-/* $Id: s_texture.c,v 1.12 2001/02/20 16:42:26 brianp Exp $ */
+/* $Id: s_texture.c,v 1.13 2001/02/26 18:24:37 brianp Exp $ */
/*
* Mesa 3-D graphics library
/*
* Used to compute texel locations for linear sampling.
+ * Input:
+ * wrapMode = GL_REPEAT, GL_CLAMP or GL_CLAMP_TO_EDGE
+ * 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) \
{ \
/*
- * Apply a shadow/depth texture to the array of colors.
+ * Sample a shadow/depth texture.
* Input: ctx - context
* texUnit - the texture unit
- * n - number of colors
- * r - array [n] of texture R coordinates
- * In/Out: rgba - array [n] of colors.
+ * n - number of samples
+ * s,t,r - array [n] of texture coordinates
+ * In/Out: rgba - array [n] of texel colors.
*/
static void
sample_depth_texture(const GLcontext *ctx,
GLchan texel[][4])
{
const struct gl_texture_object *texObj = texUnit->_Current;
- const struct gl_texture_image *texImage = texObj->Image[0]; /* XXX hack */
+ const GLint baseLevel = texObj->BaseLevel;
+ const struct gl_texture_image *texImage = texObj->Image[baseLevel];
+ const GLuint width = texImage->Width;
+ const GLuint height = texImage->Height;
const GLchan ambient = texObj->ShadowAmbient;
GLboolean lequal, gequal;
- GLuint i;
+
+ if (texObj->Dimensions != 2) {
+ gl_problem(ctx, "only 2-D depth textures supported at this time");
+ return;
+ }
+
+ if (texObj->MinFilter != texObj->MagFilter) {
+ gl_problem(ctx, "mipmapped depth textures not supported at this time");
+ return;
+ }
+
+ /* XXX the GL_SGIX_shadow extension spec doesn't say what to do if
+ * GL_TEXTURE_COMPARE_SGIX == GL_TRUE but the current texture object
+ * isn't a depth texture.
+ */
+ if (texImage->Format != GL_DEPTH_COMPONENT) {
+ gl_problem(ctx,"GL_TEXTURE_COMPARE_SGIX enabled with non-depth texture");
+ return;
+ }
if (texObj->CompareOperator == GL_TEXTURE_LEQUAL_R_SGIX) {
lequal = GL_TRUE;
gequal = GL_TRUE;
}
- assert(texObj->Dimensions == 2);
- assert(texImage->Format == GL_DEPTH_COMPONENT);
+ if (texObj->MagFilter == GL_NEAREST) {
+ GLuint i;
+ for (i = 0; i < n; i++) {
+ GLfloat depthSample;
+ GLint col, row;
+ COMPUTE_NEAREST_TEXEL_LOCATION(texObj->WrapS, s[i], width, col);
+ COMPUTE_NEAREST_TEXEL_LOCATION(texObj->WrapT, t[i], height, row);
+ depthSample = *((const GLfloat *) texImage->Data + row * width + col);
+ if ((depthSample <= r[i] && lequal) ||
+ (depthSample >= r[i] && gequal)) {
+ texel[i][RCOMP] = ambient;
+ texel[i][GCOMP] = ambient;
+ texel[i][BCOMP] = ambient;
+ texel[i][ACOMP] = CHAN_MAX;
+ }
+ else {
+ texel[i][RCOMP] = CHAN_MAX;
+ texel[i][GCOMP] = CHAN_MAX;
+ texel[i][BCOMP] = CHAN_MAX;
+ texel[i][ACOMP] = CHAN_MAX;
+ }
+ }
+ }
+ else {
+ GLuint i;
+ ASSERT(texObj->MagFilter == GL_LINEAR);
+ for (i = 0; i < n; i++) {
