--- /dev/null
+/**************************************************************************
+ *
+ * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
+ * All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+/**
+ * Texture sampling
+ *
+ * Authors:
+ * Brian Paul
+ */
+
+
+#include "main/macros.h"
+#include "sp_surface.h"
+#include "sp_surface.h"
+#include "sp_tex_sample.h"
+#include "pipe/p_context.h"
+#include "pipe/p_defines.h"
+#include "pipe/tgsi/core/tgsi_exec.h"
+
+
+#define LERP(T, A, B) ( (A) + (T) * ((B) - (A)) )
+
+
+/**
+ * Do 2D/biliner interpolation of float values.
+ * v00, v10, v01 and v11 are typically four texture samples in a square/box.
+ * a and b are the horizontal and vertical interpolants.
+ * It's important that this function is inlined when compiled with
+ * optimization! If we find that's not true on some systems, convert
+ * to a macro.
+ */
+static INLINE GLfloat
+lerp_2d(GLfloat a, GLfloat b,
+ GLfloat v00, GLfloat v10, GLfloat v01, GLfloat v11)
+{
+ const GLfloat temp0 = LERP(a, v00, v10);
+ const GLfloat temp1 = LERP(a, v01, v11);
+ return LERP(b, temp0, temp1);
+}
+
+
+/**
+ * Apply texture coord wrapping mode and return integer texture
+ * row/column/img index.
+ */
+static INLINE void
+nearest_texcoord(GLuint wrapMode, GLfloat s, GLuint width, GLint *k)
+{
+ /* XXX this arithmetic isn't exactly right, add more wrap modes */
+ switch (wrapMode) {
+ case PIPE_TEX_WRAP_REPEAT:
+ *k = (int) (s * width) % width;
+ break;
+ case PIPE_TEX_WRAP_CLAMP:
+ *k = (int) CLAMP(s, 0.0, 1.0) * width;
+ break;
+ default:
+ assert(0);
+ *k = 0;
+ }
+}
+
+static INLINE void
+linear_texcoord(GLuint wrapMode, GLfloat s, GLuint width, GLint *k0, GLint *k1,
+ GLfloat *a)
+{
+ /* XXX this arithmetic isn't exactly right, add more wrap modes */
+ switch (wrapMode) {
+ case PIPE_TEX_WRAP_REPEAT:
+ *k0 = (int) (s * width) % width;
+ *k1 = (*k0 + 1) % width;
+ break;
+ case PIPE_TEX_WRAP_CLAMP:
+ *k0 = (int) CLAMP(s, 0.0, 1.0) * width;
+ *k1 = (*k0 + 1);
+ if (*k1 >= width)
+ *k1 = width - 1;
+ break;
+ default:
+ assert(0);
+ *k0 = *k1 = 0;
+ }
+ /* kludge the lerp weight: */
+ *a = (s * width) - (int) (s * width);
+}
+
+
+/**
+ * Called via tgsi_sampler::get_sample()
+ * Use the sampler's state setting to get a filtered RGBA value
+ * from the sampler's texture (mipmap tree).
+ *
+ * XXX we can implement many versions of this function, each
+ * tightly coded for a specific combination of sampler state
+ * (nearest + repeat), (bilinear mipmap + clamp), etc.
+ *
+ * The update_samplers() function in st_atom_sampler.c could create
+ * a new tgsi_sampler object for each state combo it finds....
+ */
+void
+sp_get_sample(struct tgsi_sampler *sampler,
+ const GLfloat strq[4], GLfloat rgba[4])
+{
+ struct pipe_context *pipe = (struct pipe_context *) sampler->pipe;
+ struct pipe_surface *ps
+ = pipe->get_tex_surface(pipe, sampler->texture, 0, 0, 0);
+
+ switch (sampler->state->min_filter) {
+ case PIPE_TEX_FILTER_NEAREST:
+ {
+ GLint x, y;
+ nearest_texcoord(sampler->state->wrap_s, strq[0],
+ sampler->texture->width0, &x);
+ nearest_texcoord(sampler->state->wrap_t, strq[1],
+ sampler->texture->height0, &y);
+ ps->get_tile(ps, x, y, 1, 1, rgba);
+ }
+ break;
+ case PIPE_TEX_FILTER_LINEAR:
+ {
+ GLfloat t00[4], t01[4], t10[4], t11[4];
+ GLint x0, y0, x1, y1;
+ GLfloat a, b;
+ linear_texcoord(sampler->state->wrap_s, strq[0],
+ sampler->texture->width0, &x0, &x1, &a);
+ linear_texcoord(sampler->state->wrap_t, strq[1],
+ sampler->texture->height0, &y0, &y1, &b);
+ ps->get_tile(ps, x0, y0, 1, 1, t00);
+ ps->get_tile(ps, x1, y0, 1, 1, t10);
+ ps->get_tile(ps, x0, y1, 1, 1, t01);
+ ps->get_tile(ps, x1, y1, 1, 1, t11);
+
+ rgba[0] = lerp_2d(a, b, t00[0], t10[0], t01[0], t11[0]);
+ rgba[1] = lerp_2d(a, b, t00[1], t10[1], t01[1], t11[1]);
+ rgba[2] = lerp_2d(a, b, t00[2], t10[2], t01[2], t11[2]);
+ rgba[3] = lerp_2d(a, b, t00[3], t10[3], t01[3], t11[3]);
+ }
+ break;
+ default:
+ assert(0);
+ }
+}
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