想問關於glsl 的 reliefmap
他的tangent space 的 tangent 要怎麼給值
// object space eye position
uniform vec3 eye_pos;
// object space light position
uniform vec3 light_pos;
attribute vec4 tangent;!!!!!!!!!!!!!!!!!!!!!! 這邊的值 在 opengl
裡面要怎麼給???? 誰可以幫幫我>_<
// tangent space vector to the light
varying vec3 to_light;
//tangent space vector to the eye
varying vec3 to_eye;
// fragment position in tangent space
varying vec3 position_tan;
// eye space vector to fragment. used for depth correct.
varying vec3 eye_to_pos;
void main()
{
vec3 bitangent = cross(gl_Normal, tangent.xyz) * tangent.w;
mat3 TBN = mat3(tangent.xyz, bitangent, gl_Normal);
// TBN transforms from tangent to object space so post multiply
// to transform by its "inverse" since we need to go from object
// to tangent space.
to_light = (light_pos - vec3(gl_Vertex)) * TBN;
to_eye = (eye_pos - vec3(gl_Vertex)) * TBN;
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
position_tan = vec3(gl_Vertex) * TBN;
eye_to_pos = vec3(gl_ModelViewMatrix * gl_Vertex);
}
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