int shDrawRadialGradientMesh(SHPaint *p, SHVector2 *min, SHVector2 *max,
VGPaintMode mode, GLenum texUnit)
{
SHint i, j;
float a, n;
SHfloat cx = p->radialGradient[0];
SHfloat cy = p->radialGradient[1];
SHfloat fx = p->radialGradient[2];
SHfloat fy = p->radialGradient[3];
float r = p->radialGradient[4];
float fcx, fcy, rr, C;
SHVector2 ux;
SHVector2 uy;
SHVector2 c, f;
SHVector2 cf;
SHMatrix3x3 *m;
SHMatrix3x3 mi;
SHint invertible;
SHVector2 corners[4];
SHVector2 fcorners[4];
SHfloat minOffset=0.0f;
SHfloat maxOffset=0.0f;
SHint maxI=0, maxJ=0;
SHfloat maxA=0.0f;
SHfloat startA=0.0f;
int numsteps = 100;
float step = 2*PI/numsteps;
SHVector2 tmin, tmax;
SHVector2 min1, max1, min2, max2;
/* Pick paint transform matrix */
SH_GETCONTEXT(0);
if (mode == VG_FILL_PATH)
m = &context->fillTransform;
else if (mode == VG_STROKE_PATH)
m = &context->strokeTransform;
/* Move focus into circle if outside */
SET2(cf, fx,fy);
SUB2(cf, cx,cy);
n = NORM2(cf);
if (n > r) {
DIV2(cf, n);
fx = cx + 0.995f * r * cf.x;
fy = cy + 0.995f * r * cf.y;
}
/* Precalculations */
rr = r*r;
fcx = fx - cx;
fcy = fy - cy;
C = fcx*fcx + fcy*fcy - rr;
/* Apply paint-to-user transformation
to focus and unit vectors */
SET2(f, fx, fy);
SET2(c, cx, cy);
SET2(ux, 1, 0);
SET2(uy, 0, 1);
ADD2(ux, cx, cy);
ADD2(uy, cx, cy);
TRANSFORM2(f, (*m));
TRANSFORM2(c, (*m));
TRANSFORM2(ux, (*m));
TRANSFORM2(uy, (*m));
SUB2V(ux, c); SUB2V(uy, c);
/* Boundbox corners */
SET2(corners[0], min->x, min->y);
SET2(corners[1], max->x, min->y);
SET2(corners[2], max->x, max->y);
SET2(corners[3], min->x, max->y);
/* Find inverse transformation (back to paint space) */
invertible = shInvertMatrix(m, &mi);
if (!invertible || r <= 0.0f) {
/* Fill boundbox with color at offset 1 */
SHColor *c = &p->stops.items[p->stops.size-1].color;
glColor4fv((GLfloat*)c); glBegin(GL_QUADS);
for (i=0; i<4; ++i) glVertex2fv((GLfloat*)&corners[i]);
glEnd();
return 1;
}
/*--------------------------------------------------------*/
/* Find min/max offset */
for (i=0; i<4; ++i) {
/* Transform to paint space */
SHfloat ax,ay, A,B,D,t, off;
TRANSFORM2TO(corners[i], mi, fcorners[i]);
SUB2(fcorners[i], fx, fy);
n = NORM2(fcorners[i]);
if (n == 0.0f) {
/* Avoid zero-length vectors */
off = 0.0f;
}else{
/* Distance from focus to circle at corner angle */
DIV2(fcorners[i], n);
ax = fcorners[i].x;
ay = fcorners[i].y;
A = ax*ax + ay*ay;
B = 2 * (fcx*ax + fcy*ay);
D = B*B - 4*A*C;
t = (-B + SH_SQRT(D)) / (2*A);
/* Relative offset of boundbox corner */
if (D <= 0.0f) off = 1.0f;
else off = n / t;
}
/* Find smallest and largest offset */
if (off < minOffset || i==0) minOffset = off;
if (off > maxOffset || i==0) maxOffset = off;
}
/* Is transformed focus inside original boundbox? */
if (f.x >= min->x && f.x <= max->x &&
f.y >= min->y && f.y <= max->y) {
/* Draw whole circle */
minOffset = 0.0f;
startA = 0.0f;
maxA = 2*PI;
}else{
/* Find most distant corner pair */
for (i=0; i<3; ++i) {
if (ISZERO2(fcorners[i])) continue;
for (j=i+1; j<4; ++j) {
if (ISZERO2(fcorners[j])) continue;
a = ANGLE2N(fcorners[i], fcorners[j]);
if (a > maxA || maxA == 0.0f)
{maxA=a; maxI=i; maxJ=j;}
}}
/* Pick starting angle */
if (CROSS2(fcorners[maxI],fcorners[maxJ]) > 0.0f)
startA = shVectorOrientation(&fcorners[maxI]);
else startA = shVectorOrientation(&fcorners[maxJ]);
}
/*---------------------------------------------------------*/
/* TODO: for minOffset we'd actually need to find minimum
of the gradient function when X and Y are substitued
with a line equation for each bound-box edge. As a
workaround we use 0.0f for now. */
minOffset = 0.0f;
step = PI/50;
numsteps = (SHint)SH_CEIL(maxA / step) + 1;
glActiveTexture(texUnit);
shSetGradientTexGLState(p);
glEnable(GL_TEXTURE_1D);
glBegin(GL_QUADS);
/* Walk the steps and draw gradient mesh */
for (i=0, a=startA; i<numsteps; ++i, a+=step) {