+ GLfloat depth00, depth01, depth10, depth11;
+ GLint i0, i1, j0, j1;
+ GLfloat u, v;
+ GLuint useBorderTexel;
+
+ COMPUTE_LINEAR_TEXEL_LOCATIONS(texObj->WrapS, s[i], u, width, i0, i1);
+ COMPUTE_LINEAR_TEXEL_LOCATIONS(texObj->WrapT, t[i], v, height,j0, j1);
+
+ useBorderTexel = 0;
+ if (texImage->Border) {
+ i0 += texImage->Border;
+ i1 += texImage->Border;
+ j0 += texImage->Border;
+ j1 += texImage->Border;
+ }
+ else {
+ if (i0 < 0 || i0 >= width) useBorderTexel |= I0BIT;
+ if (i1 < 0 || i1 >= width) useBorderTexel |= I1BIT;
+ if (j0 < 0 || j0 >= height) useBorderTexel |= J0BIT;
+ if (j1 < 0 || j1 >= height) useBorderTexel |= J1BIT;
+ }
- for (i = 0; i < n; i++) {
- const GLfloat *src;
- GLfloat depthSample;
- GLint col, row;
- /* XXX this is a hack - implement proper sampling */
- COMPUTE_NEAREST_TEXEL_LOCATION(texObj->WrapS, s[i], texImage->Width, col);
- COMPUTE_NEAREST_TEXEL_LOCATION(texObj->WrapT, t[i], texImage->Height,row);
- src = (const GLfloat *) texImage->Data + row * texImage->Width + col;
- depthSample = *src;
- if ((depthSample <= r[i] && lequal) ||
- (depthSample >= r[i] && gequal)) {
- texel[i][RCOMP] = ambient;
- texel[i][GCOMP] = ambient;
- texel[i][BCOMP] = ambient;
- texel[i][ACOMP] = CHAN_MAX;
+ /* get four depth samples from the texture */
+ if (useBorderTexel & (I0BIT | J0BIT)) {
+ depth00 = 1.0;
+ }
+ else {
+ depth00 = *((const GLfloat *) texImage->Data + j0 * width + i0);
+ }
+ if (useBorderTexel & (I1BIT | J0BIT)) {
+ depth10 = 1.0;
+ }
+ else {
+ depth10 = *((const GLfloat *) texImage->Data + j0 * width + i1);
+ }
+ if (useBorderTexel & (I0BIT | J1BIT)) {
+ depth01 = 1.0;
+ }
+ else {
+ depth01 = *((const GLfloat *) texImage->Data + j1 * width + i0);
+ }
+ if (useBorderTexel & (I1BIT | J1BIT)) {
+ depth11 = 1.0;
+ }
+ else {
+ depth11 = *((const GLfloat *) texImage->Data + j1 * width + i1);
+ }
+
+ if (0) {
+ /* compute a single weighted depth sample and do one comparison */
+ const GLfloat a = FRAC(u);
+ const GLfloat b = FRAC(v);
+ const GLfloat w00 = (1.0F - a) * (1.0F - b);
+ const GLfloat w10 = ( a) * (1.0F - b);
+ const GLfloat w01 = (1.0F - a) * ( b);
+ const GLfloat w11 = ( a) * ( b);
+ const GLfloat depthSample = w00 * depth00 + w10 * depth10
+ + w01 * depth01 + w11 * depth11;
+ if ((depthSample <= r[i] && lequal) ||
+ (depthSample >= r[i] && gequal)) {
+ texel[i][RCOMP] = ambient;
+ texel[i][GCOMP] = ambient;
+ texel[i][BCOMP] = ambient;
+ texel[i][ACOMP] = CHAN_MAX;
+ }
+ else {
+ texel[i][RCOMP] = CHAN_MAX;
+ texel[i][GCOMP] = CHAN_MAX;
+ texel[i][BCOMP] = CHAN_MAX;
+ texel[i][ACOMP] = CHAN_MAX;
+ }
+ }
+ else {
+ /* Do four depth/R comparisons and compute a weighted result.
+ * If this touches on somebody's I.P., I'll remove this code
+ * upon request.
