corkscrew.cpp

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#include "fl/corkscrew.h"
#include "fl/algorithm.h"
#include "fl/assert.h"
#include "fl/math.h"
#include "fl/splat.h"
 
#include "fl/math_macros.h"
 
#define TWO_PI (PI * 2.0)
 
namespace fl {
 
void generateState(const Corkscrew::Input &input, CorkscrewState *output);
 
void generateState(const Corkscrew::Input &input, CorkscrewState *output) {
 
    // 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 = ceil(input.totalTurns);
 
    // Calculate width based on LED density per turn
    // float ledsPerTurn = static_cast<float>(input.numLeds) / verticalSegments;
 
    output->mapping.clear();
    output->width = 0; // we will change this below.
    output->height = 0;
 
    // If numLeds is specified, use that for mapping size instead of grid
    output->mapping.reserve(input.numLeds);
    // Generate LED mapping based on numLeds
    // Note that width_step should be 1.0f/float(input.numLeds) so last led in a
    // turn does not wrap around.
    const float width_step =
        1.0f / float(input.numLeds); // Corkscrew reaches max width on last led.
    const float height_step =
        1.0f /
        float(input.numLeds - 1); // Corkscrew reaches max height on last led.
    // const float led_width_factor = circumferencePerTurn / TWO_PI;
    const float length_per_turn = input.numLeds / input.totalTurns;
 
    for (uint16_t i = 0; i < input.numLeds; ++i) {
        // Calculate position along the corkscrew (0.0 to 1.0)
        const float i_f = static_cast<float>(i);
        const float alpha_width = i_f * width_step;
        const float alpha_height = i_f * height_step;
        const float width_before_mod = alpha_width * input.totalLength;
        const float height = alpha_height * input.totalHeight;
        const float width = fmodf(width_before_mod, length_per_turn);
        output->mapping.push_back({width, height});
    }
 
    if (!output->mapping.empty()) {
        float max_width = 0.0f;
        float max_height = 0.0f;
        for (const auto &point : output->mapping) {
            max_width = MAX(max_width, point.x);
            max_height = MAX(max_height, point.y);
        }
        output->width = static_cast<uint16_t>(ceilf(max_width)) + 1;
        output->height = static_cast<uint16_t>(ceilf(max_height)) + 1;
    }
 
    // Apply inversion if requested
    if (input.invert) {
        fl::reverse(output->mapping.begin(), output->mapping.end());
    }
}
 
Corkscrew::Corkscrew(const Corkscrew::Input &input) : mInput(input) {
    fl::generateState(mInput, &mState);
}
 
vec2f Corkscrew::at_exact(uint16_t i) const {
    if (i >= mState.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 = mState.mapping[i];
    return position;
}
 
 
Tile2x2_u8 Corkscrew::at_splat_extrapolate(float i) const {
    // To finish this, we need to handle wrap around.
    // To accomplish this we need a different data structure than the the
    // Tile2x2_u8.
    // 1. It will be called CorkscrewTile2x2_u8.
    // 2. The four alpha values will each contain the index the LED is at,
    // uint16_t.
    // 3. There will be no origin, each pixel in the tile will contain a
    // uint16_t origin. This is not supposed to be a storage format, but a
    // convenient pre-computed value for rendering.
    if (i >= mState.mapping.size()) {
        // Handle out-of-bounds access, possibly by returning a default
        // Tile2x2_u8
        FASTLED_ASSERT(false, "Out of bounds access in Corkscrew at_splat: "
                                  << i << " size: " << mState.mapping.size());
        return Tile2x2_u8();
    }
    // Use the splat function to convert the vec2f to a Tile2x2_u8
    float i_floor = floorf(i);
    float i_ceil = ceilf(i);
    if (ALMOST_EQUAL_FLOAT(i_floor, i_ceil)) {
        // If the index is the same, just return the splat of that index
        return splat(mState.mapping[static_cast<uint16_t>(i_floor)]);
    } else {
        // Interpolate between the two points and return the splat of the result
        vec2f pos1 = mState.mapping[static_cast<uint16_t>(i_floor)];
        vec2f pos2 = mState.mapping[static_cast<uint16_t>(i_ceil)];
 
        if (pos2.x < pos1.x) {
            // If the next point is on the other side of the cylinder, we need
            // to wrap it around and bring it back into the positive direction so we can construct a Tile2x2_u8 wrap with it.
            pos2.x += mState.width;
        }
 
        vec2f interpolated_pos =
            pos1 * (1.0f - (i - i_floor)) + pos2 * (i - i_floor);
        return splat(interpolated_pos);
    }
}
 
size_t Corkscrew::size() const { return mState.mapping.size(); }
 
Corkscrew::State Corkscrew::generateState(const Corkscrew::Input &input) {
    CorkscrewState output;
    fl::generateState(input, &output);
    return output;
}
 
 
 
Tile2x2_u8_wrap Corkscrew::at_wrap(float i) const {
    // This is a splatted pixel, but wrapped around the cylinder.
    // This is useful for rendering the corkscrew in a cylindrical way.
    Tile2x2_u8 tile = at_splat_extrapolate(i);
    return Tile2x2_u8_wrap(tile, mState.width, mState.height);
}
 
} // namespace fl