minetest/client/shaders/shadow_shaders/pass1_vertex.glsl

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uniform mat4 LightMVP; // world matrix
uniform vec4 CameraPos; // camera position
varying vec4 tPos;
uniform float xyPerspectiveBias0;
uniform float xyPerspectiveBias1;
uniform float zPerspectiveBias;
vec4 getRelativePosition(in vec4 position)
{
vec2 l = position.xy - CameraPos.xy;
vec2 s = l / abs(l);
s = (1.0 - s * CameraPos.xy);
l /= s;
return vec4(l, s);
}
float getPerspectiveFactor(in vec4 relativePosition)
{
float pDistance = length(relativePosition.xy);
float pFactor = pDistance * xyPerspectiveBias0 + xyPerspectiveBias1;
return pFactor;
}
vec4 applyPerspectiveDistortion(in vec4 position)
{
vec4 l = getRelativePosition(position);
float pFactor = getPerspectiveFactor(l);
l.xy /= pFactor;
position.xy = l.xy * l.zw + CameraPos.xy;
position.z *= zPerspectiveBias;
return position;
}
void main()
{
vec4 pos = LightMVP * gl_Vertex;
tPos = applyPerspectiveDistortion(pos);
gl_Position = vec4(tPos.xyz, 1.0);
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
}