package com.badlogic.gdx.graphics.g2d;


/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/


import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Color;
import com.badlogic.gdx.graphics.GL20;
import com.badlogic.gdx.graphics.Mesh;
import com.badlogic.gdx.graphics.Mesh.VertexDataType;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.VertexAttribute;
import com.badlogic.gdx.graphics.VertexAttributes.Usage;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;
import com.badlogic.gdx.math.Affine2;
import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.math.Matrix4;
import net.torvald.gdx.graphics.Cvec;

import java.nio.Buffer;

/** Draws batched quads using indices.
 *
 * This version of SpriteBatch assigns full non-packed float32 colour attribute to the vertices, as well as extra
 * float32 "colour" attribute under the name 'a_generic' (accessible via 'vec4 v_generic').
 *
 * Created by minjaesong on 2023-09-14.
 * @see Batch
 * @author mzechner
 * @author Nathan Sweet
 * @author CuriousTorvald
 */
public class UnpackedColourSpriteBatch extends SpriteBatch {
    /** @deprecated Do not use, this field is for testing only and is likely to be removed. Sets the {@link VertexDataType} to be
     *             used when gles 3 is not available, defaults to {@link VertexDataType#VertexArray}. */
    @Deprecated public static VertexDataType defaultVertexDataType = VertexDataType.VertexArray;

    private Mesh mesh;

    final float[] vertices;
    int idx = 0;
    Texture lastTexture = null;
    float invTexWidth = 0, invTexHeight = 0;

    boolean drawing = false;

    private final Matrix4 transformMatrix = new Matrix4();
    private final Matrix4 projectionMatrix = new Matrix4();
    private final Matrix4 combinedMatrix = new Matrix4();

    private boolean blendingDisabled = false;
    private int blendSrcFunc = GL20.GL_SRC_ALPHA;
    private int blendDstFunc = GL20.GL_ONE_MINUS_SRC_ALPHA;
    private int blendSrcFuncAlpha = GL20.GL_ONE;
    private int blendDstFuncAlpha = GL20.GL_ONE_MINUS_SRC_ALPHA;

    private final ShaderProgram shader;
    private ShaderProgram customShader = null;
    private boolean ownsShader;

    private final Color color = new Color(1, 1, 1, 1);
    private final Cvec generic = new Cvec(0);

    /** Number of render calls since the last {@link #begin()}. **/
    public int renderCalls = 0;

    /** Number of rendering calls, ever. Will not be reset unless set manually. **/
    public int totalRenderCalls = 0;

    /** The maximum number of sprites rendered in one batch so far. **/
    public int maxSpritesInBatch = 0;

    /** Constructs a new SpriteBatch with a size of 1000, one buffer, and the default shader.
     * @see SpriteBatch#SpriteBatch(int, ShaderProgram) */
    public UnpackedColourSpriteBatch () {
        this(1000, null);
    }

    /** Constructs a SpriteBatch with one buffer and the default shader.
     * @see SpriteBatch#SpriteBatch(int, ShaderProgram) */
    public UnpackedColourSpriteBatch (int size) {
        this(size, null);
    }

    private static final int VERTEX_ATTR_SIZE = 48;

    /** Constructs a new SpriteBatch. Sets the projection matrix to an orthographic projection with y-axis point upwards, x-axis
     * point to the right and the origin being in the bottom left corner of the screen. The projection will be pixel perfect with
     * respect to the current screen resolution.
     * <p>
     * The defaultShader specifies the shader to use. Note that the names for uniforms for this default shader are different than
     * the ones expect for shaders set with {@link #setShader(ShaderProgram)}. See {@link #createDefaultShader()}.
     * @param size The max number of sprites in a single batch. Max of 8191.
     * @param defaultShader The default shader to use. This is not owned by the SpriteBatch and must be disposed separately. */
    public UnpackedColourSpriteBatch (int size, ShaderProgram defaultShader) {
        super(size, (defaultShader == null) ? createDefaultShader() : defaultShader);

