48 lines
1.3 KiB
Plaintext
48 lines
1.3 KiB
Plaintext
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/* simple.glsl
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simple diffuse lighting based on laberts cosine law; see e.g.:
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http://en.wikipedia.org/wiki/Lambertian_reflectance
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http://en.wikipedia.org/wiki/Lambert%27s_cosine_law
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*/
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---VERTEX SHADER-------------------------------------------------------
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#ifdef GL_ES
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precision highp float;
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#endif
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attribute vec3 v_pos;
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attribute vec3 v_normal;
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uniform mat4 modelview_mat;
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uniform mat4 projection_mat;
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varying vec4 normal_vec;
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varying vec4 vertex_pos;
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void main (void) {
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//compute vertex position in eye_space and normalize normal vector
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vec4 pos = modelview_mat * vec4(v_pos,1.0);
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vertex_pos = pos;
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normal_vec = vec4(v_normal,0.0);
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gl_Position = projection_mat * pos;
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}
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---FRAGMENT SHADER-----------------------------------------------------
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#ifdef GL_ES
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precision highp float;
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#endif
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varying vec4 normal_vec;
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varying vec4 vertex_pos;
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uniform mat4 normal_mat;
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void main (void){
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//correct normal, and compute light vector (assume light at the eye)
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vec4 v_normal = normalize( normal_mat * normal_vec ) ;
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vec4 v_light = normalize( vec4(0,0,0,1) - vertex_pos );
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//reflectance based on lamberts law of cosine
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float theta = clamp(dot(v_normal, v_light), 0.0, 1.0);
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gl_FragColor = vec4(theta, theta, theta, 1.0);
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}
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