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engines/pegasus/neighborhood/mars/tractorbeam.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * Additional copyright for this file:
+ * Copyright (C) 1995-1997 Presto Studios, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "pegasus/pegasus.h"
+#include "pegasus/neighborhood/mars/constants.h"
+#include "pegasus/neighborhood/mars/tractorbeam.h"
+
+namespace Pegasus {
+
+TractorBeam::TractorBeam() : DisplayElement(kNoDisplayElement) {
+	setBounds(kShuttleTractorLeft, kShuttleTractorTop, kShuttleTractorLeft + kShuttleTractorWidth,
+			kShuttleTractorTop + kShuttleTractorHeight);
+	setDisplayOrder(kShuttleTractorBeamOrder);
+
+}
+
+static const int kHalfWidth = kShuttleTractorWidth >> 1;
+static const int kHalfHeight = kShuttleTractorHeight >> 1;
+
+static const int kW3Vert = kHalfHeight * kHalfHeight * kHalfHeight;
+static const int kW3Div2Vert = kW3Vert >> 1;
+
+static const int kW3Horiz = kHalfWidth * kHalfWidth * kHalfWidth;
+static const int kW3Div2Horiz = kW3Horiz >> 1;
+
+static const int kMaxLevel = 50;
+
+static const int kAVert = -2 * kMaxLevel;
+static const int kBVert = 3 * kMaxLevel * kHalfHeight;
+
+#define READ_PIXEL(ptr) \
+	if (screen->format.bytesPerPixel == 2) \
+		color = READ_UINT16(ptr); \
+	else \
+		color = READ_UINT32(ptr); \
+	screen->format.colorToRGB(color, r, g, b)
+
+#define WRITE_PIXEL(ptr) \
+	color = screen->format.RGBToColor(r, g, b); \
+	if (screen->format.bytesPerPixel == 2) \
+		WRITE_UINT16(ptr, color); \
+	else \
+		WRITE_UINT32(ptr, color)
+
+#define DO_BLEND(ptr) \
+	READ_PIXEL(ptr); \
+	g += (((0xff - g) * blendHoriz) >> 8); \
+	b += (((0xff - b) * blendHoriz) >> 8); \
+	WRITE_PIXEL(ptr)
+
+void TractorBeam::draw(const Common::Rect &) {
+	Graphics::Surface *screen = g_vm->_gfx->getWorkArea();
+
+	// Set up vertical DDA.
+	int blendVert = 0;
+	int dVert = 0;
+	int d1Vert = kAVert + kBVert;
+	int d2Vert = 6 * kAVert + 2 * kBVert;
+	int d3Vert = 6 * kAVert;
+
+	byte *rowPtrTop = (byte *)screen->getBasePtr(_bounds.left, _bounds.top);
+	byte *rowPtrBottom = (byte *)screen->getBasePtr(_bounds.left, _bounds.top + ((kHalfHeight << 1) - 1));
+
+	for (int y = kHalfHeight; y > 0; y--) {
+		// Set up horizontal DDA
+		int A = -2 * blendVert;
+		int B = 3 * blendVert * kHalfWidth;
+		int blendHoriz = 0;
+		int dHoriz = 0;
+		int d1Horiz = A + B;
+		int d2Horiz = 6 * A + 2 * B;
+		int d3Horiz = 6 * A;
+
+		byte *pTopLeft = rowPtrTop;
+		byte *pTopRight = rowPtrTop + (kHalfWidth * 2 - 1) * screen->format.bytesPerPixel;
+		byte *pBottomLeft = rowPtrBottom;
+		byte *pBottomRight = rowPtrBottom + (kHalfWidth * 2 - 1) * screen->format.bytesPerPixel;
+
+		for (int x = kHalfWidth; x > 0; x--) {
+			byte r, g, b;
+			uint32 color;
+
+			DO_BLEND(pTopLeft);
+			DO_BLEND(pTopRight);
+			DO_BLEND(pBottomLeft);
+			DO_BLEND(pBottomRight);
+
+			pTopLeft += screen->format.bytesPerPixel;
+			pBottomLeft += screen->format.bytesPerPixel;
+			pTopRight -= screen->format.bytesPerPixel;
+			pBottomRight -= screen->format.bytesPerPixel;
+
+			while (dHoriz > kW3Div2Horiz) {
+				blendHoriz++;
+				dHoriz -= kW3Horiz;
+			}
+
+			dHoriz += d1Horiz;
+			d1Horiz += d2Horiz;
+			d2Horiz += d3Horiz;
+		}
+
+		rowPtrTop += screen->pitch;
+		rowPtrBottom -= screen->pitch;
+
+		while (dVert > kW3Div2Vert) {
+			blendVert++;
+			dVert -= kW3Vert;
+		}
+
+		dVert += d1Vert;
+		d1Vert += d2Vert;
+		d2Vert += d3Vert;
+	}
+}
+
+} // End of namespace Pegasus