        // 32767 is max vertex index, so 32767 / 4 vertices per sprite = 8191 sprites max.
        if (size > 8191) throw new IllegalArgumentException("Can't have more than 8191 sprites per batch: " + size);

        VertexDataType vertexDataType = (Gdx.gl30 != null) ? VertexDataType.VertexBufferObjectWithVAO : defaultVertexDataType;

        mesh = new Mesh(vertexDataType, false, size * 4, size * 6,
                new VertexAttribute(Usage.Position, 2, "a_position"),
                new VertexAttribute(Usage.ColorUnpacked, 4, "a_color"),
                new VertexAttribute(Usage.TextureCoordinates, 2, "a_texCoord0"),
                new VertexAttribute(Usage.Generic, 4, "a_generic"));

        projectionMatrix.setToOrtho2D(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());

        vertices = new float[size * VERTEX_ATTR_SIZE];

        int len = size * 6;
        short[] indices = new short[len];
        short j = 0;
        for (int i = 0; i < len; i += 6, j += 4) {
            indices[i] = j;
            indices[i + 1] = (short)(j + 1);
            indices[i + 2] = (short)(j + 2);
            indices[i + 3] = (short)(j + 2);
            indices[i + 4] = (short)(j + 3);
            indices[i + 5] = j;
        }
        mesh.setIndices(indices);

        if (defaultShader == null) {
            shader = createDefaultShader();
            ownsShader = true;
        } else
            shader = defaultShader;
    }

    /** Returns a new instance of the default shader used by SpriteBatch for GL2 when no shader is specified. */
    static public ShaderProgram createDefaultShader () {
        String vertexShader = """
                #version 150

                in vec4 a_position;
                in vec4 a_color;
                in vec4 a_generic;
                in vec2 a_texCoord0;

                uniform mat4 u_projTrans;

                out vec4 v_color;
                out vec2 v_texCoords;
                out vec4 v_generic;

                void main() {
                    v_color = a_color;
                    v_texCoords = a_texCoord0;
                    v_generic = a_generic;
                    gl_Position = u_projTrans * a_position;
                }""";
        String fragmentShader = """
                #version 150
                 
                #ifdef GL_ES
                    precision mediump float;
                #endif
                
                in vec4 v_color;
                in vec4 v_generic;
                in vec2 v_texCoords;
                uniform sampler2D u_texture;
                out vec4 fragColor;
                
                void main() {
                    fragColor = v_color * texture(u_texture, v_texCoords);
                }""";

        ShaderProgram shader = new ShaderProgram(vertexShader, fragmentShader);
        if (!shader.isCompiled()) throw new IllegalArgumentException("Error compiling shader: " + shader.getLog());
        return shader;
    }

    @Override
    public void begin () {
        if (drawing) throw new IllegalStateException("SpriteBatch.end must be called before begin.");
        renderCalls = 0;

        Gdx.gl.glDepthMask(false);
        if (customShader != null)
            customShader.bind();
        else
            shader.bind();
        setupMatrices();

        drawing = true;
    }

    @Override
    public void end () {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before end.");
        if (idx > 0) flush();
        lastTexture = null;
        drawing = false;

        GL20 gl = Gdx.gl;
        gl.glDepthMask(true);
        if (isBlendingEnabled()) gl.glDisable(GL20.GL_BLEND);
    }

    @Override
    public void setColor (Color tint) {
        color.set(tint);
    }

    @Override
    public void setColor (float r, float g, float b, float a) {
        color.set(r, g, b, a);
    }

    @Override
    public Color getColor () {
        return color;
    }


    public void setGeneric (Cvec xyzw) {
        generic.set(xyzw);
    }

    public void setGeneric (float x, float y, float z, float w) {
        generic.set(x, y, z, w);
    }

    public Cvec getGeneric () {
        return generic;
    }

    @Override
    public void setPackedColor (float packedColor) {
        throw new UnsupportedOperationException();
    }

