Implement animated flash tiles in Tilemap

Flash tiles start with an alpha of 60, which ramps up to 120
in 16 frames and 4 steps, then ramps down again over the same period.

mkxp.pro

@@ -96,6 +96,7 @@ EMBED = shader/transSimple.frag \
         shader/simple.frag \
         shader/simpleColor.frag \
         shader/simpleAlpha.frag \
+        shader/flashMap.frag \
         shader/simple.vert \
         shader/simpleColor.vert \
         shader/sprite.vert \

shader/flashMap.frag

@@ -0,0 +1,13 @@
+
+uniform float alpha;
+
+varying vec4 v_color;
+
+void main()
+{
+	vec4 frag = vec4(0, 0, 0, 1);
+
+	frag.rgb = mix(vec3(0, 0, 0), v_color.rgb, alpha);
+
+	gl_FragColor = frag;
+}

src/globalstate.cpp

@@ -71,6 +71,7 @@ struct GlobalStatePrivate
 	SimpleSpriteShader simpleSpriteShader;
 	SpriteShader spriteShader;
 	PlaneShader planeShader;
+	FlashMapShader flashMapShader;
 	TransShader transShader;
 	SimpleTransShader sTransShader;
 	HueShader hueShader;
@@ -187,6 +188,7 @@ GSATT(SimpleAlphaShader&, simpleAlphaShader)
 GSATT(SimpleSpriteShader&, simpleSpriteShader)
 GSATT(SpriteShader&, spriteShader)
 GSATT(PlaneShader&, planeShader)
+GSATT(FlashMapShader&, flashMapShader)
 GSATT(TransShader&, transShader)
 GSATT(SimpleTransShader&, sTransShader)
 GSATT(HueShader&, hueShader)

src/globalstate.h

@@ -48,6 +48,7 @@ class SimpleAlphaShader;
 class SimpleSpriteShader;
 class SpriteShader;
 class PlaneShader;
+class FlashMapShader;
 class TransShader;
 class SimpleTransShader;
 class HueShader;
@@ -87,6 +88,7 @@ struct GlobalState
 	SimpleSpriteShader &simpleSpriteShader();
 	SpriteShader &spriteShader();
 	PlaneShader &planeShader();
+	FlashMapShader &flashMapShader();
 	TransShader &transShader();
 	SimpleTransShader &sTransShader();
 	HueShader &hueShader();

src/shader.cpp

@@ -36,6 +36,7 @@
 #include "../simple.frag.xxd"
 #include "../simpleColor.frag.xxd"
 #include "../simpleAlpha.frag.xxd"
+#include "../flashMap.frag.xxd"
 #include "../simple.vert.xxd"
 #include "../simpleColor.vert.xxd"
 #include "../sprite.vert.xxd"
@@ -369,6 +370,21 @@ void PlaneShader::setOpacity(float value)
 }
 
 
+FlashMapShader::FlashMapShader()
+{
+	INIT_SHADER(simpleColor, flashMap);
+
+	ShaderBase::init();
+
+	GET_U(alpha);
+}
+
+void FlashMapShader::setAlpha(float value)
+{
+	glUniform1f(u_alpha, value);
+}
+
+
 HueShader::HueShader()
 {
 	INIT_SHADER(simple, hue);

src/shader.h

@@ -176,6 +176,17 @@ private:
 	GLint u_tone, u_color, u_flash, u_opacity;
 };
 
+class FlashMapShader : public ShaderBase
+{
+public:
+	FlashMapShader();
+
+	void setAlpha(float value);
+
+private:
+	GLint u_alpha;
+};
+
 class HueShader : public ShaderBase
 {
 public:

src/tilemap.cpp

@@ -144,6 +144,18 @@ static const Position positions[] =
 
 static elementsN(positions);
 
+static const uint8_t flashAlpha[] =
+{
+	/* Fade in */
+	0x3C, 0x3C, 0x3C, 0x3C, 0x4B, 0x4B, 0x4B, 0x4B,
+	0x5A, 0x5A, 0x5A, 0x5A, 0x69, 0x69, 0x69, 0x69,
+	/* Fade out */
+	0x78, 0x78, 0x78, 0x78, 0x69, 0x69, 0x69, 0x69,
+	0x5A, 0x5A, 0x5A, 0x5A, 0x4B, 0x4B, 0x4B, 0x4B
+};
+
+static elementsN(flashAlpha);
+
 struct GroundLayer : public ViewportElement
 {
 	GLsizei vboCount;
@@ -233,6 +245,7 @@ struct TilemapPrivate
 		VAO::ID vao;
 		VBO::ID vbo;
 		int quadCount;
+		uint8_t alphaIdx;
 	} flash;
 
 	/* Scene elements */
@@ -319,6 +332,7 @@ struct TilemapPrivate
 		flash.vbo = VBO::gen();
 		flash.vao = VAO::gen();
 		flash.quadCount = 0;
+		flash.alphaIdx = 0;
 
 		VAO::bind(flash.vao);
 
@@ -751,12 +765,11 @@ struct TilemapPrivate
 		if (packed == 0)
 			return false;
 
-		const float max = 60.0 / 255.0;
+		const float max = 0xF;
-		const float step = max / 0xF;
 
-		float b = ((packed & 0x000F) >> 0) * step;
+		float b = ((packed & 0x000F) >> 0) / max;
-		float g = ((packed & 0x00F0) >> 4) * step;
+		float g = ((packed & 0x00F0) >> 4) / max;
-		float r = ((packed & 0x0F00) >> 8) * step;
+		float r = ((packed & 0x0F00) >> 8) / max;
 
 		out = Vec4(r, g, b, 1);
 
@@ -923,9 +936,10 @@ void GroundLayer::draw()
 		glState.blendMode.pushSet(BlendAddition);
 		glState.texture2D.pushSet(false);
 
-		SimpleColorShader &shader = gState->simpleColorShader();
+		FlashMapShader &shader = gState->flashMapShader();
 		shader.bind();
 		shader.applyViewportProj();
+		shader.setAlpha(flashAlpha[p->flash.alphaIdx] / 255.f);
 
 		for (int i = 0; i < positionsN; ++i)
 		{
@@ -1062,6 +1076,11 @@ static const uchar atAnimation[16*4] =
 
 void Tilemap::update()
 {
+	/* Animate flash */
+	if (++p->flash.alphaIdx > flashAlphaN-1)
+		p->flash.alphaIdx = 0;
+
+	/* Animate autotiles */
 	if (!p->atlas.animated)
 		return;