paysages3d/src/render/software/CanvasPixel.cpp

#include "CanvasPixel.h"

#include <cstring>

CanvasPixel::CanvasPixel() {
    count = 0;
    composite = COLOR_BLACK;
}

const CanvasFragment *CanvasPixel::getFrontFragment() const {
    if (count == 0) {
        return NULL;
    } else {
        return fragments + (count - 1);
    }
}

void CanvasPixel::reset() {
    count = 0;
    composite = COLOR_BLACK;
}

void CanvasPixel::pushFragment(const CanvasFragment &fragment) {
    if (count == 0) {
        fragments[0] = fragment;
        count = 1;
    } else {
        if (fragments[0].getOpaque() and fragment.getZ() <= fragments[0].getZ()) {
            // behind opaque fragment, don't bother
            return;
        }

        // find expected position
        int i = 0;
        while (i < count and fragment.getZ() >= fragments[i].getZ()) {
            i++;
        }

        if (i > 0 and fragments[i - 1].getZ() == fragment.getZ() and
            fragments[i - 1].getClient() == fragment.getClient()) {
            // Pixel already pushed by same client, don't do anything
            return;
        }

        if (fragment.getOpaque()) {
            // Discard fragments masked by the incoming opaque one
            if (i < count) {
                memmove(fragments + 1, fragments + i, sizeof(CanvasFragment) * (count - i));
                count -= i;
            } else {
                count = 1;
            }
            fragments[0] = fragment;
        } else {
            // Transparent pixel
            if (i < count) {
                // Need to make room for the incoming fragment
                if (count < MAX_FRAGMENTS_PER_PIXEL) {
                    memmove(fragments + i + 1, fragments + i, sizeof(CanvasFragment) * (count - i));
                    fragments[i] = fragment;
                    count++;
                }
            } else {
                if (count == MAX_FRAGMENTS_PER_PIXEL) {
                    // Replace nearest fragment
                    fragments[count - 1] = fragment;
                } else {
                    // Append
                    fragments[count] = fragment;
                    count++;
                }
            }
        }
    }

    updateComposite();
}

void CanvasPixel::updateComposite() {
    Color result(0.0, 0.0, 0.0, 1.0);
    for (int i = 0; i < count; i++) {
        result.mask(fragments[i].getColor());
    }
    composite = result;
}

void CanvasPixel::setComposite(const Color &color) {
    composite = color;
}