Initial revision

1 files changed, 192 insertions, 0 deletions

diff --git a/progs/util/showbuffer.c b/progs/util/showbuffer.c
new file mode 100644
index 00000000000..17f84dc62bd
--- /dev/null
+++ b/progs/util/showbuffer.c
@@ -0,0 +1,192 @@
+/* showbuffer.c */
+
+
+/*
+ * Copy the depth buffer to the color buffer as a grayscale image.
+ * Useful for inspecting the depth buffer values.
+ *
+ * This program is in the public domain.
+ *
+ * Brian Paul   November 4, 1998
+ */
+
+
+#include <assert.h>
+#include <stdlib.h>
+#include <GL/gl.h>
+#include "showbuffer.h"
+
+
+
+/*
+ * Copy the depth buffer values into the current color buffer as a
+ * grayscale image.
+ * Input:  winWidth, winHeight - size of the window
+ *         zBlack - the Z value which should map to black (usually 1)
+ *         zWhite - the Z value which should map to white (usually 0)
+ */
+void
+ShowDepthBuffer( GLsizei winWidth, GLsizei winHeight,
+                 GLfloat zBlack, GLfloat zWhite )
+{
+   GLfloat *depthValues;
+
+   assert(zBlack >= 0.0);
+   assert(zBlack <= 1.0);
+   assert(zWhite >= 0.0);
+   assert(zWhite <= 1.0);
+   assert(zBlack != zWhite);
+
+   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+   glPixelStorei(GL_PACK_ALIGNMENT, 1);
+
+   /* Read depth values */
+   depthValues = (GLfloat *) malloc(winWidth * winHeight * sizeof(GLfloat));
+   assert(depthValues);
+   glReadPixels(0, 0, winWidth, winHeight, GL_DEPTH_COMPONENT,
+                GL_FLOAT, depthValues);
+
+   /* Map Z values from [zBlack, zWhite] to gray levels in [0, 1] */
+   /* Not using glPixelTransfer() because it's broke on some systems! */
+   if (zBlack != 0.0 || zWhite != 1.0) {
+      GLfloat scale = 1.0 / (zWhite - zBlack);
+      GLfloat bias = -zBlack * scale;
+      int n = winWidth * winHeight;
+      int i;
+      for (i = 0; i < n; i++)
+         depthValues[i] = depthValues[i] * scale + bias;
+   }
+
+   /* save GL state */
+   glPushAttrib(GL_CURRENT_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT |
+                GL_TRANSFORM_BIT | GL_VIEWPORT_BIT);
+
+   /* setup raster pos for glDrawPixels */
+   glMatrixMode(GL_PROJECTION);
+   glPushMatrix();
+   glLoadIdentity();
+
+   glOrtho(0.0, (GLdouble) winWidth, 0.0, (GLdouble) winHeight, -1.0, 1.0);
+   glMatrixMode(GL_MODELVIEW);
+   glPushMatrix();
+   glLoadIdentity();
+
+   glDisable(GL_STENCIL_TEST);
+   glDisable(GL_DEPTH_TEST);
+   glRasterPos2f(0, 0);
+
+   glDrawPixels(winWidth, winHeight, GL_LUMINANCE, GL_FLOAT, depthValues);
+
+   glPopMatrix();
+   glMatrixMode(GL_PROJECTION);
+   glPopMatrix();
+   free(depthValues);
+
+   glPopAttrib();
+}
+
+
+
+
+/*
+ * Copy the alpha channel values into the current color buffer as a
+ * grayscale image.
+ * Input:  winWidth, winHeight - size of the window
+ */
+void
+ShowAlphaBuffer( GLsizei winWidth, GLsizei winHeight )
+{
+   GLubyte *alphaValues;
+
+   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+   glPixelStorei(GL_PACK_ALIGNMENT, 1);
+
+   /* Read alpha values */
+   alphaValues = (GLubyte *) malloc(winWidth * winHeight * sizeof(GLubyte));
+   assert(alphaValues);
+   glReadPixels(0, 0, winWidth, winHeight, GL_ALPHA, GL_UNSIGNED_BYTE, alphaValues);
+
+   /* save GL state */
+   glPushAttrib(GL_CURRENT_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL |
+                GL_TRANSFORM_BIT | GL_VIEWPORT_BIT);
+
+   /* setup raster pos for glDrawPixels */
+   glMatrixMode(GL_PROJECTION);
+   glPushMatrix();
+   glLoadIdentity();
+
+   glOrtho(0.0, (GLdouble) winWidth, 0.0, (GLdouble) winHeight, -1.0, 1.0);
+   glMatrixMode(GL_MODELVIEW);
+   glPushMatrix();
+   glLoadIdentity();
+
+   glDisable(GL_STENCIL_TEST);
+   glDisable(GL_DEPTH_TEST);
+   glRasterPos2f(0, 0);
+
+   glDrawPixels(winWidth, winHeight, GL_LUMINANCE, GL_UNSIGNED_BYTE, alphaValues);
+
+   glPopMatrix();
+   glMatrixMode(GL_PROJECTION);
+   glPopMatrix();
+   free(alphaValues);
+
+   glPopAttrib();
+}
+
+
+
+/*
+ * Copy the stencil buffer values into the current color buffer as a
+ * grayscale image.
+ * Input:  winWidth, winHeight - size of the window
+ *         scale, bias - scale and bias to apply to stencil values for display
+ */
+void
+ShowStencilBuffer( GLsizei winWidth, GLsizei winHeight,
+                   GLfloat scale, GLfloat bias )
+{
+   GLubyte *stencilValues;
+
+   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+   glPixelStorei(GL_PACK_ALIGNMENT, 1);
+
+   /* Read stencil values */
+   stencilValues = (GLubyte *) malloc(winWidth * winHeight * sizeof(GLubyte));
+   assert(stencilValues);
+   glReadPixels(0, 0, winWidth, winHeight, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, stencilValues);
+
+   /* save GL state */
+   glPushAttrib(GL_CURRENT_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT |
+                GL_PIXEL_MODE_BIT | GL_TRANSFORM_BIT | GL_VIEWPORT_BIT);
+
+   /* setup raster pos for glDrawPixels */
+   glMatrixMode(GL_PROJECTION);
+   glPushMatrix();
+   glLoadIdentity();
+
+   glOrtho(0.0, (GLdouble) winWidth, 0.0, (GLdouble) winHeight, -1.0, 1.0);
+   glMatrixMode(GL_MODELVIEW);
+   glPushMatrix();
+   glLoadIdentity();
+
+   glDisable(GL_STENCIL_TEST);
+   glDisable(GL_DEPTH_TEST);
+   glRasterPos2f(0, 0);
+
+   glPixelTransferf(GL_RED_SCALE, scale);
+   glPixelTransferf(GL_RED_BIAS, bias);
+   glPixelTransferf(GL_GREEN_SCALE, scale);
+   glPixelTransferf(GL_GREEN_BIAS, bias);
+   glPixelTransferf(GL_BLUE_SCALE, scale);
+   glPixelTransferf(GL_BLUE_BIAS, bias);
+
+   glDrawPixels(winWidth, winHeight, GL_LUMINANCE, GL_UNSIGNED_BYTE, stencilValues);
+
+   glPopMatrix();
+   glMatrixMode(GL_PROJECTION);
+   glPopMatrix();
+   free(stencilValues);
+
+   glPopAttrib();
+}