snuvi-engine/src/me/hammerle/snuviengine/api/FontRenderer.java

package me.hammerle.snuviengine.api;

import java.nio.ByteBuffer;
import me.hammerle.snuviengine.util.Rectangle;
import me.hammerle.snuviengine.util.Color;
import org.lwjgl.BufferUtils;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL15.*;
import static org.lwjgl.opengl.GL20.*;
import static org.lwjgl.opengl.GL30.*;

public class FontRenderer
{
    private final static Texture FONT_TEXTURE = new Texture("font.png");
    
    public static final char COLOR_CHAR = '&';
    
    private static final float[] COLORS = new float[128];
    private static final float[] DARK_COLORS = new float[128];
    
    private static final int FONT_SIZE = 8;
    private static final int LINE_STEP = 1;
    private static final float SHADOW_STEP = 1f;
    
    static
    {
        COLORS['0'] = Float.intBitsToFloat(Color.get(0, 0, 0));
        COLORS['1'] = Float.intBitsToFloat(Color.get(0, 0, 170));
        COLORS['2'] = Float.intBitsToFloat(Color.get(0, 170, 0));
        COLORS['3'] = Float.intBitsToFloat(Color.get(0, 170, 170));
        COLORS['4'] = Float.intBitsToFloat(Color.get(170, 0, 0));
        COLORS['5'] = Float.intBitsToFloat(Color.get(170, 0, 170));
        COLORS['6'] = Float.intBitsToFloat(Color.get(255, 170, 0));
        COLORS['7'] = Float.intBitsToFloat(Color.get(170, 170, 170));
        COLORS['8'] = Float.intBitsToFloat(Color.get(85, 85, 85));
        COLORS['9'] = Float.intBitsToFloat(Color.get(85, 85, 255));
        COLORS['a'] = Float.intBitsToFloat(Color.get(85, 255, 85));
        COLORS['b'] = Float.intBitsToFloat(Color.get(85, 255, 255));
        COLORS['c'] = Float.intBitsToFloat(Color.get(255, 85, 85));
        COLORS['d'] = Float.intBitsToFloat(Color.get(255, 85, 255));
        COLORS['e'] = Float.intBitsToFloat(Color.get(255, 255, 85));
        COLORS['f'] = Float.intBitsToFloat(Color.get(255, 255, 255));
        
        float factor = 0.5f;
        DARK_COLORS['0'] = Float.intBitsToFloat(Color.darken(Color.get(0, 0, 0), factor));
        DARK_COLORS['1'] = Float.intBitsToFloat(Color.darken(Color.get(0, 0, 170), factor));
        DARK_COLORS['2'] = Float.intBitsToFloat(Color.darken(Color.get(0, 170, 0), factor));
        DARK_COLORS['3'] = Float.intBitsToFloat(Color.darken(Color.get(0, 170, 170), factor));
        DARK_COLORS['4'] = Float.intBitsToFloat(Color.darken(Color.get(170, 0, 0), factor));
        DARK_COLORS['5'] = Float.intBitsToFloat(Color.darken(Color.get(170, 0, 170), factor));
        DARK_COLORS['6'] = Float.intBitsToFloat(Color.darken(Color.get(255, 170, 0), factor));
        DARK_COLORS['7'] = Float.intBitsToFloat(Color.darken(Color.get(170, 170, 170), factor));
        DARK_COLORS['8'] = Float.intBitsToFloat(Color.darken(Color.get(85, 85, 85), factor));
        DARK_COLORS['9'] = Float.intBitsToFloat(Color.darken(Color.get(85, 85, 255), factor));
        DARK_COLORS['a'] = Float.intBitsToFloat(Color.darken(Color.get(85, 255, 85), factor));
        DARK_COLORS['b'] = Float.intBitsToFloat(Color.darken(Color.get(85, 255, 255), factor));
        DARK_COLORS['c'] = Float.intBitsToFloat(Color.darken(Color.get(255, 85, 85), factor));
        DARK_COLORS['d'] = Float.intBitsToFloat(Color.darken(Color.get(255, 85, 255), factor));
        DARK_COLORS['e'] = Float.intBitsToFloat(Color.darken(Color.get(255, 255, 85), factor));
        DARK_COLORS['f'] = Float.intBitsToFloat(Color.darken(Color.get(255, 255, 255), factor));
    }
    
    private int vao;
    private int vbo;
    
    private float color;
    
    private ByteBuffer buffer = BufferUtils.createByteBuffer(OBJECT_LENGTH);
    
    private final static int MAX_LENGTH = 256;
    private final static int BUFFER_BYTE_LENGTH = 1024 * 1024;
    private final static int OBJECT_LENGTH = 120 * MAX_LENGTH * 2;
    
    private int offset = BUFFER_BYTE_LENGTH - OBJECT_LENGTH;
    
    protected FontRenderer()
    {
        Shader.addTask(() -> 
        {
            vao = glGenVertexArrays();
            vbo = glGenBuffers();

