Use webgl

src/Julia.kt

@@ -0,0 +1,140 @@
+import com.persesgames.shader.ShaderProgram
+import com.persesgames.shader.VertextAttributeInfo
+import org.khronos.webgl.Float32Array
+import org.khronos.webgl.WebGLBuffer
+import org.khronos.webgl.WebGLRenderingContext
+import kotlin.browser.window
+
+/**
+ * User: rnentjes
+ * Date: 21-5-16
+ * Time: 17:06
+ */
+
+private val vertexShader = """
+    attribute vec2 a_position;
+
+    uniform vec4 u_viewWindow;
+
+    varying vec2 v_coord;
+
+    void main(void) {
+        v_coord = a_position * u_viewWindow.zw + u_viewWindow.xy;
+
+        gl_Position = vec4(a_position, 0.0, 1.0);
+    }
+"""
+
+private val fragmentShader = """
+    precision mediump float;
+
+    uniform vec2 u_julia;
+    uniform float u_iteratorOffset;
+
+    varying vec2 v_coord;
+
+    void main(void) {
+        float xx = v_coord.x;
+        float yy = v_coord.y;
+        float xt = 0.0;
+
+        gl_FragColor = vec4( 0.0, 0.0, 0.0, 1.0);
+
+        for (int iteration = 0; iteration < 1000; iteration++) {
+            if (xx*xx + yy*yy > 4.0) {
+              float mu = u_iteratorOffset + float(iteration) + 1.0 - log(log(xx*xx + yy*yy)) / log(2.0);
+
+              float it = mod(mu * 7.0, 768.0);
+
+              float red = min(it, 255.0) / 255.0;
+              float green = max(0.0, min(it, 511.0) - 256.0) / 255.0;
+              float blue = max(0.0, min(it, 767.0) - 512.0) / 255.0;
+
+              gl_FragColor = vec4( red, green, blue, 1.0);
+              break;
+            }
+            xt = xx*xx - yy*yy + u_julia.x;
+            yy = 2.0*xx*yy + u_julia.y;
+            xx = xt;
+        }
+    }
+"""
+
+class JuliaData {
+    var juliaX: Float = 0f
+    var juliaY: Float = 0f
+
+    var offsetX: Float = 0f
+    var offsetY: Float = 0f
+    var scaleX: Float = 1f
+    var scaleY: Float = 1f
+
+    var iteratorOffset: Float = 0f
+}
+
+class Julia(val html: HTMLElements) {
+    val webgl = html.webgl
+    val shaderProgram: ShaderProgram<JuliaData>
+    val data: JuliaData = JuliaData()
+    val attribBuffer: WebGLBuffer
+    val vertices: Float32Array
+    val start = Date().getTime() - 20000
+
+    init {
+        val array: Array<Float> = arrayOf(
+          -1f,-1f,
+           1f,-1f,
+           1f, 1f,
+           1f, 1f,
+          -1f, 1f,
+          -1f,-1f
+        )
+
+        vertices = Float32Array(array.size)
+        vertices.set(array, 0)
+
+        val setter = { program: ShaderProgram<JuliaData>, data: JuliaData ->
+            program.setUniform2f("u_julia", data.juliaX, data.juliaY)
+            program.setUniform4f("u_viewWindow", data.offsetX, data.offsetY, data.scaleX, data.scaleY)
+            program.setUniform1f("u_iteratorOffset", data.iteratorOffset)
+        }
+
+        val vainfo = arrayOf(
+          VertextAttributeInfo("a_position", 2)
+        )
+
+        shaderProgram = ShaderProgram(webgl, WebGLRenderingContext.TRIANGLES, vertexShader, fragmentShader, vainfo, setter)
+
+
+        attribBuffer = webgl.createBuffer() ?: throw IllegalStateException("Unable to create webgl buffer!")
+        webgl.bindBuffer(WebGLRenderingContext.ARRAY_BUFFER, attribBuffer);
+    }
+
+    fun render() {
+        html.resize()
+
+        webgl.clearColor(1f, 1f, 1f, 1f)
+        webgl.clear(WebGLRenderingContext.COLOR_BUFFER_BIT)
+
+        var time = (start - (Date().getTime())) / 1000.0
+
+        data.juliaX = -0.391f + (Math.sin(time / 31) / 10f).toFloat()
+        data.juliaY = -0.587f + (Math.cos(time / 23.07) / 10f).toFloat()
+
+        data.scaleX = 1.3f - Math.sin(time / 10.0).toFloat() * 0.9f
+        data.scaleY = 1.3f - Math.sin(time / 10.0).toFloat() * 0.9f
+
+        data.iteratorOffset = 0f //time.toFloat() * 10f
+
+        shaderProgram.begin(attribBuffer, data)
+
+        webgl.bufferData(WebGLRenderingContext.ARRAY_BUFFER, vertices, WebGLRenderingContext.DYNAMIC_DRAW);
+        webgl.drawArrays(shaderProgram.drawType, 0, 6)
+
+        shaderProgram.end()
+
+        window.requestAnimationFrame {
+            render()
+        }
+    }
+}