    @Override
    public float getPackedColor () {
        throw new UnsupportedOperationException();
    }

    private void appendVertices(float x1, float y1, float u1, float v1,
                                float x2, float y2, float u2, float v2,
                                float x3, float y3, float u3, float v3,
                                float x4, float y4, float u4, float v4) {

        int idx = this.idx;
        vertices[idx] = x1;
        vertices[idx +  1] = y1;
        vertices[idx +  2] = color.r;
        vertices[idx +  3] = color.g;
        vertices[idx +  4] = color.b;
        vertices[idx +  5] = color.a;
        vertices[idx +  6] = u1;
        vertices[idx +  7] = v1;
        vertices[idx +  8] = generic.r;
        vertices[idx +  9] = generic.g;
        vertices[idx + 10] = generic.b;
        vertices[idx + 11] = generic.a;

        vertices[idx + 12] = x2;
        vertices[idx + 13] = y2;
        vertices[idx + 14] = color.r;
        vertices[idx + 15] = color.g;
        vertices[idx + 16] = color.b;
        vertices[idx + 17] = color.a;
        vertices[idx + 18] = u2;
        vertices[idx + 19] = v2;
        vertices[idx + 20] = generic.r;
        vertices[idx + 21] = generic.g;
        vertices[idx + 22] = generic.b;
        vertices[idx + 23] = generic.a;

        vertices[idx + 24] = x3;
        vertices[idx + 25] = y3;
        vertices[idx + 26] = color.r;
        vertices[idx + 27] = color.g;
        vertices[idx + 28] = color.b;
        vertices[idx + 29] = color.a;
        vertices[idx + 30] = u3;
        vertices[idx + 31] = v3;
        vertices[idx + 32] = generic.r;
        vertices[idx + 33] = generic.g;
        vertices[idx + 34] = generic.b;
        vertices[idx + 35] = generic.a;

        vertices[idx + 36] = x4;
        vertices[idx + 37] = y4;
        vertices[idx + 38] = color.r;
        vertices[idx + 39] = color.g;
        vertices[idx + 40] = color.b;
        vertices[idx + 41] = color.a;
        vertices[idx + 42] = u4;
        vertices[idx + 43] = v4;
        vertices[idx + 44] = generic.r;
        vertices[idx + 45] = generic.g;
        vertices[idx + 46] = generic.b;
        vertices[idx + 47] = generic.a;
        this.idx = idx + 48;

    }

    @Override
    public void draw (Texture texture, float x, float y, float originX, float originY, float width, float height, float scaleX,
                      float scaleY, float rotation, int srcX, int srcY, int srcWidth, int srcHeight, boolean flipX, boolean flipY) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        if (texture != lastTexture)
            switchTexture(texture);
        else if (idx == vertices.length) //
            flush();

        // bottom left and top right corner points relative to origin
        final float worldOriginX = x + originX;
        final float worldOriginY = y + originY;
        float fx = -originX;
        float fy = -originY;
        float fx2 = width - originX;
        float fy2 = height - originY;

        // scale
        if (scaleX != 1 || scaleY != 1) {
            fx *= scaleX;
            fy *= scaleY;
            fx2 *= scaleX;
            fy2 *= scaleY;
        }

        // construct corner points, start from top left and go counter clockwise
        final float p1x = fx;
        final float p1y = fy;
        final float p2x = fx;
        final float p2y = fy2;
        final float p3x = fx2;
        final float p3y = fy2;
        final float p4x = fx2;
        final float p4y = fy;

        float x1;
        float y1;
        float x2;
        float y2;
        float x3;
        float y3;
        float x4;
        float y4;

        // rotate
        if (rotation != 0) {
            final float cos = MathUtils.cosDeg(rotation);
            final float sin = MathUtils.sinDeg(rotation);

            x1 = cos * p1x - sin * p1y;
            y1 = sin * p1x + cos * p1y;

            x2 = cos * p2x - sin * p2y;
            y2 = sin * p2x + cos * p2y;

            x3 = cos * p3x - sin * p3y;
            y3 = sin * p3x + cos * p3y;

            x4 = x1 + (x3 - x2);
            y4 = y3 - (y2 - y1);
        } else {
            x1 = p1x;
            y1 = p1y;

