave, time, formatCode, width);
     const coordinateTransform = getMappingFunc(formatCode, maxVal, minVal);
 
-    const length = wave.length;
-    const lineVertices = [];
-    const maskVertices = [];
-
     function makeLadderAnalogRenderParam(link, wave, time) {        
         const [t1, val, mask] = wave;
 
@@ -478,7 +463,6 @@ export function renderAsLadderAnalog(lookup, link, wave, time) {
         const numVal = explainAsJSNumber(formatCode, val, width);
         // 此时的 y 是一个 -1 到 1 的浮点数，因为 VAO 我设置了 Int
         const y = coordinateTransform(numVal);
-        console.log(t1, y);
         const colorParam = { y, color: 5 };
 
         if (renderOptions.has(link)) {
@@ -490,8 +474,115 @@ export function renderAsLadderAnalog(lookup, link, wave, time) {
 
         return colorParam;
     }
+
+    const length = wave.length;
+    // 先将节点数据转化为裁剪空间的坐标
+    const perspectivePoints = [];
+
+    for (let i = 0; i < length; ++ i) {
+        // const currentWave = wave[(i === 0) ? 0 : (i - 1)];
+        const currentWave = wave[i];
+        const nextWave = (i === (length - 1)) ? wave[i] : wave[i + 1];
+
+        const t1 = currentWave[0];
+        const t2 = (i === (length - 1)) ? time : wave[i + 1][0];
+        const value1 = currentWave[1];
+        const value2 = nextWave[1];
+
+        const renderParam1 = makeLadderAnalogRenderParam(link, currentWave, time);
+        const renderParam2 = makeLadderAnalogRenderParam(link, nextWave, time);
+
+        if (i === 0) {
+            perspectivePoints.push({ x: t1, y: renderParam1.y, color: renderParam1.color });
+            perspectivePoints.push({ x: t2, y: renderParam1.y, color: renderParam1.color });
+        } else {
+            const lastPoint = perspectivePoints[perspectivePoints.length - 1];
+            if ((lastPoint.y !== renderParam1.y) || (lastPoint.color !== renderParam1.color)) {
+                perspectivePoints.push({ x: t1, y: renderParam1.y, color: renderParam1.color });
+            }
+            if ((renderParam1.y !== renderParam2.y) || (renderParam1.color !== renderParam2.color)) {
+                perspectivePoints.push({ x: t2, y: renderParam1.y, color: renderParam1.color });
+            }
+        }
+    }
+
+    // 确保最后一个点延申到了 time
+    const lastPoint = perspectivePoints[perspectivePoints.length - 1];
+    if (lastPoint.x < time) {
+        perspectivePoints.push({ x: time, y: lastPoint.y, color: lastPoint.color });
+    }
+
+    // 计算出传入 shader 四元组数组
+    // 四元组： (x, yshift_index, color_index, width_shift_index)
+    const pointNum = perspectivePoints.length;
+    const lineVertices = [];
+    const maskVertices = [];
+
     
