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

#include "common.sh"

SAMPLER2D(s_texColor, 0);
SAMPLER3D(s_ditherSampler, 1);
uniform vec4 u_time;
uniform vec4 u_testColor;

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 calcBrightnessDirectional(vec3 sunDir, vec3 normal)
{
	return max(0.0, dot(sunDir, normal));
}

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);
	float brightness = calcBrightnessDirectional(vec3(0.5, 0.3, 1.0), v_normal);
	brightness = 1.0;
	// brightness = sin(u_time.x) * 0.5 + 0.5;
	
	// Magic dot frequency calculation
	float baseScale = 8.0;
	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);

	// Figuring out how many dots we want
	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 dotsTotal = 4;
	float subLayer = lerp(0.25 * dotsTotal, dotsTotal, patternFractional);
	subLayer = (subLayer - 0.5) / dotsTotal;
	
	vec4 circleSample = texture3D(s_ditherSampler, vec3(uv, subLayer));	
	float circleVal = circleSample.x < 0.75 ? 0.1 : 0.9;
	
	// Coloring
	vec3 texColor = u_testColor.x > 0.1 ? u_testColor.xyz : texture2D(s_texColor, v_uv0).xyz;
	vec3 finalColor = texColor * vec3(circleVal, circleVal, circleVal);
	gl_FragColor = vec4(finalColor, 1.0);
}