From 6c2692fb634783e6cdd39c0fb8c00973a78650ee Mon Sep 17 00:00:00 2001
From: Ricardo Matias <ricardo.matias0@gmail.com>
Date: Tue, 7 Jan 2020 13:29:40 +0100
Subject: [PATCH] Add Bloom effect

---
 orx-fx/src/main/kotlin/color/Bloom.kt         | 79 +++++++++++++++++++
 .../openrndr/extra/fx/gl3/color/bloom.frag    | 20 +++++
 2 files changed, 99 insertions(+)
 create mode 100644 orx-fx/src/main/kotlin/color/Bloom.kt
 create mode 100644 orx-fx/src/main/resources/org/openrndr/extra/fx/gl3/color/bloom.frag

diff --git a/orx-fx/src/main/kotlin/color/Bloom.kt b/orx-fx/src/main/kotlin/color/Bloom.kt
new file mode 100644
index 00000000..fc5e89ed
--- /dev/null
+++ b/orx-fx/src/main/kotlin/color/Bloom.kt
@@ -0,0 +1,79 @@
+package org.openrndr.extra.fx.color
+
+import org.openrndr.draw.*
+import org.openrndr.extra.fx.blend.Add
+import org.openrndr.extra.fx.blur.ApproximateGaussianBlur
+import org.openrndr.extra.fx.filterFragmentCode
+
+
+class Bloom(blur: Filter = ApproximateGaussianBlur()) : Filter(Shader.createFromCode(filterVertexCode, filterFragmentCode("color/bloom.frag"))) {
+    /**
+     * the blur filter to use for the bloom, default is Approximate Gaussian Blur
+     */
+    var blur: Filter = blur
+
+    /**
+     * number of downsampled textures to use, default value is 2
+     */
+    var downsamples: Int = 2
+
+    /**
+     * rate of downsampling, f.ex: 4 -> 4x, 8x, 16x.., default value is 2
+     */
+    var downsampleRate: Int = 2
+
+    /**
+     * blending amount between original image and blurred, default value is 0.5
+     */
+    var blendFactor: Double by parameters
+
+    /**
+     * brightness of the resulting image, default value is 0.5
+     */
+    var brightness: Double by parameters
+
+    init {
+        blendFactor = 0.5
+        brightness = 0.5
+    }
+
+    private val samplers: MutableList<Pair<ColorBuffer, ColorBuffer>> = mutableListOf()
+    private var lastDownsampleRate = 0
+
+    private val blendAdd = Add()
+
+    override fun apply(source: Array<ColorBuffer>, target: Array<ColorBuffer>) {
+        val src = source[0]
+        val dest = target[0]
+
+        if (samplers.isEmpty() || samplers.size != downsamples || lastDownsampleRate != downsampleRate) {
+            samplers.clear()
+
+            lastDownsampleRate = downsampleRate
+
+            for (downsample in 0 until downsamples * 2 step 2) {
+                val bufferA = colorBuffer(dest.width, dest.height, 1.0 / (downsample + downsampleRate), target[0].format, ColorType.FLOAT16)
+                val bufferB = colorBuffer(dest.width, dest.height, 1.0 / (downsample + downsampleRate), target[0].format, ColorType.FLOAT16)
+
+                samplers.add(Pair(bufferA, bufferB))
+            }
+        }
+
+        for ((bufferA) in samplers) {
+            blur.apply(src, bufferA)
+        }
+
+        for ((index, buffers) in samplers.asReversed().withIndex()) {
+            val (bufferCurrA) = buffers
+
+            if (index + 1 <= samplers.lastIndex) {
+                val (bufferNextA, bufferNextB) = samplers.asReversed()[index + 1]
+
+                blur.apply(bufferCurrA, bufferNextB)
+                blendAdd.apply(arrayOf(bufferNextA, bufferNextB), bufferNextA)
+            } else {
+                super.apply(arrayOf(src, bufferCurrA), target)
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/orx-fx/src/main/resources/org/openrndr/extra/fx/gl3/color/bloom.frag b/orx-fx/src/main/resources/org/openrndr/extra/fx/gl3/color/bloom.frag
new file mode 100644
index 00000000..720523d9
--- /dev/null
+++ b/orx-fx/src/main/resources/org/openrndr/extra/fx/gl3/color/bloom.frag
@@ -0,0 +1,20 @@
+#version 330
+
+in vec2 v_texCoord0;
+out vec4 o_color;
+
+uniform sampler2D tex0;
+uniform sampler2D tex1;
+uniform float blendFactor;
+uniform float brightness;
+
+void main() {
+    vec3 original = texture(tex0, v_texCoord0).rgb;
+    vec3 bloom = texture(tex1, v_texCoord0).rgb;
+
+    vec3 hdrColor = mix(original, bloom, blendFactor);
+
+    vec3 result = vec3(1.0) - exp(-hdrColor * brightness);
+
+    o_color = vec4(result, 1.0);
+}