diff examples/10-Instruments/tank-wars/vector_graphics.cpp @ 493:a23d74e2f6cb prerelease

Minor changes to doxygen

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/10-Instruments/tank-wars/vector_graphics.cpp	Tue Jun 21 18:50:03 2016 +0100
@@ -0,0 +1,72 @@
+/*
+ * vector_graphics.cpp
+ *
+ *  Created on: Nov 10, 2014
+ *      Author: parallels
+ */
+
+#include <cmath>
+
+// Draw a line between two points at a specified rate in
+// pixels per buffer sample. Indicate maximum available space.
+// Returns space used
+int renderLine(float x1, float y1, float x2, float y2, float speed,
+			   float *buffer, int maxLength) {
+	// Figure out length of line and therefore how many samples
+	// are needed to represent it based on the speed (rounded to nearest int)
+	float totalLineLength = sqrtf((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
+	int samplesNeeded = floorf(totalLineLength / speed + 0.5);
+
+	// Now render into the buffer
+	int length = 0;
+	float scaleFactor = 1.0f / samplesNeeded;
+	for(int n = 0; n < samplesNeeded; n++) {
+		if(length >= maxLength - 1)
+			return length;
+		// X coordinate
+		*buffer++ = x1 + (float)n * scaleFactor * (x2 - x1);
+		// Y coordinate
+		*buffer++ = y1 + (float)n * scaleFactor * (y2 - y1);
+		length += 2;
+	}
+
+	return length;
+}
+
+// Draw an arc around a centre point at a specified rate of pixels
+// per buffer sample. Indicate maximum available space.
+// Returns space used
+int renderArc(float x, float y, float radius, float thetaMin, float thetaMax,
+			  float speed, float *buffer, int maxLength) {
+	// Figure out circumference of arc and therefore how many samples
+	// are needed to represent it based on the speed (rounded to nearest int)
+	float circumference = (thetaMax - thetaMin) * radius;
+	int samplesNeeded = floorf(circumference / speed + 0.5);
+
+	// Now render into the buffer
+	int length = 0;
+	float scaleFactor = 1.0f / samplesNeeded;
+	for(int n = 0; n < samplesNeeded; n++) {
+		if(length >= maxLength - 1)
+			return length;
+		// Get current angle
+		float theta = thetaMin + (float)n * scaleFactor * (thetaMax - thetaMin);
+
+		// Convert polar to cartesian coordinates
+		*buffer++ = x + radius * cosf(theta);
+		*buffer++ = y + radius * sinf(theta);
+
+		length += 2;
+	}
+
+	return length;
+}
+
+// Draw a single point for a specified number of frames
+void renderPoint(float x, float y, float *buffer, float length) {
+	while(length > 0) {
+		*buffer++ = x;
+		*buffer++ = y;
+		length--;
+	}
+}