-    return renderBlockWave(link, wave, time, makeLadderAnalogRenderParam);
+    // 制作 lineVertices
+    for (let i = 0; i < pointNum; ++ i) {
+        // p0: 上一个点
+        // p1: 当前的点
+        // p2: 下一个点
+        const p0 = perspectivePoints[i - 1];
+        const p1 = perspectivePoints[i];
+        const p2 = perspectivePoints[i + 1];
+
+        const wsIndex = makeWidthShiftIndexByPoints(p0, p1, p2);
+
+        if (wsIndex === undefined) {
+            console.log(p0, p1, p2);
+        }
+
+        lineVertices.push(
+            // uvec2 pos; uvec3 control;
+            p1.x, p1.y * posYFactor, 0, wsIndex,           p1.color,
+            p1.x, p1.y * posYFactor, 0, (wsIndex + 4) % 8, p1.color
+        );
+
+        // 防止颜色不同导致单个图元内出现两个颜色，这会引发shader的渐变
+        if (p2 !== undefined && p1.color !== p2.color) {
+            lineVertices.push(
+                // uvec2 pos; uvec3 control;
+                p1.x, p1.y * posYFactor, 0, wsIndex,           p2.color,
+                p1.x, p1.y * posYFactor, 0, (wsIndex + 4) % 8, p2.color,
+            );
+        }
+    }
+
+    // 制作 maskVertices
+    for (let i = 0; i < pointNum; ++ i) {
+        const p1 = perspectivePoints[i];
+
+        // 开头就有一条线
+        if (i === 0 && p1.y === 1) {
+            while (perspectivePoints[++ i] && perspectivePoints[i].y === 1);
+            // 回退
+            if (-- i > 0) {
+                // 四元组： (x, yshift_index, color_index, width_shift_index)
+                const rectangleVertices = makeRectangleVertices(p1.x, 1, perspectivePoints[i].x, -1, p1.color + maskColorIndexOffset, 4);
+                // 三角图元画矩形
+                maskVertices.push(...rectangleVertices);
+                continue;
+            }
+        }
+
+        // 上升沿才使用
+        const p2 = perspectivePoints[i + 1];
+        const p3 = perspectivePoints[i + 2];
+
+        if (p1 === undefined || p2 === undefined || p3 === undefined) {
+            continue;
+        }
+        if (p2.y > -1) {
+            // 矩形的四个点
+            const rectangleVertices = makeRectangleVertices(p2.x, p2.y, p3.x, -1, p2.color + maskColorIndexOffset, 4);
+            // 三角图元画矩形
+            maskVertices.push(...rectangleVertices);
+        }
+    }
+
+    return { lineVertices, maskVertices };
 }
 
 /**
@@ -507,9 +598,13 @@ export function renderAsLineAnalog(lookup, link, wave, time) {
     const formatCode = getValFormatCode(lookup, link);
     const signal = lookup.link2CurrentWires.get(link);
     const width = signal.size;
-    
+
     const { maxVal, minVal } = getMaxMinByFormat(link, wave, time, formatCode, width);
-    
+    const coordinateTransform = getMappingFunc(formatCode, maxVal, minVal);
+
+    const length = wave.length;
+    const lineVertices = [];
+    const maskVertices = [];
 
 
 }
\ No newline at end of file
diff --git a/src/hook/wave-view/y-offset-update.js b/src/hook/wave-view/y-offset-update.js
index 31271de..841b25f 100644
--- a/src/hook/wave-view/y-offset-update.js
+++ b/src/hook/wave-view/y-offset-update.js
@@ -1,21 +1,24 @@
-import { globalStyle, globalLookup } from '../global';
+import { globalStyle, globalLookup, globalSetting } from '../global';
 
 const yOffsetUpdate = (pstate, nextOffsetYFn) => {
     let nextOffsetY = nextOffsetYFn();
     const { width, xOffset, xScale, time, sidebarWidth } = pstate;
 
+    nextOffsetY = nextOffsetY;
+
     const currentRenderHeight = globalLookup.currentWires.size * pstate.yStep;
     const canvasHeight = pstate.height - pstate.topBarHeight - pstate.botBarHeight;
     // console.log(currentRenderHeight, canvasHeight);
-    const maxOffsetX = Math.max(-20, currentRenderHeight - canvasHeight); // maximum offset
-    nextOffsetY = Math.min(nextOffsetY, maxOffsetX);
+    const maxOffsetY = Math.max(-20,
+                                currentRenderHeight - canvasHeight); // maximum offset
+    nextOffsetY = Math.min(nextOffsetY, maxOffsetY);
 
-    const minOffsetX = -20; // minimum offset
-    nextOffsetY = Math.max(nextOffsetY, minOffsetX);
+    const minOffsetY = -20; // minimum offset
+    nextOffsetY = Math.max(nextOffsetY, minOffsetY);
     
-    if (nextOffsetY === xOffset) {
-        return false; // exit without scroll
-    }
+    // if (nextOffsetY === xOffset) {
+    //     return false; // exit without scroll
+    // }
     
     pstate.oldYOffset = pstate.yOffset;
     pstate.yOffset = nextOffsetY;