robert@464: /*
robert@464:  * vector_graphics.cpp
robert@464:  *
robert@464:  *  Created on: Nov 10, 2014
robert@464:  *      Author: parallels
robert@464:  */
robert@464: 
robert@464: #include <cmath>
robert@464: 
robert@464: // Draw a line between two points at a specified rate in
robert@464: // pixels per buffer sample. Indicate maximum available space.
robert@464: // Returns space used
robert@464: int renderLine(float x1, float y1, float x2, float y2, float speed,
robert@464: 			   float *buffer, int maxLength) {
robert@464: 	// Figure out length of line and therefore how many samples
robert@464: 	// are needed to represent it based on the speed (rounded to nearest int)
robert@464: 	float totalLineLength = sqrtf((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
robert@464: 	int samplesNeeded = floorf(totalLineLength / speed + 0.5);
robert@464: 
robert@464: 	// Now render into the buffer
robert@464: 	int length = 0;
robert@464: 	float scaleFactor = 1.0f / samplesNeeded;
robert@464: 	for(int n = 0; n < samplesNeeded; n++) {
robert@464: 		if(length >= maxLength - 1)
robert@464: 			return length;
robert@464: 		// X coordinate
robert@464: 		*buffer++ = x1 + (float)n * scaleFactor * (x2 - x1);
robert@464: 		// Y coordinate
robert@464: 		*buffer++ = y1 + (float)n * scaleFactor * (y2 - y1);
robert@464: 		length += 2;
robert@464: 	}
robert@464: 
robert@464: 	return length;
robert@464: }
robert@464: 
robert@464: // Draw an arc around a centre point at a specified rate of pixels
robert@464: // per buffer sample. Indicate maximum available space.
robert@464: // Returns space used
robert@464: int renderArc(float x, float y, float radius, float thetaMin, float thetaMax,
robert@464: 			  float speed, float *buffer, int maxLength) {
robert@464: 	// Figure out circumference of arc and therefore how many samples
robert@464: 	// are needed to represent it based on the speed (rounded to nearest int)
robert@464: 	float circumference = (thetaMax - thetaMin) * radius;
robert@464: 	int samplesNeeded = floorf(circumference / speed + 0.5);
robert@464: 
robert@464: 	// Now render into the buffer
robert@464: 	int length = 0;
robert@464: 	float scaleFactor = 1.0f / samplesNeeded;
robert@464: 	for(int n = 0; n < samplesNeeded; n++) {
robert@464: 		if(length >= maxLength - 1)
robert@464: 			return length;
robert@464: 		// Get current angle
robert@464: 		float theta = thetaMin + (float)n * scaleFactor * (thetaMax - thetaMin);
robert@464: 
robert@464: 		// Convert polar to cartesian coordinates
robert@464: 		*buffer++ = x + radius * cosf(theta);
robert@464: 		*buffer++ = y + radius * sinf(theta);
robert@464: 
robert@464: 		length += 2;
robert@464: 	}
robert@464: 
robert@464: 	return length;
robert@464: }
robert@464: 
robert@464: // Draw a single point for a specified number of frames
robert@464: void renderPoint(float x, float y, float *buffer, float length) {
robert@464: 	while(length > 0) {
robert@464: 		*buffer++ = x;
robert@464: 		*buffer++ = y;
robert@464: 		length--;
robert@464: 	}
robert@464: }