            x2 = p2x;
            y2 = p2y;

            x3 = p3x;
            y3 = p3y;

            x4 = p4x;
            y4 = p4y;
        }

        x1 += worldOriginX;
        y1 += worldOriginY;
        x2 += worldOriginX;
        y2 += worldOriginY;
        x3 += worldOriginX;
        y3 += worldOriginY;
        x4 += worldOriginX;
        y4 += worldOriginY;

        float u = srcX * invTexWidth;
        float v = (srcY + srcHeight) * invTexHeight;
        float u2 = (srcX + srcWidth) * invTexWidth;
        float v2 = srcY * invTexHeight;

        if (flipX) {
            float tmp = u;
            u = u2;
            u2 = tmp;
        }

        if (flipY) {
            float tmp = v;
            v = v2;
            v2 = tmp;
        }

        appendVertices(x1, y1, u, v,
                       x2, y2, u, v2,
                       x3, y3, u2, v2,
                       x4, y4, u2, v);
    }

    @Override
    public void draw (Texture texture, float x, float y, float width, float height, int srcX, int srcY, int srcWidth,
                      int srcHeight, boolean flipX, boolean flipY) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        if (texture != lastTexture)
            switchTexture(texture);
        else if (idx == vertices.length) //
            flush();

        float u = srcX * invTexWidth;
        float v = (srcY + srcHeight) * invTexHeight;
        float u2 = (srcX + srcWidth) * invTexWidth;
        float v2 = srcY * invTexHeight;
        final float fx2 = x + width;
        final float fy2 = y + height;

        if (flipX) {
            float tmp = u;
            u = u2;
            u2 = tmp;
        }

        if (flipY) {
            float tmp = v;
            v = v2;
            v2 = tmp;
        }

        appendVertices(x, y, u, v,
                       x, fy2, u, v2,
                       fx2, fy2, u2, v2,
                       fx2, y, u2, v2);
    }

    @Override
    public void draw (Texture texture, float x, float y, int srcX, int srcY, int srcWidth, int srcHeight) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        if (texture != lastTexture)
            switchTexture(texture);
        else if (idx == vertices.length) //
            flush();

        final float u = srcX * invTexWidth;
        final float v = (srcY + srcHeight) * invTexHeight;
        final float u2 = (srcX + srcWidth) * invTexWidth;
        final float v2 = srcY * invTexHeight;
        final float fx2 = x + srcWidth;
        final float fy2 = y + srcHeight;

        appendVertices(x, y, u, v,
                       x, fy2, u, v2,
                       fx2, fy2, u2, v2,
                       fx2, y, u2, v);
    }

    @Override
    public void draw (Texture texture, float x, float y, float width, float height, float u, float v, float u2, float v2) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        if (texture != lastTexture)
            switchTexture(texture);
        else if (idx == vertices.length) //
            flush();

        final float fx2 = x + width;
        final float fy2 = y + height;

        appendVertices(x, y, u, v,
                       x, fy2, u, v2,
                       fx2, fy2, u2, v2,
                       fx2, y, u2, v);
    }

    @Override
    public void draw (Texture texture, float x, float y) {
        draw(texture, x, y, texture.getWidth(), texture.getHeight());
    }

    @Override
    public void draw (Texture texture, float x, float y, float width, float height) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        if (texture != lastTexture)
            switchTexture(texture);
        else if (idx == vertices.length) //
            flush();

        final float fx2 = x + width;
        final float fy2 = y + height;
        final float u = 0;
        final float v = 1;
        final float u2 = 1;
        final float v2 = 0;

        appendVertices(x, y, u, v,
                       x, fy2, u, v2,
                       fx2, fy2, u2, v2,
                       fx2, y, u2, v);
    }

    @Override
    public void draw (Texture texture, float[] spriteVertices, int offset, int count) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        int verticesLength = vertices.length;
        int remainingVertices = verticesLength;
        if (texture != lastTexture)
            switchTexture(texture);
        else {
            remainingVertices -= idx;
            if (remainingVertices == 0) {
                flush();
                remainingVertices = verticesLength;
            }
        }
        int copyCount = Math.min(remainingVertices, count);

