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path: root/src/shader/code/vertex.glsl
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static const std::string VERTEX_SHADER_CODE = R"(
#version 430

layout (location=0) in vec3 VertexPosition;

out VS_OUT {
	vec3 color;
} vs_out;

uniform uint nX;
uniform uint nY;

const float displayAmplifier = 5.0;

float unit(float x) {
	return 1.0/(1.0+exp(-x));
}

float sq(float x) {
	return x*x;
}

float norm(vec2 v) {
	return sqrt(sq(v.x)+sq(v.y));
}

vec3 getColor(float x) {
	return x*vec3(1.0,0.0,0.0) + (1-x)*vec3(-0.5,0.0,1.0);
}

vec2 fluidVertexAtIndex(uint i) {
	const float y = floor(float(i) / float(nX));
	return vec2(
		i - nX*y,
		y
	);

}

void main() {
	const vec2 idx = fluidVertexAtIndex(gl_VertexID);

	gl_Position  = vec4(
		idx.x - nX/2,
		idx.y - nY/2,
		0.,
		1.
	);

	vs_out.color = getColor(unit(displayAmplifier * VertexPosition.z * norm(VertexPosition.xy)));
}
)";