s_texsample.h

mesa-6.5-minigui源码

/*
 * These values are used in the fixed-point arithmetic used
 * for linear filtering.
 */
#define WEIGHT_SCALE 65536.0F
#define WEIGHT_SHIFT 16


/*
 * Compute the remainder of a divided by b, but be careful with
 * negative values so that GL_REPEAT mode works right.
 */
static INLINE GLint
repeat_remainder(GLint a, GLint b)
{
   if (a >= 0)
      return a % b;
   else
      return (a + 1) % b + b - 1;
}


/*
 * Used to compute texel locations for linear sampling.
 * Input:
 *    wrapMode = GL_REPEAT, GL_CLAMP, GL_CLAMP_TO_EDGE, GL_CLAMP_TO_BORDER
 *    S = texcoord in [0,1]
 *    SIZE = width (or height or depth) of texture
 * Output:
 *    U = texcoord in [0, width]
 *    I0, I1 = two nearest texel indexes
 */
#define COMPUTE_LINEAR_TEXEL_LOCATIONS(wrapMode, S, U, SIZE, I0, I1)	\
{									\
   if (wrapMode == GL_REPEAT) {						\
      U = S * SIZE - 0.5F;						\
      if (tObj->_IsPowerOfTwo) {					\
         I0 = IFLOOR(U) & (SIZE - 1);					\
         I1 = (I0 + 1) & (SIZE - 1);					\
      }									\
      else {								\
         I0 = repeat_remainder(IFLOOR(U), SIZE);			\
         I1 = repeat_remainder(I0 + 1, SIZE);				\
      }									\
   }									\
   else if (wrapMode == GL_CLAMP_TO_EDGE) {				\
      if (S <= 0.0F)							\
         U = 0.0F;							\
      else if (S >= 1.0F)						\
         U = (GLfloat) SIZE;						\
      else								\
         U = S * SIZE;							\
      U -= 0.5F;							\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
      if (I0 < 0)							\
         I0 = 0;							\
      if (I1 >= (GLint) SIZE)						\
         I1 = SIZE - 1;							\
   }									\
   else if (wrapMode == GL_CLAMP_TO_BORDER) {				\
      const GLfloat min = -1.0F / (2.0F * SIZE);			\
      const GLfloat max = 1.0F - min;					\
      if (S <= min)							\
         U = min * SIZE;						\
      else if (S >= max)						\
         U = max * SIZE;						\
      else								\
         U = S * SIZE;							\
      U -= 0.5F;							\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
   }									\
   else if (wrapMode == GL_MIRRORED_REPEAT) {				\
      const GLint flr = IFLOOR(S);					\
      if (flr & 1)							\
         U = 1.0F - (S - (GLfloat) flr);	/* flr is odd */	\
      else								\
         U = S - (GLfloat) flr;		/* flr is even */		\
      U = (U * SIZE) - 0.5F;						\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
      if (I0 < 0)							\
         I0 = 0;							\
      if (I1 >= (GLint) SIZE)						\
         I1 = SIZE - 1;							\
   }									\
   else if (wrapMode == GL_MIRROR_CLAMP_EXT) {				\
      U = (GLfloat) fabs(S);						\
      if (U >= 1.0F)							\
         U = (GLfloat) SIZE;						\
      else								\
         U *= SIZE;							\
      U -= 0.5F;							\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
   }									\
   else if (wrapMode == GL_MIRROR_CLAMP_TO_EDGE_EXT) {			\
      U = (GLfloat) fabs(S);						\
      if (U >= 1.0F)							\
         U = (GLfloat) SIZE;						\
      else								\
         U *= SIZE;							\
      U -= 0.5F;							\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
      if (I0 < 0)							\
         I0 = 0;							\
      if (I1 >= (GLint) SIZE)						\
         I1 = SIZE - 1;							\
   }									\
   else if (wrapMode == GL_MIRROR_CLAMP_TO_BORDER_EXT) {		\
      const GLfloat min = -1.0F / (2.0F * SIZE);			\
      const GLfloat max = 1.0F - min;					\
      U = (GLfloat) fabs(S);						\
      if (U <= min)							\
         U = min * SIZE;						\
      else if (U >= max)						\
         U = max * SIZE;						\
      else								\
         U *= SIZE;							\
      U -= 0.5F;							\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
   }									\
   else {								\
      ASSERT(wrapMode == GL_CLAMP);					\
      if (S <= 0.0F)							\
         U = 0.0F;							\
      else if (S >= 1.0F)						\
         U = (GLfloat) SIZE;						\
      else								\
         U = S * SIZE;							\
      U -= 0.5F;							\
      I0 = IFLOOR(U);							\
      I1 = I0 + 1;							\
   }									\
}