        System.arraycopy(spriteVertices, offset, vertices, idx, copyCount);
        idx += copyCount;
        count -= copyCount;
        while (count > 0) {
            offset += copyCount;
            flush();
            copyCount = Math.min(verticesLength, count);
            System.arraycopy(spriteVertices, offset, vertices, 0, copyCount);
            idx += copyCount;
            count -= copyCount;
        }
    }

    @Override
    public void draw (TextureRegion region, float x, float y) {
        draw(region, x, y, region.getRegionWidth(), region.getRegionHeight());
    }

    @Override
    public void draw (TextureRegion region, float x, float y, float width, float height) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        Texture texture = region.texture;
        if (texture != lastTexture) {
            switchTexture(texture);
        } else if (idx == vertices.length) //
            flush();

        final float fx2 = x + width;
        final float fy2 = y + height;
        final float u = region.u;
        final float v = region.v2;
        final float u2 = region.u2;
        final float v2 = region.v;

        appendVertices(x, y, u, v,
                       x, fy2, u, v2,
                       fx2, fy2, u2, v2,
                       fx2, y, u2, v);
    }

    @Override
    public void draw (TextureRegion region, float x, float y, float originX, float originY, float width, float height,
                      float scaleX, float scaleY, float rotation) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        Texture texture = region.texture;
        if (texture != lastTexture) {
            switchTexture(texture);
        } else if (idx == vertices.length) //
            flush();

        // bottom left and top right corner points relative to origin
        final float worldOriginX = x + originX;
        final float worldOriginY = y + originY;
        float fx = -originX;
        float fy = -originY;
        float fx2 = width - originX;
        float fy2 = height - originY;

        // scale
        if (scaleX != 1 || scaleY != 1) {
            fx *= scaleX;
            fy *= scaleY;
            fx2 *= scaleX;
            fy2 *= scaleY;
        }

        // construct corner points, start from top left and go counter clockwise
        final float p1x = fx;
        final float p1y = fy;
        final float p2x = fx;
        final float p2y = fy2;
        final float p3x = fx2;
        final float p3y = fy2;
        final float p4x = fx2;
        final float p4y = fy;

        float x1;
        float y1;
        float x2;
        float y2;
        float x3;
        float y3;
        float x4;
        float y4;

        // rotate
        if (rotation != 0) {
            final float cos = MathUtils.cosDeg(rotation);
            final float sin = MathUtils.sinDeg(rotation);

            x1 = cos * p1x - sin * p1y;
            y1 = sin * p1x + cos * p1y;

            x2 = cos * p2x - sin * p2y;
            y2 = sin * p2x + cos * p2y;

            x3 = cos * p3x - sin * p3y;
            y3 = sin * p3x + cos * p3y;

            x4 = x1 + (x3 - x2);
            y4 = y3 - (y2 - y1);
        } else {
            x1 = p1x;
            y1 = p1y;

            x2 = p2x;
            y2 = p2y;

            x3 = p3x;
            y3 = p3y;

            x4 = p4x;
            y4 = p4y;
        }

        x1 += worldOriginX;
        y1 += worldOriginY;
        x2 += worldOriginX;
        y2 += worldOriginY;
        x3 += worldOriginX;
        y3 += worldOriginY;
        x4 += worldOriginX;
        y4 += worldOriginY;

        final float u = region.u;
        final float v = region.v2;
        final float u2 = region.u2;
        final float v2 = region.v;

        appendVertices(x1, y1, u, v,
                       x2, y2, u, v2,
                       x3, y3, u2, v2,
                       x4, y4, u2, v);
    }

    @Override
    public void draw (TextureRegion region, float x, float y, float originX, float originY, float width, float height,
                      float scaleX, float scaleY, float rotation, boolean clockwise) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        Texture texture = region.texture;
        if (texture != lastTexture) {
            switchTexture(texture);
        } else if (idx == vertices.length) //
            flush();

