corkscrew.cpp

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#include "fl/corkscrew.h"
#include "fl/algorithm.h"
#include "fl/math.h"
#include "fl/splat.h"
 
#define TWO_PI (PI * 2.0)
 
namespace fl {
 
void generateMap(const Corkscrew::Input &input, CorkscrewOutput &output);
 
void generateMap(const Corkscrew::Input &input, CorkscrewOutput &output) {
    // Calculate circumference per turn from height and total angle
    float circumferencePerTurn = input.totalHeight * TWO_PI / input.totalAngle;
 
    // Calculate vertical segments based on number of turns
    // For a single turn (2π), we want exactly 1 vertical segment
    // For two turns (4π), we want exactly 2 vertical segments
    uint16_t verticalSegments = round(input.totalAngle / TWO_PI);
 
    // Calculate width based on LED density per turn
    float ledsPerTurn = static_cast<float>(input.numLeds) / verticalSegments;
 
    // Determine cylindrical dimensions
    output.height = verticalSegments;
    output.width = ceil(ledsPerTurn);
 
    output.mapping.clear();
 
    // If numLeds is specified, use that for mapping size instead of grid
    if (input.numLeds > 0) {
        output.mapping.reserve(input.numLeds);
 
        // Generate LED mapping based on numLeds
        for (uint16_t i = 0; i < input.numLeds; ++i) {
            // Calculate position along the corkscrew (0.0 to 1.0)
            float position = static_cast<float>(i) / (input.numLeds - 1);
 
            // Calculate angle and height
            float angle = position * input.totalAngle;
            float height = position * verticalSegments;
 
            // Calculate circumference position
            float circumference = fmodf(angle * circumferencePerTurn / TWO_PI,
                                        circumferencePerTurn);
 
            // Store the mapping
            output.mapping.push_back({circumference, height});
        }
    } else {
        // Original grid-based mapping
        output.mapping.reserve(output.width * output.height);
 
        // Corrected super sampling step size
        float thetaStep = 0.5f / output.width;
        float hStep = 0.5f / output.height;
 
        // Precompute angle per segment
        float anglePerSegment = input.totalAngle / verticalSegments;
 
        // Loop over cylindrical pixels
        for (uint16_t h = 0; h < output.height; ++h) {
            float segmentOffset = input.offsetCircumference * h;
            for (uint16_t w = 0; w < output.width; ++w) {
                vec2f sample = {0, 0};
                // 2x2 supersampling
                for (uint8_t ssH = 0; ssH < 2; ++ssH) {
                    for (uint8_t ssW = 0; ssW < 2; ++ssW) {
                        float theta =
                            (w + 0.5f + ssW * thetaStep) / output.width;
                        float height = (h + 0.5f + ssH * hStep) / output.height;
 
                        // Corkscrew projection (θ,h)
                        float corkscrewTheta =
                            theta * TWO_PI + anglePerSegment * h;
                        float corkscrewH = height * verticalSegments;
 
                        // Apply circumference offset
                        float corkscrewCircumference = fmodf(
                            corkscrewTheta * circumferencePerTurn / TWO_PI +
                                segmentOffset,
                            circumferencePerTurn);
 
                        // Accumulate samples
                        sample.x += corkscrewCircumference;
                        sample.y += corkscrewH;
                    }
                }
 
                // Average the supersampled points
                sample.x *= 0.25f;
                sample.y *= 0.25f;
 
                output.mapping.push_back(sample);
            }
        }
    }
 
    // Apply inversion if requested
    if (input.invert) {
        fl::reverse(output.mapping.begin(), output.mapping.end());
    }
}
 
 
Corkscrew::Corkscrew(const Corkscrew::Input &input) : mInput(input) {
    fl::generateMap(mInput, mOutput);
}
 
vec2f Corkscrew::at(uint16_t i) const {
    if (i >= mOutput.mapping.size()) {
        // Handle out-of-bounds access, possibly by returning a default value
        return vec2f(0, 0);
    }
    // Convert the float position to integer
    const vec2f &position = mOutput.mapping[i];
    return position;
}
 
Tile2x2_u8 Corkscrew::at_splat(uint16_t i) const {
    if (i >= mOutput.mapping.size()) {
        // Handle out-of-bounds access, possibly by returning a default
        // Tile2x2_u8
        return Tile2x2_u8();
    }
    // Use the splat function to convert the vec2f to a Tile2x2_u8
    return splat(mOutput.mapping[i]);
}
 
size_t Corkscrew::size() const { return mOutput.mapping.size(); }
 
CorkscrewOutput Corkscrew::generateMap(const Input &input) {
    CorkscrewOutput output;
    fl::generateMap(input, output);
    return output;
}
 
} // namespace fl