add fx module: screen fade, flash, shake and tone

1 files changed, 75 insertions, 0 deletions

diff --git a/kon/konfx.h b/kon/konfx.h
new file mode 100644
index 0000000..0261b59
--- /dev/null
+++ b/kon/konfx.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * konfx.h
+ *
+ * Copyright (c) 2026 KonAki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef KONFX_H
+#define KONFX_H
+
+#include "konsofren.h"
+#include "kon2d.h"
+
+/*** definition ***/
+
+/* the effects that go over a whole picture: a fade to a colour, a flash, a shake and a tone. they are done to the pixels after
+   the scene is drawn, so they work on anything, a map, a stage, a 3D view. start them with the functions below, call kon_screenfxUpdate
+   every frame and then kon_screenfxApply on the framebuffer when the scene is drawn. keep the struct around, it holds the state */
+typedef struct kon_screenfx {
+	kon_tween_t fade;
+	uint32_t fadeColor;
+	kon_tween_t flash;
+	uint32_t flashColor;
+	kon_tween_t tone[4]; /* red, green, blue, gray */
+	float shakeX, shakeY, shakeHz, shakeTime, shakeDuration;
+} kon_screenfx_t;
+
+void kon_screenfxInit(kon_screenfx_t *fx);
+
+/* fades to color (alpha is ignored) until it covers alpha of the picture, 1 is all of it, 0 is back to normal */
+void kon_screenfxFade(kon_screenfx_t *fx, uint32_t color, float alpha, float seconds, kon_ease_t ease);
+
+/* covers the picture with color at the strength of its alpha and lets it go in seconds */
+void kon_screenfxFlash(kon_screenfx_t *fx, uint32_t color, float seconds);
+
+/* shakes by up to powerX and powerY pixels, hz times a second, getting weaker until it stops after seconds */
+void kon_screenfxShake(kon_screenfx_t *fx, float powerX, float powerY, float hz, float seconds);
+
+/* r, g, b from -255 to 255 are added to every pixel, gray from 0 to 255 takes the colour out, 255 is black and white.
+   all zero is no change. the same as RPG Maker's screen tone */
+void kon_screenfxTone(kon_screenfx_t *fx, int r, int g, int b, int gray, float seconds, kon_ease_t ease);
+
+void kon_screenfxUpdate(kon_screenfx_t *fx, float dt);
+
+/* 1 while something is still changing, for a script that waits for it */
+int kon_screenfxBusy(const kon_screenfx_t *fx);
+
+/* how far the picture is shifted right now, for a game that would rather move its camera than the pixels */
+void kon_screenfxOffset(const kon_screenfx_t *fx, int *x, int *y);
+
+/* tone and shake, then flash and fade. two halves so a text box can be drawn between them and stay still and clear,
+   kon_screenfxApply is both for when it should all be covered */
+void kon_screenfxApplyScene(const kon_screenfx_t *fx, kon_framebuffer_t *fb);
+void kon_screenfxApplyOverlay(const kon_screenfx_t *fx, kon_framebuffer_t *fb);
+void kon_screenfxApply(const kon_screenfx_t *fx, kon_framebuffer_t *fb);
+
+#endif