[Interest] Where is "shininess" in these shaders?

[Tom O'Reilly]

I have little experience with OpenGL shader programs - can someone please help me understand some GLSL shader code? 

I have source code for Qt 5.14.2, including DataVisualization, and would like to modify the source to reduce specular “shininess” from Surface3D. [ https://drive.google.com/file/d/1Sx8d8guY1T13EkRaql5WVlMfowe1ai3j/view?usp=sharing | This screenshot ] shows a Surface3D that depicts topography, and it has a very “shiny” look to it. Debugging with gdb I’ve determined that the following shaders are generating this surface. Could someone please comment on how this shader code affects the shininess of the surface? The code doesn't look like it's directly based on the [ https://en.wikibooks.org/wiki/GLSL_Programming/GLUT/Specular_Highlights | Phong reflection model, ] e.g. I don't see an exponential "shininess" term in the code. 

Thanks very much! 

vertex shader (“shadow.vert”) 

#version 120 


uniform highp mat4 MVP; 

uniform highp mat4 V; 

uniform highp mat4 M; 

uniform highp mat4 itM; 

uniform highp mat4 depthMVP; 

uniform highp vec3 lightPosition_wrld; 


attribute highp vec3 vertexPosition_mdl; 

attribute highp vec3 vertexNormal_mdl; 

attribute highp vec2 vertexUV; 


varying highp vec2 UV; 

varying highp vec3 position_wrld; 

varying highp vec3 normal_cmr; 

varying highp vec3 eyeDirection_cmr; 

varying highp vec3 lightDirection_cmr; 

varying highp vec4 shadowCoord; 

varying highp vec2 coords_mdl; 


const highp mat4 bias = mat4(0.5, 0.0, 0.0, 0.0, 

0.0, 0.5, 0.0, 0.0, 

0.0, 0.0, 0.5, 0.0, 

0.5, 0.5, 0.5, 1.0); 


void main() { 

gl_Position = MVP * vec4(vertexPosition_mdl, 1.0); 

coords_mdl = vertexPosition_mdl.xy; 

shadowCoord = bias * depthMVP * vec4(vertexPosition_mdl, 1.0); 

position_wrld = vec4(M * vec4(vertexPosition_mdl, 1.0)).xyz; 

vec3 vertexPosition_cmr = vec4(V * M * vec4(vertexPosition_mdl, 1.0)).xyz; 

eyeDirection_cmr = vec3(0.0, 0.0, 0.0) - vertexPosition_cmr; 

lightDirection_cmr = vec4(V * vec4(lightPosition_wrld, 0.0)).xyz; 

normal_cmr = vec4(V * itM * vec4(vertexNormal_mdl, 0.0)).xyz; 

UV = vertexUV; 

} 





fragment shader (“surfaceShadowNoTex.frag”): 

#version 120 


varying highp vec2 coords_mdl; 

varying highp vec3 position_wrld; 

varying highp vec3 normal_cmr; 

varying highp vec3 eyeDirection_cmr; 

varying highp vec3 lightDirection_cmr; 

varying highp vec4 shadowCoord; 


uniform highp sampler2DShadow shadowMap; 

uniform sampler2D textureSampler; 

uniform highp vec3 lightPosition_wrld; 

uniform highp float lightStrength; 

uniform highp float ambientStrength; 

uniform highp float shadowQuality; 

uniform highp vec4 lightColor; 

uniform highp float gradMin; 

uniform highp float gradHeight; 


highp vec2 poissonDisk[16] = vec2[16](vec2(-0.94201624, -0.39906216), 

vec2(0.94558609, -0.76890725), 

vec2(-0.094184101, -0.92938870), 

vec2(0.34495938, 0.29387760), 

vec2(-0.91588581, 0.45771432), 

vec2(-0.81544232, -0.87912464), 

vec2(-0.38277543, 0.27676845), 

vec2(0.97484398, 0.75648379), 

vec2(0.44323325, -0.97511554), 

vec2(0.53742981, -0.47373420), 

vec2(-0.26496911, -0.41893023), 

vec2(0.79197514, 0.19090188), 

vec2(-0.24188840, 0.99706507), 

vec2(-0.81409955, 0.91437590), 

vec2(0.19984126, 0.78641367), 

vec2(0.14383161, -0.14100790)); 


void main() { 

highp vec2 gradientUV = vec2(0.0, gradMin + coords_mdl.y * gradHeight); 

highp vec3 materialDiffuseColor = texture2D(textureSampler, gradientUV).xyz; 

highp vec3 materialAmbientColor = lightColor.rgb * ambientStrength * 

materialDiffuseColor; 


highp vec3 materialSpecularColor = lightColor.rgb; 


highp vec3 n = normalize(normal_cmr); 

highp vec3 l = normalize(lightDirection_cmr); 

highp float cosTheta = clamp(dot(n, l), 0.0, 1.0); 


highp vec3 E = normalize(eyeDirection_cmr); 

highp vec3 R = reflect(-l, n); 

highp float cosAlpha = clamp(dot(E, R), 0.0, 1.0); 


highp float bias = 0.005 * tan(acos(cosTheta)); 

bias = clamp(bias, 0.001, 0.01); 


vec4 shadCoords = shadowCoord; 

shadCoords.z -= bias; 


highp float visibility = 0.6; 

for (int i = 0; i < 15; i++) { 

vec4 shadCoordsPD = shadCoords; 

shadCoordsPD.x += cos(poissonDisk[i].x) / shadowQuality; 

shadCoordsPD.y += sin(poissonDisk[i].y) / shadowQuality; 

visibility += 0.025 * shadow2DProj(shadowMap, shadCoordsPD).r; 

} 


gl_FragColor.rgb = 

(materialAmbientColor + 

materialDiffuseColor * lightStrength * cosTheta + 

materialSpecularColor * lightStrength * pow(cosAlpha, 10)); 

gl_FragColor.a = 1.0; 

gl_FragColor.rgb = visibility * clamp(gl_FragColor.rgb, 0.0, 1.0); 

} 

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