|
1 /* |
|
2 * Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies). |
|
3 * All rights reserved. |
|
4 * This component and the accompanying materials are made available |
|
5 * under the terms of "Eclipse Public License v1.0" |
|
6 * which accompanies this distribution, and is available |
|
7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
|
8 * |
|
9 * Initial Contributors: |
|
10 * Nokia Corporation - initial contribution. |
|
11 * |
|
12 * Contributors: |
|
13 * |
|
14 * Description: Triangle filler. |
|
15 * |
|
16 */ |
|
17 |
|
18 |
|
19 // Include Files |
|
20 #include <e32std.h> |
|
21 #include "TMIDTriangleFiller.h" |
|
22 |
|
23 |
|
24 // LOCAL CONSTANTS AND MACROS |
|
25 |
|
26 |
|
27 |
|
28 // LOCAL FUNCTIONS |
|
29 |
|
30 void TMIDTriangleFiller::Construct(TInt aX1, TInt aY1, |
|
31 TInt aX2, TInt aY2, |
|
32 TInt aX3, TInt aY3) |
|
33 { |
|
34 iX1 = aX1 << KShift; |
|
35 iY1 = aY1 << KShift; |
|
36 iX2 = aX2 << KShift; |
|
37 iY2 = aY2 << KShift; |
|
38 iX3 = aX3 << KShift; |
|
39 iY3 = aY3 << KShift; |
|
40 |
|
41 if (iY1 > iY2) |
|
42 { |
|
43 // Swap P1 and P2 |
|
44 SwapPoints(iX1, iY1, iX2, iY2); |
|
45 } |
|
46 if (iY2 > iY3) |
|
47 { |
|
48 // Swap P2 and P3 |
|
49 SwapPoints(iX2, iY2, iX3, iY3); |
|
50 } |
|
51 if (iY1 > iY2) |
|
52 { |
|
53 // Swap P1 and P2 |
|
54 SwapPoints(iX1, iY1, iX2, iY2); |
|
55 } |
|
56 |
|
57 iNormalCase = EFalse; |
|
58 if (iY1 == iY2) |
|
59 { |
|
60 if (iY2 == iY3) |
|
61 { |
|
62 ConstructSingleLine(); |
|
63 } |
|
64 else |
|
65 { |
|
66 ConstructSpecialCaseOne(); |
|
67 } |
|
68 } |
|
69 else if (iY2 == iY3) |
|
70 { |
|
71 ConstructSpecialCaseTwo(); |
|
72 } |
|
73 else |
|
74 { |
|
75 ConstructNormalCase(); |
|
76 } |
|
77 iY1 = iY1 >> KShift; |
|
78 } |
|
79 |
|
80 |
|
81 |
|
82 void TMIDTriangleFiller::SecondHalf() |
|
83 { |
|
84 if (iLeftDelta == iDx13) |
|
85 { |
|
86 iRightDelta = iDx23; |
|
87 } |
|
88 else |
|
89 { |
|
90 iLeftDelta = iDx23; |
|
91 } |
|
92 |
|
93 |
|
94 iScanlines = (iY3 - iY2) >> KShift; |
|
95 iNormalCase = EFalse; |
|
96 } |
|
97 |
|
98 void TMIDTriangleFiller::ConstructNormalCase() |
|
99 { |
|
100 // The normal case: |
|
101 // 1 |
|
102 // /| |
|
103 // / | first half |
|
104 // / | dx12 < dx13 |
|
105 // 2/___|____ |
|
106 // \_ | |
|
107 // \_| second half |
|
108 // 3 |
|
109 |
|
110 // Calculate step values for edges |
|
111 iNormalCase = ETrue; |
|
112 iDx12 = (FPDIV((iX2 - iX1), (iY2 - iY1))); |
|
113 iDx23 = (FPDIV((iX3 - iX2), (iY3 - iY2))); |
|
114 iDx13 = (FPDIV((iX3 - iX1), (iY3 - iY1))); |
|
115 |
|
116 |
|
117 |
|
118 // Check which edge (13 or 12) is the left side edge |
|
119 if (iDx12 < iDx13) |
|
120 { |
|
121 iLeftDelta = iDx12; |
|
122 iRightDelta = iDx13; |
