+
+static void
+clear_tank (atlantisstruct * ap)
+{
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ if (do_gradient && !ap->wire)
+ {
+ static GLint gradient_list = -1;
+ static GLint gradient_tex = -1;
+
+ if (gradient_list == -1)
+ {
+ unsigned char *pixels = 0;
+ int start = 64;
+ int end = start + 128;
+ int size = 4 * (end - start);
+ int i;
+
+ pixels = (unsigned char *) malloc (size);
+ i = 0;
+ while (i < size)
+ {
+ pixels[i++] = 0;
+ pixels[i++] = (start + (i>>2)) * 0.56;
+ pixels[i++] = (start + (i>>2));
+ pixels[i++] = 255;
+ }
+
+ clear_gl_error();
+
+ glGenTextures(1, &gradient_tex);
+ glBindTexture(GL_TEXTURE_1D, gradient_tex);
+
+ glTexImage1D(GL_TEXTURE_1D, 0, 4,
+ (end - start), 0,
+ GL_RGBA, GL_UNSIGNED_BYTE, pixels);
+ check_gl_error ("gradient texture");
+ glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+ glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+
+
+ gradient_list = glGenLists(1);
+ glNewList(gradient_list, GL_COMPILE);
+
+ glDepthMask (False);
+ glDisable(GL_DEPTH_TEST);
+ glDisable(GL_LIGHTING);
+ glDisable(GL_TEXTURE_2D);
+ glEnable(GL_TEXTURE_1D);
+ glBindTexture(GL_TEXTURE_1D, gradient_tex);
+ glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
+ glTexParameterf(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP);
+
+ glMatrixMode(GL_PROJECTION);
+ glPushMatrix();
+ glLoadIdentity();
+ glRotatef(90, 0, 0, 1);
+ glTranslatef(-1, -1, 0);
+ glScalef(2, 2, 1);
+
+ glBegin(GL_QUADS);
+ glTexCoord1i(1); glVertex3i(1, 0, 0);
+ glTexCoord1i(0); glVertex3i(0, 0, 0);
+ glTexCoord1i(0); glVertex3i(0, 1, 0);
+ glTexCoord1i(1); glVertex3i(1, 1, 0);
+ glEnd();
+
+ glPopMatrix();
+
+ glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
+ glDisable(GL_TEXTURE_1D);
+
+ glDepthMask (True);
+ glEnable(GL_DEPTH_TEST);
+ glEnable(GL_CULL_FACE);
+ glEnable(GL_LIGHTING);
+ if (do_texture)
+ glEnable(GL_TEXTURE_2D);
+
+ glEndList();
+ check_gl_error ("gradient list");
+ }
+
+ glCallList(gradient_list);
+ }
+}
+
+