diff --git a/tutorial/04_texture.lolfx b/tutorial/04_texture.lolfx index 8c91fe26..48987db0 100644 --- a/tutorial/04_texture.lolfx +++ b/tutorial/04_texture.lolfx @@ -74,3 +74,71 @@ void main(void) gl_FragColor = vec4(mix(p.x, 1.0, lum), lum, lum, 1.0); } +[vert.hlsl] + +void main(float2 in_Position : POSITION, + out float4 out_Position : POSITION, + out float4 pass_Position : TEXCOORD0) +{ + pass_Position = float4(0.5 * in_Position + 0.5, 0.0, 1.0); + out_Position = float4(in_Position, 0.5, 1.0); +} + +[frag.hlsl] + +float segdist(float2 p1, float2 p2, float2 a) +{ + float d = max(1e-10, dot(p2 - p1, p2 - p1)); + float t = clamp(dot(a - p1, p2 - p1) / d, 0.0, 1.0); + return distance(a, lerp(p1, p2, t)); +} + +void main(in float4 pass_Position : TEXCOORD0, + uniform sampler2D u_Texture, + out float4 out_FragColor : COLOR) +{ + float width = 800.0; + float height = 600.0; + float texture_width = 256.0; + float line_width = 1.2; + float dot_size = 1.0; + float4 delta = float4(1.0 / texture_width, 0.0, + 2.0 / texture_width, 0.0); + + float2 p = pass_Position.xy; + float2 tc = float2(floor(p.x * texture_width) / texture_width, p.y); + float t = p.x * texture_width - floor(p.x * texture_width); + float4 c; + c[0] = tex2D(u_Texture, tc - delta.xy).x; + c[1] = tex2D(u_Texture, tc).x; + c[2] = tex2D(u_Texture, tc + delta.xy).x; + c[3] = tex2D(u_Texture, tc + delta.zw).x; + + /* Find the 4 closest points in screen space */ + float2 p0 = float2((tc.x - delta.x) * width, c[0] * height); + float2 p1 = float2((tc.x ) * width, c[1] * height); + float2 p2 = float2((tc.x + delta.x) * width, c[2] * height); + float2 p3 = float2((tc.x + delta.z) * width, c[3] * height); + float2 a = float2(p.x * width, p.y * height); + + /* Compute distance to segments */ + float d = segdist(p0, p1, a); + d = min(d, segdist(p1, p2, a)); + d = min(d, segdist(p2, p3, a)); + + /* Compute distance to dots */ + d = min(d, length(a - p0) - dot_size); + d = min(d, length(a - p1) - dot_size); + d = min(d, length(a - p2) - dot_size); + d = min(d, length(a - p3) - dot_size); + + /* Add line width */ + float lum = clamp(line_width - d, 0.0, 1.0); + + /* Compensate for sRGB */ + lum = pow(1.0 - lum, 1.0 / 2.4); + + /* Choose some funny colours */ + out_FragColor = float4(lerp(p.x, 1.0, lum), lum, lum, 1.0); +} +