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IECoreGL::CurvesPrimitive : Interpolate vertex color correctly
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@danieldresser
danieldresser committed Mar 31, 2020
1 parent f17f17d commit 723ef16
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104 changes: 45 additions & 59 deletions glsl/IECoreGL/CurvesPrimitive.h
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Original file line number Diff line number Diff line change
Expand Up @@ -70,73 +70,62 @@
\
IECOREGL_CURVESPRIMITIVE_DECLARE_VERTEX_PASS_THROUGH_PARAMETERS

#define IECOREGL_CURVESPRIMITIVE_COEFFICIENTS( t, c0, c1, c2, c3 ) \
ieCurvesPrimitiveCoefficients(\
basis, t, c0, c1, c2, c3\
)
#define IECOREGL_CURVESPRIMITIVE_COEFFICIENTS( t ) \
ieCurvesPrimitiveCoefficients( basis, t )

#define IECOREGL_CURVESPRIMITIVE_POSITION( t )\
ieCurvesPrimitivePosition( basis, t )
#define IECOREGL_CURVESPRIMITIVE_DERIVATIVE_COEFFICIENTS( t ) \
ieCurvesPrimitiveDerivativeCoefficients( basis, t )

#define IECOREGL_CURVESPRIMITIVE_POSITION( coeffs )\
ieCurvesPrimitivePosition( coeffs )

#define IECOREGL_CURVESPRIMITIVE_LINEARFRAME( i, p, normal, uTangent, vTangent ) \
ieCurvesPrimitiveLinearFrame( i, p, normal, uTangent, vTangent )

#define IECOREGL_CURVESPRIMITIVE_CUBICFRAME( t, p, normal, uTangent, vTangent ) \
ieCurvesPrimitiveCubicFrame( basis, t, p, normal, uTangent, vTangent )
#define IECOREGL_CURVESPRIMITIVE_CUBICFRAME( coeffs, derivCoeffs, p, normal, uTangent, vTangent ) \
ieCurvesPrimitiveCubicFrame( coeffs, derivCoeffs, p, normal, uTangent, vTangent )

# define IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_LINEAR( i )\
fragmentCs = geometryCs[i+1];

# define IECOREGL_ASSIGN_VERTEX_PASS_THROUGH \
fragmentCs = geometryCs[1];
# define IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_CUBIC( coeffs )\
fragmentCs = coeffs[0] * geometryCs[0] + coeffs[1] * geometryCs[1] + coeffs[2] * geometryCs[2] + coeffs[3] * geometryCs[3];

void ieCurvesPrimitiveCoefficients( in mat4x4 basis, in float t, out float c0, out float c1, out float c2, out float c3 )
vec4 ieCurvesPrimitiveCoefficients( in mat4x4 basis, in float t )
{
float t2 = t * t;
float t3 = t2 * t;

c0 = basis[0][0] * t3 + basis[1][0] * t2 + basis[2][0] * t + basis[3][0];
c1 = basis[0][1] * t3 + basis[1][1] * t2 + basis[2][1] * t + basis[3][1];
c2 = basis[0][2] * t3 + basis[1][2] * t2 + basis[2][2] * t + basis[3][2];
c3 = basis[0][3] * t3 + basis[1][3] * t2 + basis[2][3] * t + basis[3][3];
return vec4(
basis[0][0] * t3 + basis[1][0] * t2 + basis[2][0] * t + basis[3][0],
basis[0][1] * t3 + basis[1][1] * t2 + basis[2][1] * t + basis[3][1],
basis[0][2] * t3 + basis[1][2] * t2 + basis[2][2] * t + basis[3][2],
basis[0][3] * t3 + basis[1][3] * t2 + basis[2][3] * t + basis[3][3]
);
}

// As above but also computes d0-d3, the coefficients for computing tangents.
void ieCurvesPrimitiveCoefficients(
in mat4x4 basis, in float t,
out float c0, out float c1, out float c2, out float c3,
out float d0, out float d1, out float d2, out float d3
)
// As above but instead computes the coefficients for computing tangents.
vec4 ieCurvesPrimitiveDerivativeCoefficients( in mat4x4 basis, in float t )
{
float t2 = t * t;
float t3 = t2 * t;

c0 = basis[0][0] * t3 + basis[1][0] * t2 + basis[2][0] * t + basis[3][0];
c1 = basis[0][1] * t3 + basis[1][1] * t2 + basis[2][1] * t + basis[3][1];
c2 = basis[0][2] * t3 + basis[1][2] * t2 + basis[2][2] * t + basis[3][2];
c3 = basis[0][3] * t3 + basis[1][3] * t2 + basis[2][3] * t + basis[3][3];

float twoT = 2.0 * t;
float threeT2 = 3.0 * t2;

d0 = basis[0][0] * threeT2 + basis[1][0] * twoT + basis[2][0];
d1 = basis[0][1] * threeT2 + basis[1][1] * twoT + basis[2][1];
d2 = basis[0][2] * threeT2 + basis[1][2] * twoT + basis[2][2];
d3 = basis[0][3] * threeT2 + basis[1][3] * twoT + basis[2][3];
float threeT2 = 3.0 * t * t;

