Vertex Shaders - Praise for OpenGL ES 30 Programming Guide - page 209

Example 8-6 Vertex Skinning Shader with No Check of Whether

Matrix Weight = 0 (continued)

void skin_position ( in vec4 position, float m_wt, int m_indx,
out vec4 skinned_position )
{
vec4 tmp;
tmp.x = dot ( position, matrix_palette[m_indx] );
tmp.y = dot ( position, matrix_palette[m_indx + c_one] );
tmp.z = dot ( position, matrix_palette[m_indx + c_two] );
tmp.w = position.w;

skinned_position += m_wt * tmp;
}
void skin_normal ( in vec3 normal, float m_wt, int m_indx,
inout vec3 skinned_normal )
{
vec3 tmp;
tmp.x = dot ( normal, matrix_palette[m_indx].xyz );
tmp.y = dot ( normal, matrix_palette[m_indx + c_one].xyz );
tmp.z = dot ( normal, matrix_palette[m_indx + c_two].xyz );

skinned_normal += m_wt * tmp;
}

void do_skinning ( in vec4 position, in vec3 normal,
out vec4 skinned_position,
out vec3 skinned_normal )
{
skinned_position = vec4 ( float ( c_zero ) );
skinned_normal = vec3 ( float ( c_zero ) );

// transform position and normal to eye space using matrix
// palette with four matrices used to transform a vertex

float m_wt = a_matrixweights[0];
int m_indx = int ( a_matrixindices[0] ) * c_three;
skin_position ( position, m_wt, m_indx, skinned_position );
skin_normal ( normal, m_wt, m_indx, skinned_normal );

m_wt = a_matrixweights[1] ;
m_indx = int ( a_matrixindices[1] ) * c_three;
skin_position ( position, m_wt, m_indx, skinned_position );
skin_normal ( normal, m_wt, m_indx, skinned_normal );

m_wt = a_matrixweights[2];
m_indx = int ( a_matrixindices[2] ) * c_three;
skin_position ( position, m_wt, m_indx, skinned_position );
skin_normal ( normal, m_wt, m_indx, skinned_normal );

(continues)