1coin_shaders(3)                      Coin                      coin_shaders(3)
2
3
4

NAME

6       coin_shaders - Shaders in Coin Coin 2.5 added support for shaders. The
7       main nodes used are SoShaderProgram, SoVertexShader, SoFragmentShader,
8       and SoGeometryShader. A typical scene graph with shaders will look
9       something like this:
10
11       Separator {
12         ShaderProgram {
13           shaderObject [
14             VertexShader {
15               sourceProgram "myvertexshader.glsl"
16               parameter [
17                 ShaderParameter1f { name "myvertexparam" value 1.0 }
18               ]
19             }
20             FragmentShader {
21               sourceProgram "myfragmentshader.glsl"
22               parameter [
23                 ShaderParameter1f { name "myfragmentparam" value 2.0 }
24               ]
25             }
26           ]
27         }
28         Cube { }
29       }
30
31       This will render the Cube with the vertex and fragment shaders
32       specified in myvertexshader.glsl and myfragmentshader.glsl. Coin also
33       supports ARB shaders and Cg shaders (if the Cg library is installed).
34       However, we recommend using GLSL since we will focus mostly on support
35       this shader language.
36
37       Coin defines some named parameters that can be added by the application
38       programmer, and which will be automatically updated by Coin while
39       traversing the scene graph.
40
41       • coin_texunit[n]_model - Set to 0 when texturing is disabled, and to
42         SoTextureImageElement::Model if there's a current texture on the
43         state for unit n.
44       • coin_light_model - Set to 1 for PHONG, 0 for BASE_COLOR lighting.
45       Example scene graph that renders per-fragment OpenGL Phong lighting for
46       one light source. The shaders assume the first light source is a
47       directional light. This is the case if you open the file in a standard
48       examiner viewer.
49       The iv-file:
50       Separator {
51         ShaderProgram {
52           shaderObject [
53             VertexShader {
54               sourceProgram "perpixel_vertex.glsl"
55             }
56             FragmentShader {
57               sourceProgram "perpixel_fragment.glsl"
58             }
59           ]
60         }
61         Complexity { value 1.0 }
62         Material { diffuseColor 1 0 0 specularColor 1 1 1 shininess 0.9 }
63         Sphere { }
64
65         Translation { translation 3 0 0 }
66         Material { diffuseColor 0 1 0 specularColor 1 1 1 shininess 0.9 }
67         Cone { }
68
69         Translation { translation 3 0 0 }
70         Material { diffuseColor 0.8 0.4 0.1 specularColor 1 1 1 shininess 0.9 }
71         Cylinder { }
72       }
73
74       The vertex shader (perpixel_vertex.glsl):
75       varying vec3 ecPosition3;
76       varying vec3 fragmentNormal;
77
78       void main(void)
79       {
80         vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
81         ecPosition3 = ecPosition.xyz / ecPosition.w;
82         fragmentNormal = normalize(gl_NormalMatrix * gl_Normal);
83
84         gl_Position = ftransform();
85         gl_FrontColor = gl_Color;
86       }
87
88       The fragment shader (perpixel_vertex.glsl):
89       varying vec3 ecPosition3;
90       varying vec3 fragmentNormal;
91
92       void DirectionalLight(in int i,
93                             in vec3 normal,
94                             inout vec4 ambient,
95                             inout vec4 diffuse,
96                             inout vec4 specular)
97       {
98         float nDotVP; // normal . light direction
99         float nDotHV; // normal . light half vector
100         float pf;     // power factor
101
102         nDotVP = max(0.0, dot(normal, normalize(vec3(gl_LightSource[i].position))));
103         nDotHV = max(0.0, dot(normal, vec3(gl_LightSource[i].halfVector)));
104
105         if (nDotVP == 0.0)
106           pf = 0.0;
107         else
108           pf = pow(nDotHV, gl_FrontMaterial.shininess);
109
110         ambient += gl_LightSource[i].ambient;
111         diffuse += gl_LightSource[i].diffuse * nDotVP;
112         specular += gl_LightSource[i].specular * pf;
113       }
114
115       void main(void)
116       {
117         vec3 eye = -normalize(ecPosition3);
118         vec4 ambient = vec4(0.0);
119         vec4 diffuse = vec4(0.0);
120         vec4 specular = vec4(0.0);
121         vec3 color;
122
123         DirectionalLight(0, normalize(fragmentNormal), ambient, diffuse, specular);
124
125         color =
126           gl_FrontLightModelProduct.sceneColor.rgb +
127           ambient.rgb * gl_FrontMaterial.ambient.rgb +
128           diffuse.rgb * gl_Color.rgb +
129           specular.rgb * gl_FrontMaterial.specular.rgb;
130
131         gl_FragColor = vec4(color, gl_Color.a);
132       }
133
134Version 2.5.0                   Wed Jan 19 2022                coin_shaders(3)