more clouds

src/net/torvald/terrarum/weather/WeatherObjectCloud.kt

@@ -0,0 +1,52 @@
+package net.torvald.terrarum.weather
+
+import com.badlogic.gdx.graphics.g2d.SpriteBatch
+import com.badlogic.gdx.graphics.g2d.TextureRegion
+import com.badlogic.gdx.math.Vector2
+import com.badlogic.gdx.math.Vector3
+import kotlin.math.sign
+
+/**
+ * Created by minjaesong on 2023-08-21.
+ */
+class WeatherObjectCloud(private val texture: TextureRegion) : WeatherObject() {
+
+    /**
+     * To actually utilise this value, your render code must begin the spritebatch per-object, like so:
+     * ```
+     * batch.shader = cloudShader
+     * for (it in clouds) {
+     *     batch.begin()
+     *     batch.shader.setUniformf("gamma", it.darkness)
+     *     batch.draw(it, ...)
+     *     batch.end()
+     * }
+     */
+    var darkness: Vector2 = Vector2(0.5f, 2.0f) // the "gamma" value fed into the clouds shader
+
+    override fun update() {
+    }
+
+    /**
+     * FlowVector: In which direction the cloud flows. Vec3(dX, dY, dScale)
+     * Resulting vector: (x + dX, y + dY, scale * dScale)
+     */
+    fun update(flowVector: Vector3, gait: Float) {
+        posX += flowVector.x * gait * scale * scale
+        posY += flowVector.y * gait * scale * scale
+        scale *= flowVector.z
+    }
+
+    /**
+     * X/Y position is a bottom-centre point of the image
+     * Shader must be prepared prior to the render() call
+     */
+    override fun render(batch: SpriteBatch, offsetX: Float, offsetY: Float) {
+        val x = posX + offsetX - texture.regionWidth * scale * 0.5f
+        val y = posY + offsetY - texture.regionHeight * scale
+
+        batch.draw(texture, x, y, texture.regionWidth * scale, texture.regionHeight * scale)
+    }
+
+    override fun dispose() { /* cloud texture will be disposed of by the WeatherMixer */ }
+}