return vec4(
basis[0][0] * threeT2 + basis[1][0] * twoT + basis[2][0],
basis[0][1] * threeT2 + basis[1][1] * twoT + basis[2][1],
basis[0][2] * threeT2 + basis[1][2] * twoT + basis[2][2],
basis[0][3] * threeT2 + basis[1][3] * twoT + basis[2][3]
);
}

vec4 ieCurvesPrimitivePosition( in float c0, in float c1, in float c2, in float c3 )
vec4 ieCurvesPrimitivePosition( in vec4 coeffs )
{
return

gl_in[0].gl_Position * c0 +
gl_in[1].gl_Position * c1 +
gl_in[2].gl_Position * c2 +
gl_in[3].gl_Position * c3;
}

vec4 ieCurvesPrimitivePosition( in mat4x4 basis, in float t )
{
float c0, c1, c2, c3;
ieCurvesPrimitiveCoefficients( basis, t, c0, c1, c2, c3 );
return ieCurvesPrimitivePosition( c0, c1, c2, c3 );
gl_in[0].gl_Position * coeffs[0] +
gl_in[1].gl_Position * coeffs[1] +
gl_in[2].gl_Position * coeffs[2] +
gl_in[3].gl_Position * coeffs[3];
}

void ieCurvesPrimitiveUTangentAndNormal( in vec4 p, in vec4 vTangent, out vec4 uTangent, out vec4 normal )
Expand Down Expand Up @@ -175,27 +164,24 @@ void ieCurvesPrimitiveLinearFrame(
}

void ieCurvesPrimitiveCubicFrame(
in mat4x4 basis, in float t,
in vec4 coeffs, in vec4 derivCoeffs,
out vec4 p, out vec4 n,
out vec4 uTangent, out vec4 vTangent
)
{
float c0, c1, c2, c3, d0, d1, d2, d3;
ieCurvesPrimitiveCoefficients( basis, t, c0, c1, c2, c3, d0, d1, d2, d3 );

p =

gl_in[0].gl_Position * c0 +
gl_in[1].gl_Position * c1 +
gl_in[2].gl_Position * c2 +
gl_in[3].gl_Position * c3;
gl_in[0].gl_Position * coeffs[0] +
gl_in[1].gl_Position * coeffs[1] +
gl_in[2].gl_Position * coeffs[2] +
gl_in[3].gl_Position * coeffs[3];

vTangent =

gl_in[0].gl_Position * d0 +
gl_in[1].gl_Position * d1 +
gl_in[2].gl_Position * d2 +
gl_in[3].gl_Position * d3;
gl_in[0].gl_Position * derivCoeffs[0] +
gl_in[1].gl_Position * derivCoeffs[1] +
gl_in[2].gl_Position * derivCoeffs[2] +
gl_in[3].gl_Position * derivCoeffs[3];

vTangent = normalize( vTangent );

Expand Down
17 changes: 10 additions & 7 deletions src/IECoreGL/CurvesPrimitive.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -287,8 +287,9 @@ const std::string &CurvesPrimitive::cubicLinesGeometrySource()
" for( int i = 0; i < 10; i++ )"
" {"
" float t = float( i ) / 9.0;"
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH"
" gl_Position = IECOREGL_CURVESPRIMITIVE_POSITION( t );"
" vec4 coeffs = IECOREGL_CURVESPRIMITIVE_COEFFICIENTS( t );"
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_CUBIC( coeffs );"
" gl_Position = IECOREGL_CURVESPRIMITIVE_POSITION( coeffs );"
" EmitVertex();"
""
" }"
Expand Down Expand Up @@ -318,17 +319,19 @@ const std::string &CurvesPrimitive::cubicRibbonsGeometrySource()
" {"
""
" float t = float( i ) / 9.0;"
" vec4 coeffs = IECOREGL_CURVESPRIMITIVE_COEFFICIENTS( t );"
" vec4 derivCoeffs = IECOREGL_CURVESPRIMITIVE_DERIVATIVE_COEFFICIENTS( t );"
" vec4 p, n, uTangent, vTangent;"
" IECOREGL_CURVESPRIMITIVE_CUBICFRAME( t, p, n, uTangent, vTangent );"
" IECOREGL_CURVESPRIMITIVE_CUBICFRAME( coeffs, derivCoeffs, p, n, uTangent, vTangent );"
""
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH"
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_CUBIC( coeffs )"
" fragmentN = n.xyz;"
" fragmentI = -n.xyz;"
" fragmentuv = vec2( 0, t );"
" gl_Position = p + width * uTangent;"
" EmitVertex();"
""
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH"
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_CUBIC( coeffs )"
" fragmentN = n.xyz;"
" fragmentI = -n.xyz;"
" fragmentuv = vec2( 1, t );"
Expand Down Expand Up @@ -363,13 +366,13 @@ const std::string &CurvesPrimitive::linearRibbonsGeometrySource()
" vec4 p, n, uTangent, vTangent;"
" IECOREGL_CURVESPRIMITIVE_LINEARFRAME( i, p, n, uTangent, vTangent );"

" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH"
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_LINEAR( i )"
" fragmentN = n.xyz;"
" fragmentI = -n.xyz;"
" gl_Position = p + width * uTangent;"
" EmitVertex();"

" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH"
" IECOREGL_ASSIGN_VERTEX_PASS_THROUGH_LINEAR( i )"
" fragmentN = n.xyz;"
" fragmentI = -n.xyz;"
" gl_Position = p - width * uTangent;"
Expand Down

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