$input v_color0
$input v_normal
$input v_uv0
$input v_wpos

#include "common.sh"

SAMPLER2D(s_texColor, 0);
uniform vec4 u_time;
uniform vec4 u_testColor;

float circle(vec2 uv, float radius)
{
	float distSq = uv.x * uv.x + uv.y * uv.y;
	float result = sqrt(distSq) / radius;
	// return result < 0.5;
	return clamp(1.0 - result, 0.0, 1.0);
}

float calcBrightness(vec3 lightPos, vec3 vertPos, vec3 normal)
{
	vec3 lightDir = normalize(lightPos - vertPos);
	float diffuse = max(0.0, dot(lightDir, normal));
	return diffuse * clamp(1.0 - distance(lightPos, vertPos) * 0.01, 0.0, 1.0);
}

float circles(vec2 uv, float level, float subLevel, float brightness)
{
	vec2 offsetUv = uv + 0.5;
	vec2 baseUv = (offsetUv % 1.0) - 0.5;
	vec2 step1Uv = ((offsetUv + vec2(0.5, 0.5)) % 1.0) - 0.5;
	vec2 step2Uv = ((offsetUv + vec2(0.5, 0.0)) % 1.0) - 0.5;
	vec2 step3Uv = ((offsetUv + vec2(0.0, 0.5)) % 1.0) - 0.5;

	float step = subLevel * 3.0;
	float step1 = clamp(step, 0.0, 1.0);
	float step2 = clamp(step - 1, 0.0, 1.0);
	float step3 = clamp(step - 2, 0.0, 1.0);
	
	float sum = 0.0;
	sum = circle(baseUv, lerp(0.5, 0.25, subLevel) * brightness);
	sum = max(sum, circle(step1Uv, 0.25 * step1 * brightness));
	sum = max(sum, circle(step2Uv, 0.25 * step2 * brightness));
	sum = max(sum, circle(step3Uv, 0.25 * step3 * brightness));

	return min(sum, 1.0);
}

vec3 desaturate(vec3 color)
{
	return vec3_splat(dot(color, vec3(0.33, 0.34, 0.33)));
}

void main()
{
	float testRadius = 30.0;
	float testSpeed = 1.0;
	vec3 testOffset = vec3(0.0, 0.0, 50.0);
	float3 lightPos = vec3(sin(u_time.x * testSpeed) * testRadius, 5.0, cos(u_time.x * testSpeed) * testRadius);
	float brightness = calcBrightness(lightPos, v_wpos, v_normal);
	// brightness = 0.1 + brightness * 0.9;
	
	float baseScale = 2.0;
	float2 dx = ddx(v_uv0 * baseScale);
	float2 dy = ddy(v_uv0 * baseScale);
	float2x2 mat = float2x2(dx, dy);
	float4 vectorized = float4(dx, dy);
	float qq = dot(vectorized, vectorized);
	float rr = determinant(mat);
	float discriminantSqr = max(0.0, qq*qq - 4.0*rr*rr);
	float discriminant = sqrt(discriminantSqr);	
	float2 freq = sqrt(float2(qq + discriminant, qq - discriminant) / 2.0);

	float spacing = freq.y * exp2(2.0);
	spacing = 1.0 / spacing;
	spacing *= brightness; // TODO: check reference to see how to calculate this!
	float spacingLog = max(log2(spacing), 0.0);
	int patternScaleLevel = floor(spacingLog);
	float patternFractional = spacingLog - patternScaleLevel;
	
	vec2 uv = v_uv0 * exp2(patternScaleLevel);
	float dither = circles(uv, patternScaleLevel, patternFractional, brightness);
	vec3 color = desaturate(u_testColor.xyz) * 0.01 + dither * u_testColor.xyz * 0.95;
	vec3 smoothColor = brightness * u_testColor.xyz;
	vec3 mixedColor = 0.1 * smoothColor + 0.9 * color;
	gl_FragColor = vec4(mixedColor, 1.0);
	// gl_FragColor = brightness;
	// gl_FragColor = dither;
	// gl_FragColor = u_testColor;
	gl_FragColor = texture2D(s_texColor, v_uv0);
}