+ */
+ const GLfloat d = (CHAN_MAXF - (GLfloat) ambient) * 0.25F;
+ GLfloat luminance = CHAN_MAXF;
+ GLchan lum;
+ if (lequal) {
+ if (depth00 <= r[i]) luminance -= d;
+ if (depth01 <= r[i]) luminance -= d;
+ if (depth10 <= r[i]) luminance -= d;
+ if (depth11 <= r[i]) luminance -= d;
+ }
+ else {
+ if (depth00 >= r[i]) luminance -= d;
+ if (depth01 >= r[i]) luminance -= d;
+ if (depth10 >= r[i]) luminance -= d;
+ if (depth11 >= r[i]) luminance -= d;
+ }
+ lum = (GLchan) luminance;
+ texel[i][RCOMP] = lum;
+ texel[i][GCOMP] = lum;
+ texel[i][BCOMP] = lum;
+ texel[i][ACOMP] = CHAN_MAX;
+ }
}
- else {
- texel[i][RCOMP] = CHAN_MAX;
- texel[i][GCOMP] = CHAN_MAX;
- texel[i][BCOMP] = CHAN_MAX;
+ }
+}
+
+
+#if 0
+/*
+ * Experimental depth texture sampling function.
+ */
+static void
+sample_depth_texture2(const GLcontext *ctx,
+ const struct gl_texture_unit *texUnit,
+ GLuint n,
+ const GLfloat s[], const GLfloat t[], const GLfloat r[],
+ GLchan texel[][4])
+{
+ const struct gl_texture_object *texObj = texUnit->_Current;
+ const GLint baseLevel = texObj->BaseLevel;
+ const struct gl_texture_image *texImage = texObj->Image[baseLevel];
+ const GLuint width = texImage->Width;
+ const GLuint height = texImage->Height;
+ const GLchan ambient = texObj->ShadowAmbient;
+ GLboolean lequal, gequal;
+
+ if (texObj->Dimensions != 2) {
+ gl_problem(ctx, "only 2-D depth textures supported at this time");
+ return;
+ }
+
+ if (texObj->MinFilter != texObj->MagFilter) {
+ gl_problem(ctx, "mipmapped depth textures not supported at this time");
+ return;
+ }
+
+ /* XXX the GL_SGIX_shadow extension spec doesn't say what to do if
+ * GL_TEXTURE_COMPARE_SGIX == GL_TRUE but the current texture object
+ * isn't a depth texture.
+ */
+ if (texImage->Format != GL_DEPTH_COMPONENT) {
+ gl_problem(ctx,"GL_TEXTURE_COMPARE_SGIX enabled with non-depth texture");
+ return;
+ }
+
+ if (texObj->CompareOperator == GL_TEXTURE_LEQUAL_R_SGIX) {
+ lequal = GL_TRUE;
+ gequal = GL_FALSE;
+ }
+ else {
+ lequal = GL_FALSE;
+ gequal = GL_TRUE;
+ }
+
+ {
+ GLuint i;
+ for (i = 0; i < n; i++) {
+ const GLint K = 3;
+ GLint col, row, ii, jj, imin, imax, jmin, jmax, samples, count;
+ GLfloat w;
+ GLchan lum;
+ COMPUTE_NEAREST_TEXEL_LOCATION(texObj->WrapS, s[i], width, col);
+ COMPUTE_NEAREST_TEXEL_LOCATION(texObj->WrapT, t[i], height, row);
+
+ imin = col - K;
+ imax = col + K;
+ jmin = row - K;
+ jmax = row + K;
+
+ if (imin < 0) imin = 0;
+ if (imax >= width) imax = width - 1;
+ if (jmin < 0) jmin = 0;
+ if (jmax >= height) jmax = height - 1;
+
+ samples = (imax - imin + 1) * (jmax - jmin + 1);
+ count = 0;
+ for (jj = jmin; jj <= jmax; jj++) {
+ for (ii = imin; ii <= imax; ii++) {
+ GLfloat depthSample = *((const GLfloat *) texImage->Data
+ + jj * width + ii);
+ if ((depthSample <= r[i] && lequal) ||
+ (depthSample >= r[i] && gequal)) {
+ count++;
+ }
+ }
+ }
+
+ w = (GLfloat) count / (GLfloat) samples;
+ w = CHAN_MAXF - w * (CHAN_MAXF - (GLfloat) ambient);
+ lum = (GLint) w;
+
+ texel[i][RCOMP] = lum;
+ texel[i][GCOMP] = lum;
+ texel[i][BCOMP] = lum;
texel[i][ACOMP] = CHAN_MAX;
}
}
}
-
+#endif
/*
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