|
123 } |
|
124 else |
|
125 { |
|
126 iLeftDelta = iDx13; |
|
127 iRightDelta = iDx12; |
|
128 } |
|
129 |
|
130 |
|
131 |
|
132 // Initialize the span |
|
133 iSpanStart = iX1; |
|
134 iSpanStop = iX1; |
|
135 |
|
136 // Do the first half of the polygon ( 1-2 ) |
|
137 iScanlines = (iY2 - iY1) >> KShift; |
|
138 } |
|
139 |
|
140 void TMIDTriangleFiller::ConstructSingleLine() |
|
141 { |
|
142 iScanlines = 1; |
|
143 iSpanStart = Min(iX1, iX2); |
|
144 iSpanStart = Min(iSpanStart, iX3); |
|
145 |
|
146 iSpanStop = Max(iX1, iX2); |
|
147 iSpanStop = Max(iSpanStop, iX3); |
|
148 } |
|
149 |
|
150 void TMIDTriangleFiller::ConstructSpecialCaseOne() |
|
151 { |
|
152 // Special case: |
|
153 // 1________2 |
|
154 // \ / |
|
155 // \ / |
|
156 // \ / |
|
157 // \/ |
|
158 // 3 |
|
159 if (iX1 > iX2) |
|
160 { |
|
161 SwapPoints(iX1, iY1, iX2, iY2); |
|
162 } |
|
163 |
|
164 iDx13 = (FPDIV((iX3 - iX1), (iY3 - iY1))); |
|
165 iDx23 = (FPDIV((iX3 - iX2), (iY3 - iY2))); |
|
166 |
|
167 // check which edge is left edge |
|
168 if (iDx13 < iDx23) |
|
169 { |
|
170 iLeftDelta = iDx23; |
|
171 iRightDelta = iDx13; |
|
172 } |
|
173 else |
|
174 { |
|
175 iLeftDelta = iDx13; |
|
176 iRightDelta = iDx23; |
|
177 } |
|
178 |
|
179 // initialize span |
|
180 iSpanStart = iX1; |
|
181 iSpanStop = iX2; |
|
182 |
|
183 iScanlines = (iY3 - iY1) >> KShift; |
|
184 |
|
185 } |
|
186 void TMIDTriangleFiller::ConstructSpecialCaseTwo() |
|
187 { |
|
188 /* |
|
189 // Special case: |
|
190 // 1 |
|
191 // /\ |
|
192 // / \ |
|
193 // / \ |
|
194 // / \ |
|
195 //2--------3 |
|
196 */ |
|
197 |
|
198 // calculate slopes |
|
199 iDx12 = (FPDIV((iX2 - iX1), (iY2 - iY1))); |
|
200 iDx13 = (FPDIV((iX3 - iX1), (iY3 - iY1))); |
|
201 |
|
202 // check which edge is left edge |
|
203 if (iDx12 < iDx13) |
|
204 { |
|
205 iLeftDelta = iDx12; |
|
206 iRightDelta = iDx13; |
|
207 } |
|
208 else |
|
209 { |
|
210 iLeftDelta = iDx13; |
|
211 iRightDelta = iDx12; |
|
212 } |
|
213 |
|
214 // Initialize the span |
|
215 iSpanStart = iX1;// + iLeftDelta; |
|
216 iSpanStop = iX1;// + iRightDelta; |
|
217 |
|
218 iScanlines = (iY2 - iY1) >> KShift; |
|
219 } |
|
220 |
|
221 void TMIDTriangleFiller::GetNextPixelRun(TBool& aExists, TInt& aScanLine, |
|
222 TInt& aStart, TInt& aEnd) |
|
223 { |
|
224 aScanLine = iY1++; |
|
225 aStart = (iSpanStart >> KShift) + 1; |
|
226 aEnd = iSpanStop >> KShift; |
|
227 |
|
228 iSpanStart += iLeftDelta; |
|
229 iSpanStop += iRightDelta; |
|
230 aExists = ETrue; |
|
231 if (--iScanlines < 1) |
|
232 { |
|
233 if (iNormalCase) |
|
234 { |
|
235 SecondHalf(); |
|
236 } |
|
237 else |
|
238 { |
|
239 aExists = EFalse; |
|
240 } |
|
241 } |
|
242 } |
|
243 // End of File |
|
244 |