76 lines
2.3 KiB
GLSL
76 lines
2.3 KiB
GLSL
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//
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// Fragment shader for procedurally generated toy ball
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//
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// Author: Bill Licea-Kane
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//
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// Copyright (c) 2002-2003 ATI Research
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//
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// See ATI-License.txt for license information
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//
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varying vec4 ECposition; // surface position in eye coordinates
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varying vec4 ECballCenter; // ball center in eye coordinates
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uniform vec4 LightDir; // light direction, should be normalized
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uniform vec4 HVector; // reflection vector for infinite light source
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uniform vec4 SpecularColor;
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uniform vec4 Red, Yellow, Blue;
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uniform vec4 HalfSpace0; // half-spaces used to define star pattern
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uniform vec4 HalfSpace1;
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uniform vec4 HalfSpace2;
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uniform vec4 HalfSpace3;
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uniform vec4 HalfSpace4;
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uniform float InOrOutInit; // = -3
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uniform float StripeWidth; // = 0.3
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uniform float FWidth; // = 0.005
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void main()
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{
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vec4 normal; // Analytically computed normal
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vec4 p; // Point in shader space
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vec4 surfColor; // Computed color of the surface
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float intensity; // Computed light intensity
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vec4 distance; // Computed distance values
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float inorout; // Counter for computing star pattern
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p.xyz = normalize(ECposition.xyz - ECballCenter.xyz); // Calculate p
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p.w = 1.0;
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inorout = InOrOutInit; // initialize inorout to -3
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distance[0] = dot(p, HalfSpace0);
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distance[1] = dot(p, HalfSpace1);
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distance[2] = dot(p, HalfSpace2);
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distance[3] = dot(p, HalfSpace3);
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distance = smoothstep(-FWidth, FWidth, distance);
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inorout += dot(distance, vec4(1.0));
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distance.x = dot(p, HalfSpace4);
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distance.y = StripeWidth - abs(p.z);
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distance = smoothstep(-FWidth, FWidth, distance);
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inorout += distance.x;
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inorout = clamp(inorout, 0.0, 1.0);
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surfColor = mix(Yellow, Red, inorout);
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surfColor = mix(surfColor, Blue, distance.y);
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// normal = point on surface for sphere at (0,0,0)
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normal = p;
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// Per fragment diffuse lighting
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intensity = 0.2; // ambient
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intensity += 0.8 * clamp(dot(LightDir, normal), 0.0, 1.0);
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surfColor *= intensity;
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// Per fragment specular lighting
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intensity = clamp(dot(HVector, normal), 0.0, 1.0);
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intensity = pow(intensity, SpecularColor.a);
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surfColor += SpecularColor * intensity;
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gl_FragColor = surfColor;
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}
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