/*
 * Used to compute texel location for nearest sampling.
 */
#define COMPUTE_NEAREST_TEXEL_LOCATION(wrapMode, S, SIZE, I)		\
{									\
   if (wrapMode == GL_REPEAT) {						\
      /* s limited to [0,1) */						\
      /* i limited to [0,size-1] */					\
      I = IFLOOR(S * SIZE);						\
      if (tObj->_IsPowerOfTwo)						\
         I &= (SIZE - 1);						\
      else								\
         I = repeat_remainder(I, SIZE);					\
   }									\
   else if (wrapMode == GL_CLAMP_TO_EDGE) {				\
      /* s limited to [min,max] */					\
      /* i limited to [0, size-1] */					\
      const GLfloat min = 1.0F / (2.0F * SIZE);				\
      const GLfloat max = 1.0F - min;					\
      if (S < min)							\
         I = 0;								\
      else if (S > max)							\
         I = SIZE - 1;							\
      else								\
         I = IFLOOR(S * SIZE);						\
   }									\
   else if (wrapMode == GL_CLAMP_TO_BORDER) {				\
      /* s limited to [min,max] */					\
      /* i limited to [-1, size] */					\
      const GLfloat min = -1.0F / (2.0F * SIZE);			\
      const GLfloat max = 1.0F - min;					\
      if (S <= min)							\
         I = -1;							\
      else if (S >= max)						\
         I = SIZE;							\
      else								\
         I = IFLOOR(S * SIZE);						\
   }									\
   else if (wrapMode == GL_MIRRORED_REPEAT) {				\
      const GLfloat min = 1.0F / (2.0F * SIZE);				\
      const GLfloat max = 1.0F - min;					\
      const GLint flr = IFLOOR(S);					\
      GLfloat u;							\
      if (flr & 1)							\
         u = 1.0F - (S - (GLfloat) flr);	/* flr is odd */	\
      else								\
         u = S - (GLfloat) flr;		/* flr is even */		\
      if (u < min)							\
         I = 0;								\
      else if (u > max)							\
         I = SIZE - 1;							\
      else								\
         I = IFLOOR(u * SIZE);						\
   }									\
   else if (wrapMode == GL_MIRROR_CLAMP_EXT) {				\
      /* s limited to [0,1] */						\
      /* i limited to [0,size-1] */					\
      const GLfloat u = (GLfloat) fabs(S);				\
      if (u <= 0.0F)							\
         I = 0;								\
      else if (u >= 1.0F)						\
         I = SIZE - 1;							\
      else								\
         I = IFLOOR(u * SIZE);						\
   }									\
   else if (wrapMode == GL_MIRROR_CLAMP_TO_EDGE_EXT) {			\
      /* s limited to [min,max] */					\
      /* i limited to [0, size-1] */					\
      const GLfloat min = 1.0F / (2.0F * SIZE);				\
      const GLfloat max = 1.0F - min;					\
      const GLfloat u = (GLfloat) fabs(S);				\
      if (u < min)							\
         I = 0;								\
      else if (u > max)							\
         I = SIZE - 1;							\
      else								\
         I = IFLOOR(u * SIZE);						\
   }									\
   else if (wrapMode == GL_MIRROR_CLAMP_TO_BORDER_EXT) {		\
      /* s limited to [min,max] */					\
      /* i limited to [0, size-1] */					\
      const GLfloat min = -1.0F / (2.0F * SIZE);			\
      const GLfloat max = 1.0F - min;					\
      const GLfloat u = (GLfloat) fabs(S);				\
      if (u < min)							\
         I = -1;							\
      else if (u > max)							\
         I = SIZE;							\
      else								\
         I = IFLOOR(u * SIZE);						\
   }									\
   else {								\
      ASSERT(wrapMode == GL_CLAMP);					\
      /* s limited to [0,1] */						\
      /* i limited to [0,size-1] */					\
      if (S <= 0.0F)							\
         I = 0;								\
      else if (S >= 1.0F)						\
         I = SIZE - 1;							\
      else								\
         I = IFLOOR(S * SIZE);						\
   }									\
}


