feat: Add dev capes

src/main/resources/assets/firmament/shaders/cape/parallax.fsh

@@ -0,0 +1,53 @@
+#version 150
+
+#moj_import <minecraft:fog.glsl>
+#define M_PI 3.1415926535897932384626433832795
+#define M_TAU (2.0 * M_PI)
+uniform sampler2D Sampler0;
+uniform sampler2D Sampler1;
+uniform sampler2D Sampler3;
+
+uniform vec4 ColorModulator;
+uniform float FogStart;
+uniform float FogEnd;
+uniform vec4 FogColor;
+uniform float Animation;
+
+in float vertexDistance;
+in vec4 vertexColor;
+in vec4 lightMapColor;
+in vec4 overlayColor;
+in vec2 texCoord0;
+
+out vec4 fragColor;
+
+float highlightDistance(vec2 coord, vec2 direction, float time) {
+	vec2 dir = normalize(direction);
+	float projection = dot(coord, dir);
+	float animationTime =  sin(projection + time * 13 * M_TAU);
+	if (animationTime < 0.997) {
+		return 0.0;
+	}
+	return animationTime;
+}
+
+void main() {
+	vec4 color = texture(Sampler0, texCoord0);
+	if (color.g > 0.99) {
+		// TODO: maybe this speed in each direction should be a uniform
+		color = texture(Sampler1, texCoord0 + Animation * vec2(3.0, -2.0));
+	}
+
+	vec4 highlightColor = texture(Sampler3, texCoord0);
+	if (highlightColor.a > 0.5) {
+		color = highlightColor;
+		float animationHighlight = highlightDistance(texCoord0, vec2(-12.0, 2.0), Animation);
+		color.rgb += (animationHighlight);
+	}
+	#ifdef ALPHA_CUTOUT
+	if (color.a < ALPHA_CUTOUT) {
+		discard;
+	}
+	#endif
+	fragColor = linear_fog(color, vertexDistance, FogStart, FogEnd, FogColor);
+}

src/main/resources/assets/firmament/textures/cape/REUSE.toml

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+#SPDX-FileCopyrightText: 2025 Linnea Gräf <nea@nea.moe>
+#
+#SPDX-License-Identifier: CC0-1.0
+version = 1
+
+[[annotations]]
+path = ["firmament_star.png", "parallax_background.png", "parallax_template.png"]
+SPDX-License-Identifier = "CC-BY-4.0"
+SPDX-FileCopyrightText = ["ic22487", "Linnea Gräf"]
+
+[[annotations]]
+path = ["firm_static.png"]
+SPDX-License-Identifier = "CC-BY-4.0"
+SPDX-FileCopyrightText = ["ic22487", "kathund"]
+
+