1coin_shaders(3)                      Coin                      coin_shaders(3)
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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       • coin_two_sided_lighting - Set to 1 for two-sided, 0 for normal
46       Example scene graph that renders per-fragment OpenGL Phong lighting for
47       one light source. The shaders assume the first light source is a
48       directional light. This is the case if you open the file in a standard
49       examiner viewer.
50       The iv-file:
51       Separator {
52         ShaderProgram {
53           shaderObject [
54             VertexShader {
55               sourceProgram "perpixel_vertex.glsl"
56             }
57             FragmentShader {
58               sourceProgram "perpixel_fragment.glsl"
59             }
60           ]
61         }
62         Complexity { value 1.0 }
63         Material { diffuseColor 1 0 0 specularColor 1 1 1 shininess 0.9 }
64         Sphere { }
65
66         Translation { translation 3 0 0 }
67         Material { diffuseColor 0 1 0 specularColor 1 1 1 shininess 0.9 }
68         Cone { }
69
70         Translation { translation 3 0 0 }
71         Material { diffuseColor 0.8 0.4 0.1 specularColor 1 1 1 shininess 0.9 }
72         Cylinder { }
73       }
74
75       The vertex shader (perpixel_vertex.glsl):
76       varying vec3 ecPosition3;
77       varying vec3 fragmentNormal;
78
79       void main(void)
80       {
81         vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
82         ecPosition3 = ecPosition.xyz / ecPosition.w;
83         fragmentNormal = normalize(gl_NormalMatrix * gl_Normal);
84
85         gl_Position = ftransform();
86         gl_FrontColor = gl_Color;
87       }
88
89       The fragment shader (perpixel_fragment.glsl):
90       varying vec3 ecPosition3;
91       varying vec3 fragmentNormal;
92
93       void DirectionalLight(in int i,
94                             in vec3 normal,
95                             inout vec4 ambient,
96                             inout vec4 diffuse,
97                             inout vec4 specular)
98       {
99         float nDotVP; // normal . light direction
100         float nDotHV; // normal . light half vector
101         float pf;     // power factor
102
103         nDotVP = max(0.0, dot(normal, normalize(vec3(gl_LightSource[i].position))));
104         nDotHV = max(0.0, dot(normal, vec3(gl_LightSource[i].halfVector)));
105
106         if (nDotVP == 0.0)
107           pf = 0.0;
108         else
109           pf = pow(nDotHV, gl_FrontMaterial.shininess);
110
111         ambient += gl_LightSource[i].ambient;
112         diffuse += gl_LightSource[i].diffuse * nDotVP;
113         specular += gl_LightSource[i].specular * pf;
114       }
115
116       void main(void)
117       {
118         vec3 eye = -normalize(ecPosition3);
119         vec4 ambient = vec4(0.0);
120         vec4 diffuse = vec4(0.0);
121         vec4 specular = vec4(0.0);
122         vec3 color;
123
124         DirectionalLight(0, normalize(fragmentNormal), ambient, diffuse, specular);
125
126         color =
127           gl_FrontLightModelProduct.sceneColor.rgb +
128           ambient.rgb * gl_FrontMaterial.ambient.rgb +
129           diffuse.rgb * gl_Color.rgb +
130           specular.rgb * gl_FrontMaterial.specular.rgb;
131
132         gl_FragColor = vec4(color, gl_Color.a);
133       }
134
135Version 4.0.0                   Wed Jan 19 2022                coin_shaders(3)