            GLHelper.glBindVertexArray(vao);
            GLHelper.glBindBuffer(vbo);
            
            glEnableVertexAttribArray(0);
            glEnableVertexAttribArray(1); 
            glEnableVertexAttribArray(2);
            
            glVertexAttribPointer(0, 2, GL_FLOAT, false, 20, 0);
            glVertexAttribPointer(1, 2, GL_FLOAT, false, 20, 8);
            glVertexAttribPointer(2, 4, GL_UNSIGNED_BYTE, true, 20, 16);
        });
    }

    private void addRectangle(float minX, float minY, char c)
    {
        float tMinX = (c & 0xF) / 16.0f;
        float tMinY = (c >> 4) / 16.0f;
        float tMaxX = tMinX + 0.0625f;
        float tMaxY = tMinY + 0.0625f;
        float maxX = minX + FONT_SIZE;
        float maxY = minY + FONT_SIZE;
        
        buffer.putFloat(minX);
        buffer.putFloat(maxY);        
        buffer.putFloat(tMinX);
        buffer.putFloat(tMaxY);
        buffer.putFloat(color);
        
        buffer.putFloat(minX);
        buffer.putFloat(minY);        
        buffer.putFloat(tMinX);
        buffer.putFloat(tMinY);
        buffer.putFloat(color);
        
        buffer.putFloat(maxX);
        buffer.putFloat(maxY);        
        buffer.putFloat(tMaxX);
        buffer.putFloat(tMaxY);
        buffer.putFloat(color);
        
        buffer.putFloat(maxX);
        buffer.putFloat(maxY);        
        buffer.putFloat(tMaxX);
        buffer.putFloat(tMaxY);
        buffer.putFloat(color);
        
        buffer.putFloat(minX);
        buffer.putFloat(minY);        
        buffer.putFloat(tMinX);
        buffer.putFloat(tMinY);
        buffer.putFloat(color);
        
        buffer.putFloat(maxX);
        buffer.putFloat(minY);        
        buffer.putFloat(tMaxX);
        buffer.putFloat(tMinY);
        buffer.putFloat(color);
    }
    
    public float drawString(float x, float y, boolean shadow, String s)
    {
        GLHelper.glBindBuffer(vbo);
        
        offset += OBJECT_LENGTH;
        if(offset + OBJECT_LENGTH >= BUFFER_BYTE_LENGTH)
        {
            offset = 0;
            glBufferData(GL_ARRAY_BUFFER, BUFFER_BYTE_LENGTH, GL_STREAM_DRAW);
        }
        buffer = glMapBufferRange(GL_ARRAY_BUFFER, offset, OBJECT_LENGTH, GL_MAP_WRITE_BIT | GL_MAP_UNSYNCHRONIZED_BIT, buffer);
        if(buffer == null)
        {
            return y;
        }
        
        if(shadow)
        {
            addString(x + SHADOW_STEP, y + SHADOW_STEP, DARK_COLORS, s);
        }
        y = addString(x, y, COLORS, s);
        
        buffer.flip();
        glUnmapBuffer(GL_ARRAY_BUFFER);
        
        GLHelper.glBindVertexArray(vao);
        FONT_TEXTURE.bindTexture();
        
        glDrawArrays(GL_TRIANGLES, offset / 20, buffer.limit() / 20);

        buffer.limit(buffer.capacity());
        return y;
    }

    private float addString(float x, float y, float[] colors, String s)
    {
        int l = Math.min(s.length(), MAX_LENGTH);
        
        float oldX = x;
        color = colors['f'];

        for(int pos = 0; pos < l; pos++)
        {
            char c = s.charAt(pos);
            if(c == COLOR_CHAR)
            {
                pos++;
                if(pos < l)
                {
                    int index = s.charAt(pos);
                    if(index >= 0 && index <= colors.length)
                    {
                        color = colors[s.charAt(pos)];
                    }
                }
                continue;
            }
            else if(c == '\n')
            {
                y += FONT_SIZE + LINE_STEP;
                x = oldX;
                continue;
            }

            addRectangle(x, y, c);
            x += FONT_SIZE;
        }
        return y + FONT_SIZE + LINE_STEP;
    }
    
    public Rectangle getSize(String s)
    {
        int length = 0;
        int counter = 0;
        for(int i = 0; i < s.length(); i++)
        {
            switch(s.charAt(i))
            {
                case '\n':
                    counter++;
                    break;
                case COLOR_CHAR:
                    i++;
                    break;
                default:
                    length++;
            }
        }
        return new Rectangle(FONT_SIZE * length, (FONT_SIZE + LINE_STEP) * counter);
    }
    
    public Rectangle getSize(int w, int h)
    {
        return new Rectangle(FONT_SIZE * w, (FONT_SIZE + LINE_STEP) * h);
    }
    
    public float getHeight()
    {
        return FONT_SIZE + LINE_STEP;
    }
}