/* Distance from focus to circle border
at current angle (gradient space) */
float ax = SH_COS(a);
float ay = SH_SIN(a);
float A = ax*ax + ay*ay;
float B = 2 * (fcx*ax + fcy*ay);
float D = B*B - 4*A*C;
float t = (-B + SH_SQRT(D)) / (2*A);
if (D <= 0.0f) t = 0.0f;
/* Vectors pointing towards minimum and maximum
offset at current angle (gradient space) */
tmin.x = ax * t * minOffset;
tmin.y = ay * t * minOffset;
tmax.x = ax * t * maxOffset;
tmax.y = ay * t * maxOffset;
/* Transform back to user space */
min2.x = f.x + tmin.x * ux.x + tmin.y * uy.x;
min2.y = f.y + tmin.x * ux.y + tmin.y * uy.y;
max2.x = f.x + tmax.x * ux.x + tmax.y * uy.x;
max2.y = f.y + tmax.x * ux.y + tmax.y * uy.y;
/* Draw quad */
if (i!=0) {
glMultiTexCoord1f(texUnit, minOffset);
glVertex2fv((GLfloat*)&min1);
glVertex2fv((GLfloat*)&min2);
glMultiTexCoord1f(texUnit, maxOffset);
glVertex2fv((GLfloat*)&max2);
glVertex2fv((GLfloat*)&max1);
}
/* Save prev points */
min1 = min2;
max1 = max2;
}
glEnd();
glDisable(GL_TEXTURE_1D);
return 1;
}
/// Special method for inverting a 2D pose
TRANSFORM2 TRANSFORM2::invert(const TRANSFORM2& p)
{
return TRANSFORM2(p).invert();
}
int shDrawLinearGradientMesh(SHPaint *p, SHVector2 *min, SHVector2 *max,
VGPaintMode mode, GLenum texUnit)
{
SHint i;
SHfloat n;
SHfloat x1 = p->linearGradient[0];
SHfloat y1 = p->linearGradient[1];
SHfloat x2 = p->linearGradient[2];
SHfloat y2 = p->linearGradient[3];
SHVector2 c, ux, uy;
SHVector2 cc, uux, uuy;
SHMatrix3x3 *m;
SHMatrix3x3 mi;
SHint invertible;
SHVector2 corners[4];
SHfloat minOffset = 0.0f;
SHfloat maxOffset = 0.0f;
SHfloat left = 0.0f;
SHfloat right = 0.0f;
SHVector2 l1,r1,l2,r2;
/* Pick paint transform matrix */
SH_GETCONTEXT(0);
if (mode == VG_FILL_PATH)
m = &context->fillTransform;
else if (mode == VG_STROKE_PATH)
m = &context->strokeTransform;
/* Gradient center and unit vectors */
SET2(c, x1, y1);
SET2(ux, x2-x1, y2-y1);
SET2(uy, -ux.y, ux.x);
n = NORM2(ux);
DIV2(ux, n);
NORMALIZE2(uy);
/* Apply paint-to-user transformation */
ADD2V(ux, c); ADD2V(uy, c);
TRANSFORM2TO(c, (*m), cc);
TRANSFORM2TO(ux, (*m), uux);
TRANSFORM2TO(uy, (*m), uuy);
SUB2V(ux,c); SUB2V(uy,c);
SUB2V(uux,cc); SUB2V(uuy,cc);
/* Boundbox corners */
SET2(corners[0], min->x, min->y);
SET2(corners[1], max->x, min->y);
SET2(corners[2], max->x, max->y);
SET2(corners[3], min->x, max->y);
/* Find inverse transformation (back to paint space) */
invertible = shInvertMatrix(m, &mi);
if (!invertible || n==0.0f) {
/* Fill boundbox with color at offset 1 */
SHColor *c = &p->stops.items[p->stops.size-1].color;
glColor4fv((GLfloat*)c); glBegin(GL_QUADS);
for (i=0; i<4; ++i) glVertex2fv((GLfloat*)&corners[i]);
glEnd();
return 1;
}
/*--------------------------------------------------------*/
for (i=0; i<4; ++i) {
/* Find min/max offset and perpendicular span */
SHfloat o, s;
TRANSFORM2(corners[i], mi);
SUB2V(corners[i], c);
o = DOT2(corners[i], ux) / n;
s = DOT2(corners[i], uy);
if (o < minOffset || i==0) minOffset = o;
if (o > maxOffset || i==0) maxOffset = o;
if (s < left || i==0) left = s;
if (s > right || i==0) right = s;
}
/*---------------------------------------------------------*/
/* Corners of boundbox in gradient system */
SET2V(l1, cc); SET2V(r1, cc);
SET2V(l2, cc); SET2V(r2, cc);
OFFSET2V(l1, uuy, left); OFFSET2V(l1, uux, minOffset * n);
OFFSET2V(r1, uuy, right); OFFSET2V(r1, uux, minOffset * n);
OFFSET2V(l2, uuy, left); OFFSET2V(l2, uux, maxOffset * n);
OFFSET2V(r2, uuy, right); OFFSET2V(r2, uux, maxOffset * n);
/* Draw quad using color-ramp texture */
glActiveTexture(texUnit);
shSetGradientTexGLState(p);
glEnable(GL_TEXTURE_1D);
glBegin(GL_QUAD_STRIP);
glMultiTexCoord1f(texUnit, minOffset);
glVertex2fv((GLfloat*)&r1);
glVertex2fv((GLfloat*)&l1);
glMultiTexCoord1f(texUnit, maxOffset);
glVertex2fv((GLfloat*)&r2);
glVertex2fv((GLfloat*)&l2);
glEnd();
glDisable(GL_TEXTURE_1D);
return 1;
}
