ForgePatch/src/main/java/net/minecraftforge/client/model/ItemTextureQuadConverter.java

package net.minecraftforge.client.model;

import com.google.common.collect.Lists;

import net.minecraft.client.renderer.texture.TextureAtlasSprite;
import net.minecraft.client.renderer.vertex.VertexFormat;
import net.minecraft.util.EnumFacing;
import net.minecraftforge.client.model.pipeline.UnpackedBakedQuad;
import net.minecraftforge.common.model.TRSRTransformation;

import javax.vecmath.Vector4f;

import java.util.List;

public final class ItemTextureQuadConverter
{
    private ItemTextureQuadConverter()
    {
        // non-instantiable
    }

    /**
     * Takes a texture and converts it into BakedQuads.
     * The conversion is done by scanning the texture horizontally and vertically and creating "strips" of the texture.
     * Strips that are of the same size and follow each other are converted into one bigger quad.
     * </br>
     * The resulting list of quads is the texture represented as a list of horizontal OR vertical quads,
     * depending on which creates less quads. If the amount of quads is equal, horizontal is preferred.
     *
     * @param format
     * @param template The input texture to convert
     * @param sprite   The texture whose UVs shall be used   @return The generated quads.
     */
    public static List<UnpackedBakedQuad> convertTexture(VertexFormat format, TRSRTransformation transform, TextureAtlasSprite template, TextureAtlasSprite sprite, float z, EnumFacing facing, int color)
    {
        List<UnpackedBakedQuad> horizontal = convertTextureHorizontal(format, transform, template, sprite, z, facing, color);
        List<UnpackedBakedQuad> vertical = convertTextureVertical(format, transform, template, sprite, z, facing, color);

        return horizontal.size() >= vertical.size() ? horizontal : vertical;
    }

    /**
     * Scans a texture and converts it into a list of horizontal strips stacked on top of each other.
     * The height of the strips is as big as possible.
     */
    public static List<UnpackedBakedQuad> convertTextureHorizontal(VertexFormat format, TRSRTransformation transform, TextureAtlasSprite template, TextureAtlasSprite sprite, float z, EnumFacing facing, int color)
    {
        int w = template.getIconWidth();
        int h = template.getIconHeight();
        float wScale = 16f / (float)w;
        float hScale = 16f / (float)h;
        int[] data = template.getFrameTextureData(0)[0];
        List<UnpackedBakedQuad> quads = Lists.newArrayList();

        // the upper left x-position of the current quad
        int start = -1;
        for (int y = 0; y < h; y++)
        {
            for (int x = 0; x < w; x++)
            {
                // current pixel
                int pixel = data[y * w + x];

                // no current quad but found a new one
                if (start < 0 && isVisible(pixel))
                {
                    start = x;
                }
                // got a current quad, but it ends here
                if (start >= 0 && !isVisible(pixel))
                {
                    // we now check if the visibility of the next row matches the one fo the current row
                    // if they are, we can extend the quad downwards
                    int endY = y + 1;
                    boolean sameRow = true;
                    while (sameRow)
                    {
                        for (int i = 0; i < w; i++)
                        {
                            int px1 = data[y * w + i];
                            int px2 = data[endY * w + i];
                            if (isVisible(px1) != isVisible(px2))
                            {
                                sameRow = false;
                                break;
                            }
                        }
                        if (sameRow)
                        {
                            endY++;
                        }
                    }

                    // create the quad
                    quads.add(genQuad(format, transform,
                                      (float)start * wScale,
                                      (float)y * hScale,
                                      (float)x * wScale,
                                      (float)endY * hScale,
                                      z, sprite, facing, color));

                    // update Y if all the rows match. no need to rescan
                    if (endY - y > 1)
                    {
                        y = endY - 1;
                    }
                    // clear current quad
                    start = -1;
                }
            }
        }

        return quads;
    }

    /**
     * Scans a texture and converts it into a list of vertical strips stacked next to each other from left to right.
     * The width of the strips is as big as possible.
     */
    public static List<UnpackedBakedQuad> convertTextureVertical(VertexFormat format, TRSRTransformation transform, TextureAtlasSprite template, TextureAtlasSprite sprite, float z, EnumFacing facing, int color)
    {
        int w = template.getIconWidth();
        int h = template.getIconHeight();
        float wScale = 16f / (float)w;
        float hScale = 16f / (float)h;
        int[] data = template.getFrameTextureData(0)[0];
        List<UnpackedBakedQuad> quads = Lists.newArrayList();

        // the upper left y-position of the current quad
        int start = -1;
        for (int x = 0; x < w; x++)
        {
            for (int y = 0; y < h; y++)
            {
                // current pixel
                int pixel = data[y * w + x];