        // bottom left and top right corner points relative to origin
        final float worldOriginX = x + originX;
        final float worldOriginY = y + originY;
        float fx = -originX;
        float fy = -originY;
        float fx2 = width - originX;
        float fy2 = height - originY;

        // scale
        if (scaleX != 1 || scaleY != 1) {
            fx *= scaleX;
            fy *= scaleY;
            fx2 *= scaleX;
            fy2 *= scaleY;
        }

        // construct corner points, start from top left and go counter clockwise
        final float p1x = fx;
        final float p1y = fy;
        final float p2x = fx;
        final float p2y = fy2;
        final float p3x = fx2;
        final float p3y = fy2;
        final float p4x = fx2;
        final float p4y = fy;

        float x1;
        float y1;
        float x2;
        float y2;
        float x3;
        float y3;
        float x4;
        float y4;

        // rotate
        if (rotation != 0) {
            final float cos = MathUtils.cosDeg(rotation);
            final float sin = MathUtils.sinDeg(rotation);

            x1 = cos * p1x - sin * p1y;
            y1 = sin * p1x + cos * p1y;

            x2 = cos * p2x - sin * p2y;
            y2 = sin * p2x + cos * p2y;

            x3 = cos * p3x - sin * p3y;
            y3 = sin * p3x + cos * p3y;

            x4 = x1 + (x3 - x2);
            y4 = y3 - (y2 - y1);
        } else {
            x1 = p1x;
            y1 = p1y;

            x2 = p2x;
            y2 = p2y;

            x3 = p3x;
            y3 = p3y;

            x4 = p4x;
            y4 = p4y;
        }

        x1 += worldOriginX;
        y1 += worldOriginY;
        x2 += worldOriginX;
        y2 += worldOriginY;
        x3 += worldOriginX;
        y3 += worldOriginY;
        x4 += worldOriginX;
        y4 += worldOriginY;

        float u1, v1, u2, v2, u3, v3, u4, v4;
        if (clockwise) {
            u1 = region.u2;
            v1 = region.v2;
            u2 = region.u;
            v2 = region.v2;
            u3 = region.u;
            v3 = region.v;
            u4 = region.u2;
            v4 = region.v;
        } else {
            u1 = region.u;
            v1 = region.v;
            u2 = region.u2;
            v2 = region.v;
            u3 = region.u2;
            v3 = region.v2;
            u4 = region.u;
            v4 = region.v2;
        }

        appendVertices(x1, y1, u1, v1,
                       x2, y2, u2, v2,
                       x3, y3, u3, v3,
                       x4, y4, u4, v4);
    }

    @Override
    public void draw (TextureRegion region, float width, float height, Affine2 transform) {
        if (!drawing) throw new IllegalStateException("SpriteBatch.begin must be called before draw.");

        float[] vertices = this.vertices;

        Texture texture = region.texture;
        if (texture != lastTexture) {
            switchTexture(texture);
        } else if (idx == vertices.length) {
            flush();
        }

        // construct corner points
        float x1 = transform.m02;
        float y1 = transform.m12;
        float x2 = transform.m01 * height + transform.m02;
        float y2 = transform.m11 * height + transform.m12;
        float x3 = transform.m00 * width + transform.m01 * height + transform.m02;
        float y3 = transform.m10 * width + transform.m11 * height + transform.m12;
        float x4 = transform.m00 * width + transform.m02;
        float y4 = transform.m10 * width + transform.m12;

        float u = region.u;
        float v = region.v2;
        float u2 = region.u2;
        float v2 = region.v;

        appendVertices(x1, y1, u, v,
                       x2, y2, u, v2,
                       x3, y3, u2, v2,
                       x4, y4, u2, v);
    }

