wtf with the premultiplying i didn't even told it to do so

FontTestGDX/src/FontTestGDX.kt

@@ -1,11 +1,15 @@
 import com.badlogic.gdx.*
 import com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application
 import com.badlogic.gdx.backends.lwjgl3.Lwjgl3ApplicationConfiguration
+import com.badlogic.gdx.files.FileHandle
 import com.badlogic.gdx.graphics.*
 import com.badlogic.gdx.graphics.g2d.SpriteBatch
 import com.badlogic.gdx.graphics.glutils.FrameBuffer
 import com.badlogic.gdx.utils.ScreenUtils
+import com.badlogic.gdx.utils.StreamUtils
 import net.torvald.terrarumsansbitmap.gdx.GameFontBase
+import java.io.IOException
+import java.io.OutputStream
 
 /**
  * Created by minjaesong on 2018-07-26.
@@ -28,7 +32,7 @@ class FontTestGDX : Game() {
     private val outimageName = if (testing) "testing.PNG" else "demo.PNG"
 
     override fun create() {
-        font = GameFontBase("./assets", flipY = false, errorOnUnknownChar = false) // must test for two flipY cases
+        font = GameFontBase("./assets", flipY = false, errorOnUnknownChar = false, shadowAlpha = 0.796f) // must test for two flipY cases
 
         val inTextFile = Gdx.files.internal("./$demotextName")
         val reader = inTextFile.reader("UTF-8")
@@ -72,16 +76,19 @@ class FontTestGDX : Game() {
         if (tex == null) {
             frameBuffer.begin()
 
-            Gdx.gl.glClearColor(.141f, .141f, .141f, 1f)
+            Gdx.gl.glClearColor(0f,0f,0f,0f)
             Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)
             Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
             Gdx.gl.glEnable(GL20.GL_BLEND)
-            Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA)
+            Gdx.gl.glBlendFuncSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_ONE, GL20.GL_ONE)
+//            Gdx.gl.glBlendFuncSeparate(GL20.GL_SRC_COLOR, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_SRC_ALPHA, GL20.GL_ONE)
+
+//            Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA)
 
             batch.projectionMatrix = camera.combined
             batch.begin()
 
-            batch.color = Color(0xeeeeeeff.toInt())
+            batch.color = Color(-1)
             inputText.forEachIndexed { index, s ->
                 font.draw(batch, s, 10f, TEXH - 30f - index * font.lineHeight)
             }
@@ -94,6 +101,7 @@ class FontTestGDX : Game() {
                 val pixmap = ScreenUtils.getFrameBufferPixmap(0, 0, frameBuffer.width, frameBuffer.height)
 
                 PixmapIO.writePNG(Gdx.files.local(outimageName), pixmap)
+//                writeTGA(Gdx.files.local(outimageName), pixmap, false)
                 pixmap.dispose()
 
                 screenshotExported = true
@@ -107,6 +115,14 @@ class FontTestGDX : Game() {
             tex = frameBuffer.colorBufferTexture
         }
 
+
+        Gdx.gl.glClearColor(.141f, .141f, .141f, 1f)
+        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT)
+        Gdx.gl.glEnable(GL20.GL_TEXTURE_2D)
+        Gdx.gl.glEnable(GL20.GL_BLEND)
+        Gdx.gl.glBlendFuncSeparate(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA, GL20.GL_ONE, GL20.GL_ONE)
+
+
         batch.begin()
         batch.color = Color.WHITE
         batch.draw(tex, 0f, (TEXH.toFloat()/HEIGHT)*TEXH - scrollOffsetY, TEXW.toFloat(), -(TEXH.toFloat() / HEIGHT) * TEXH.toFloat())
@@ -155,6 +171,91 @@ class FontTestGDX : Game() {
             return true
         }
     }
+
+
+    @Throws(IOException::class)
+    private fun writeTGA(file: FileHandle, pixmap: Pixmap, flipY: Boolean) {
+        val output = file.write(false)
+        try {
+            _writeTGA(output, pixmap, true, flipY)
+        } finally {
+            StreamUtils.closeQuietly(output)
+        }
+    }
+
+    @Throws(IOException::class)
+    private fun _writeTGA(out: OutputStream, pixmap: Pixmap, verbatim: Boolean, flipY: Boolean) {
+        val width: ByteArray =  toShortLittle(pixmap.width)
+        val height: ByteArray = toShortLittle(pixmap.height)
+        val zero: ByteArray =   toShortLittle(0)
+        out.write(0) // ID field: empty
+        out.write(0) // no colour map, but should be ignored anyway as it being unmapped RGB
+        out.write(2) // 2 means unmapped RGB
+        out.write(byteArrayOf(0, 0, 0, 0, 0)) // color map spec: empty
+        out.write(zero) // x origin: 0
+        out.write(zero) // y origin: 0
+        out.write(width) // width
+        out.write(height) // height
+        out.write(32) // image pixel size: we're writing 32-bit image (8bpp BGRA)
+        out.write(8) // image descriptor: dunno, Photoshop writes 8 in there
+
+        // write actual image data
+        // since we're following Photoshop's conventional header, we also follows Photoshop's
+        // TGA saving scheme, that is:
+        //     1. BGRA order
+        //     2. Y-Flipped but not X-Flipped
+        if (!flipY) {
+            for (y in pixmap.height - 1 downTo 0) {
+                for (x in 0 until pixmap.width) {
+                    writeTga(x, y, verbatim, pixmap, out)
+                }
+            }
+        } else {
+            for (y in 0 until pixmap.height) {
+                for (x in 0 until pixmap.width) {
+                    writeTga(x, y, verbatim, pixmap, out)
+                }
+            }
+        }
+
+
+        // write footer
+        // 00 00 00 00 00 00 00 00 TRUEVISION-XFILE 2E 00
+        out.write(byteArrayOf(0, 0, 0, 0, 0, 0, 0, 0))
+        if (verbatim) out.write("TRUEVISION-XFILE".toByteArray()) else out.write("TerrarumHappyTGA".toByteArray())
+        out.write(byteArrayOf(0x2E, 0))
+        out.flush()
+        out.close()
+    }
+
+    private val zeroalpha = byteArrayOf(0, 0, 0, 0)
+    @Throws(IOException::class)
+    private fun writeTga(x: Int, y: Int, verbatim: Boolean, pixmap: Pixmap, out: OutputStream) {
+        val color = pixmap.getPixel(x, y)
+
+        // if alpha == 0, write special value instead
+        if (verbatim && color and 0xFF == 0) {
+            out.write(zeroalpha)
+        } else {
+            out.write(RGBAtoBGRA(color))
+        }
+    }
+
+    private fun toShortLittle(i: Int): ByteArray {
+        return byteArrayOf(
+            (i and 0xFF).toByte(),
+            (i ushr 8 and 0xFF).toByte()
+        )
+    }
+
+    private fun RGBAtoBGRA(rgba: Int): ByteArray {
+        return byteArrayOf(
+            (rgba ushr 8 and 0xFF).toByte(),
+            (rgba ushr 16 and 0xFF).toByte(),
+            (rgba ushr 24 and 0xFF).toByte(),
+            (rgba and 0xFF).toByte()
+        )
+    }
 }
 
 lateinit var appConfig: Lwjgl3ApplicationConfiguration