                // no current quad but found a new one
                if (start < 0 && isVisible(pixel))
                {
                    start = y;
                }
                // got a current quad, but it ends here
                if (start >= 0 && !isVisible(pixel))
                {
                    // we now check if the visibility of the next column matches the one fo the current row
                    // if they are, we can extend the quad downwards
                    int endX = x + 1;
                    boolean sameColumn = true;
                    while (sameColumn)
                    {
                        for (int i = 0; i < h; i++)
                        {
                            int px1 = data[i * w + x];
                            int px2 = data[i * w + endX];
                            if (isVisible(px1) != isVisible(px2))
                            {
                                sameColumn = false;
                                break;
                            }
                        }
                        if (sameColumn)
                        {
                            endX++;
                        }
                    }

                    // create the quad
                    quads.add(genQuad(format, transform,
                                      (float)x * wScale,
                                      (float)start * hScale,
                                      (float)endX * wScale,
                                      (float)y * hScale,
                                      z, sprite, facing, color));

                    // update X if all the columns match. no need to rescan
                    if (endX - x > 1)
                    {
                        x = endX - 1;
                    }
                    // clear current quad
                    start = -1;
                }
            }
        }

        return quads;
    }

    // true if alpha != 0
    private static boolean isVisible(int color)
    {
        return (color >> 24 & 255) > 0;
    }

    /**
     * Generates a Front/Back quad for an itemmodel. Therefore only supports facing NORTH and SOUTH.
     * Coordinates are [0,16] to match the usual coordinates used in TextureAtlasSprites
     */
    public static UnpackedBakedQuad genQuad(VertexFormat format, TRSRTransformation transform, float x1, float y1, float x2, float y2, float z, TextureAtlasSprite sprite, EnumFacing facing, int color)
    {
        float u1 = sprite.getInterpolatedU(x1);
        float v1 = sprite.getInterpolatedV(y1);
        float u2 = sprite.getInterpolatedU(x2);
        float v2 = sprite.getInterpolatedV(y2);

        x1 /= 16f;
        y1 /= 16f;
        x2 /= 16f;
        y2 /= 16f;

        float tmp = y1;
        y1 = 1f - y2;
        y2 = 1f - tmp;

        return putQuad(format, transform, facing, sprite, color, x1, y1, x2, y2, z, u1, v1, u2, v2);
    }

    private static UnpackedBakedQuad putQuad(VertexFormat format, TRSRTransformation transform, EnumFacing side, TextureAtlasSprite sprite, int color,
                                             float x1, float y1, float x2, float y2, float z,
                                             float u1, float v1, float u2, float v2)
    {
        side = side.getOpposite();
        UnpackedBakedQuad.Builder builder = new UnpackedBakedQuad.Builder(format);
        builder.setQuadTint(-1);
        builder.setQuadOrientation(side);
        builder.setTexture(sprite);

        if (side == EnumFacing.NORTH)
        {
            putVertex(builder, format, transform, side, x1, y1, z, u1, v2, color);
            putVertex(builder, format, transform, side, x2, y1, z, u2, v2, color);
            putVertex(builder, format, transform, side, x2, y2, z, u2, v1, color);
            putVertex(builder, format, transform, side, x1, y2, z, u1, v1, color);
        } else
        {
            putVertex(builder, format, transform, side, x1, y1, z, u1, v2, color);
            putVertex(builder, format, transform, side, x1, y2, z, u1, v1, color);
            putVertex(builder, format, transform, side, x2, y2, z, u2, v1, color);
            putVertex(builder, format, transform, side, x2, y1, z, u2, v2, color);
        }
        return builder.build();
    }

    private static void putVertex(UnpackedBakedQuad.Builder builder, VertexFormat format, TRSRTransformation transform, EnumFacing side,
                                  float x, float y, float z, float u, float v, int color)
    {
        Vector4f vec = new Vector4f();
        for (int e = 0; e < format.getElementCount(); e++)
        {
            switch (format.getElement(e).getUsage())
            {
                case POSITION:
                    if (transform == TRSRTransformation.identity())
                    {
                        builder.put(e, x, y, z, 1);
                    }
                    // only apply the transform if it's not identity
                    else
                    {
                        vec.x = x;
                        vec.y = y;
                        vec.z = z;
                        vec.w = 1;
                        transform.getMatrix().transform(vec);
                        builder.put(e, vec.x, vec.y, vec.z, vec.w);
                    }
                    break;
                case COLOR:
                    float r = ((color >> 16) & 0xFF) / 255f; // red
                    float g = ((color >> 8) & 0xFF) / 255f; // green
                    float b = ((color >> 0) & 0xFF) / 255f; // blue
                    float a = ((color >> 24) & 0xFF) / 255f; // alpha
                    builder.put(e, r, g, b, a);
                    break;
                case UV:
                    if (format.getElement(e).getIndex() == 0)
                    {
                        builder.put(e, u, v, 0f, 1f);
                        break;
                    }
                case NORMAL:
                    builder.put(e, (float) side.getFrontOffsetX(), (float) side.getFrontOffsetY(), (float) side.getFrontOffsetZ(), 0f);
                    break;
                default:
                    builder.put(e);
                    break;
            }
        }
    }
}