    @Override
    public void flush () {
        if (idx == 0) return;

        renderCalls++;
        totalRenderCalls++;
        int spritesInBatch = idx / VERTEX_ATTR_SIZE;
        if (spritesInBatch > maxSpritesInBatch) maxSpritesInBatch = spritesInBatch;
        int count = spritesInBatch * 6;

        lastTexture.bind();
        Mesh mesh = this.mesh;
        mesh.setVertices(vertices, 0, idx);
        ((Buffer)mesh.getIndicesBuffer()).position(0);
        ((Buffer)mesh.getIndicesBuffer()).limit(count);

        if (blendingDisabled) {
            Gdx.gl.glDisable(GL20.GL_BLEND);
        } else {
            Gdx.gl.glEnable(GL20.GL_BLEND);
            if (blendSrcFunc != -1) Gdx.gl.glBlendFuncSeparate(blendSrcFunc, blendDstFunc, blendSrcFuncAlpha, blendDstFuncAlpha);
        }

        mesh.render(customShader != null ? customShader : shader, GL20.GL_TRIANGLES, 0, count);

        idx = 0;
    }

    @Override
    public void disableBlending () {
        if (blendingDisabled) return;
        flush();
        blendingDisabled = true;
    }

    @Override
    public void enableBlending () {
        if (!blendingDisabled) return;
        flush();
        blendingDisabled = false;
    }

    @Override
    public void setBlendFunction (int srcFunc, int dstFunc) {
        setBlendFunctionSeparate(srcFunc, dstFunc, srcFunc, dstFunc);
    }

    @Override
    public void setBlendFunctionSeparate (int srcFuncColor, int dstFuncColor, int srcFuncAlpha, int dstFuncAlpha) {
        if (blendSrcFunc == srcFuncColor && blendDstFunc == dstFuncColor && blendSrcFuncAlpha == srcFuncAlpha
                && blendDstFuncAlpha == dstFuncAlpha) return;
        flush();
        blendSrcFunc = srcFuncColor;
        blendDstFunc = dstFuncColor;
        blendSrcFuncAlpha = srcFuncAlpha;
        blendDstFuncAlpha = dstFuncAlpha;
    }

    @Override
    public int getBlendSrcFunc () {
        return blendSrcFunc;
    }

    @Override
    public int getBlendDstFunc () {
        return blendDstFunc;
    }

    @Override
    public int getBlendSrcFuncAlpha () {
        return blendSrcFuncAlpha;
    }

    @Override
    public int getBlendDstFuncAlpha () {
        return blendDstFuncAlpha;
    }

    @Override
    public void dispose () {
        mesh.dispose();
        if (ownsShader && shader != null) shader.dispose();
    }

    @Override
    public Matrix4 getProjectionMatrix () {
        return projectionMatrix;
    }

    @Override
    public Matrix4 getTransformMatrix () {
        return transformMatrix;
    }

    @Override
    public void setProjectionMatrix (Matrix4 projection) {
        if (drawing) flush();
        projectionMatrix.set(projection);
        if (drawing) setupMatrices();
    }

    @Override
    public void setTransformMatrix (Matrix4 transform) {
        if (drawing) flush();
        transformMatrix.set(transform);
        if (drawing) setupMatrices();
    }

    protected void setupMatrices () {
        combinedMatrix.set(projectionMatrix).mul(transformMatrix);
        if (customShader != null) {
            customShader.setUniformMatrix("u_projTrans", combinedMatrix);
            customShader.setUniformi("u_texture", 0);
        } else {
            shader.setUniformMatrix("u_projTrans", combinedMatrix);
            shader.setUniformi("u_texture", 0);
        }
    }

    protected void switchTexture (Texture texture) {
        flush();
        lastTexture = texture;
        invTexWidth = 1.0f / texture.getWidth();
        invTexHeight = 1.0f / texture.getHeight();
    }

    @Override
    public void setShader (ShaderProgram shader) {
        if (drawing) {
            flush();
        }
        customShader = shader;
        if (drawing) {
            if (customShader != null)
                customShader.bind();
            else
                this.shader.bind();
            setupMatrices();
        }
    }

    @Override
    public ShaderProgram getShader () {
        if (customShader == null) {
            return shader;
        }
        return customShader;
    }

    @Override
    public boolean isBlendingEnabled () {
        return !blendingDisabled;
    }

    public boolean isDrawing () {
        return drawing;
    }
}