/* Power of two image sizes only */
#define COMPUTE_LINEAR_REPEAT_TEXEL_LOCATION(S, U, SIZE, I0, I1)	\
{									\
   U = S * SIZE - 0.5F;							\
   I0 = IFLOOR(U) & (SIZE - 1);						\
   I1 = (I0 + 1) & (SIZE - 1);						\
}


/*
 * Compute linear mipmap levels for given lambda.
 */
#define COMPUTE_LINEAR_MIPMAP_LEVEL(tObj, lambda, level)	\
{								\
   if (lambda < 0.0F)						\
      level = tObj->BaseLevel;					\
   else if (lambda > tObj->_MaxLambda)				\
      level = (GLint) (tObj->BaseLevel + tObj->_MaxLambda);	\
   else								\
      level = (GLint) (tObj->BaseLevel + lambda);		\
}


/*
 * Compute nearest mipmap level for given lambda.
 */
#define COMPUTE_NEAREST_MIPMAP_LEVEL(tObj, lambda, level)	\
{								\
   GLfloat l;							\
   if (lambda <= 0.5F)						\
      l = 0.0F;							\
   else if (lambda > tObj->_MaxLambda + 0.4999F)		\
      l = tObj->_MaxLambda + 0.4999F;				\
   else								\
      l = lambda;						\
   level = (GLint) (tObj->BaseLevel + l + 0.5F);		\
   if (level > tObj->_MaxLevel)					\
      level = tObj->_MaxLevel;					\
}



/*
 * Note, the FRAC macro has to work perfectly.  Otherwise you'll sometimes
 * see 1-pixel bands of improperly weighted linear-sampled texels.  The
 * tests/texwrap.c demo is a good test.
 * Also note, FRAC(x) doesn't truly return the fractional part of x for x < 0.
 * Instead, if x < 0 then FRAC(x) = 1 - true_frac(x).
 */
#define FRAC(f)  ((f) - IFLOOR(f))



/*
 * Bitflags for texture border color sampling.
 */
#define I0BIT   1
#define I1BIT   2
#define J0BIT   4
#define J1BIT   8
#define K0BIT  16
#define K1BIT  32



#if 000
/*
 * Get texture palette entry.
 */
static void
palette_sample(const GLcontext *ctx,
               const struct gl_texture_object *tObj,
               GLint index, GLchan rgba[4] )
{
   const GLchan *palette;
   GLenum format;

   if (ctx->Texture.SharedPalette) {
      ASSERT(ctx->Texture.Palette.Type != GL_FLOAT);
      palette = (const GLchan *) ctx->Texture.Palette.Table;
      format = ctx->Texture.Palette.Format;
   }
   else {
      ASSERT(tObj->Palette.Type != GL_FLOAT);
      palette = (const GLchan *) tObj->Palette.Table;
      format = tObj->Palette.Format;
   }

   switch (format) {
      case GL_ALPHA:
         rgba[ACOMP] = palette[index];
         return;
      case GL_LUMINANCE:
      case GL_INTENSITY:
         rgba[RCOMP] = palette[index];
         return;
      case GL_LUMINANCE_ALPHA:
         rgba[RCOMP] = palette[(index << 1) + 0];
         rgba[ACOMP] = palette[(index << 1) + 1];
         return;
      case GL_RGB:
         rgba[RCOMP] = palette[index * 3 + 0];