1coin_shaders(3)                      Coin                      coin_shaders(3)
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NAME

6       coin_shaders - Shaders in Coin
7
8       Coin 2.5 added support for shaders. The main nodes used are
9       SoShaderProgram, SoVertexShader, SoFragmentShader, and
10       SoGeometryShader. A typical scene graph with shaders will look
11       something like this:
12
13       Separator {
14         ShaderProgram {
15           shaderObject [
16             VertexShader {
17               sourceProgram "myvertexshader.glsl"
18               parameter [
19                 ShaderParameter1f { name "myvertexparam" value 1.0 }
20               ]
21             }
22             FragmentShader {
23               sourceProgram "myfragmentshader.glsl"
24               parameter [
25                 ShaderParameter1f { name "myfragmentparam" value 2.0 }
26               ]
27             }
28           ]
29         }
30         Cube { }
31       }
32
33       This will render the Cube with the vertex and fragment shaders
34       specified in myvertexshader.glsl and myfragmentshader.glsl. Coin also
35       supports ARB shaders and Cg shaders (if the Cg library is installed).
36       However, we recommend using GLSL since we will focus mostly on support
37       this shader language.
38
39       Coin defines some named parameters that can be added by the application
40       programmer, and which will be automatically updated by Coin while
41       traversing the scene graph.
42
43       • coin_texunit[n]_model - Set to 0 when texturing is disabled, and to
44         SoTextureImageElement::Model if there's a current texture on the
45         state for unit n.
46       • coin_light_model - Set to 1 for PHONG, 0 for BASE_COLOR lighting.
47       Example scene graph that renders per-fragment OpenGL Phong lighting for
48       one light source. The shaders assume the first light source is a
49       directional light. This is the case if you open the file in a standard
50       examiner viewer.
51       The iv-file:
52       Separator {
53         ShaderProgram {
54           shaderObject [
55             VertexShader {
56               sourceProgram "perpixel_vertex.glsl"
57             }
58             FragmentShader {
59               sourceProgram "perpixel_fragment.glsl"
60             }
61           ]
62         }
63         Complexity { value 1.0 }
64         Material { diffuseColor 1 0 0 specularColor 1 1 1 shininess 0.9 }
65         Sphere { }
66
67         Translation { translation 3 0 0 }
68         Material { diffuseColor 0 1 0 specularColor 1 1 1 shininess 0.9 }
69         Cone { }
70
71         Translation { translation 3 0 0 }
72         Material { diffuseColor 0.8 0.4 0.1 specularColor 1 1 1 shininess 0.9 }
73         Cylinder { }
74       }
75
76       The vertex shader (perpixel_vertex.glsl):
77       varying vec3 ecPosition3;
78       varying vec3 fragmentNormal;
79
80       void main(void)
81       {
82         vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
83         ecPosition3 = ecPosition.xyz / ecPosition.w;
84         fragmentNormal = normalize(gl_NormalMatrix * gl_Normal);
85
86         gl_Position = ftransform();
87         gl_FrontColor = gl_Color;
88       }
89
90       The fragment shader (perpixel_vertex.glsl):
91       varying vec3 ecPosition3;
92       varying vec3 fragmentNormal;
93
94       void DirectionalLight(in int i,
95                             in vec3 normal,
96                             inout vec4 ambient,
97                             inout vec4 diffuse,
98                             inout vec4 specular)
99       {
100         float nDotVP; // normal . light direction
101         float nDotHV; // normal . light half vector
102         float pf;     // power factor
103
104         nDotVP = max(0.0, dot(normal, normalize(vec3(gl_LightSource[i].position))));
105         nDotHV = max(0.0, dot(normal, vec3(gl_LightSource[i].halfVector)));
106
107         if (nDotVP == 0.0)
108           pf = 0.0;
109         else
110           pf = pow(nDotHV, gl_FrontMaterial.shininess);
111
112         ambient += gl_LightSource[i].ambient;
113         diffuse += gl_LightSource[i].diffuse * nDotVP;
114         specular += gl_LightSource[i].specular * pf;
115       }
116
117       void main(void)
118       {
119         vec3 eye = -normalize(ecPosition3);
120         vec4 ambient = vec4(0.0);
121         vec4 diffuse = vec4(0.0);
122         vec4 specular = vec4(0.0);
123         vec3 color;
124
125         DirectionalLight(0, normalize(fragmentNormal), ambient, diffuse, specular);
126
127         color =
128           gl_FrontLightModelProduct.sceneColor.rgb +
129           ambient.rgb * gl_FrontMaterial.ambient.rgb +
130           diffuse.rgb * gl_Color.rgb +
131           specular.rgb * gl_FrontMaterial.specular.rgb;
132
133         gl_FragColor = vec4(color, gl_Color.a);
134       }
135
136Version 2.5.0                   Wed Jan 18 2023                coin_shaders(3)