drawpix-z: test glDrawPixels(GL_DEPTH_COMPONENT)

v2: simplify the Z coord code: use [0,1] range for Z for all drawing.

Reviewed-by: Eric Anholt <eric@anholt.net>

2 files changed, 137 insertions, 0 deletions

diff --git a/tests/general/CMakeLists.gl.txt b/tests/general/CMakeLists.gl.txt
index 2318709e..bf4dbe03 100644
--- a/tests/general/CMakeLists.gl.txt
+++ b/tests/general/CMakeLists.gl.txt
@@ -51,6 +51,7 @@ piglit_add_executable (draw-sync draw-sync.c)
 piglit_add_executable (draw-pixels draw-pixels.c)
 piglit_add_executable (draw-vertices draw-vertices.c)
 piglit_add_executable (draw-vertices-half-float draw-vertices-half-float.c)
+piglit_add_executable (drawpix-z drawpix-z.c)
 piglit_add_executable (fog-modes fog-modes.c)
 IF (UNIX)
 	target_link_libraries (fog-modes m)
diff --git a/tests/general/drawpix-z.c b/tests/general/drawpix-z.c
new file mode 100644
index 00000000..58f0a89b
--- /dev/null
+++ b/tests/general/drawpix-z.c
@@ -0,0 +1,136 @@
+/*
+ * Copyright 2012 VMware, Inc.
+ *
+ * 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, sublicense,
+ * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS 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.
+ */
+
+/**
+ * Test glDrawPixels(GL_DEPTH_COMPONENT)
+ * Brian Paul
+ * June 2012
+ *
+ * We don't rely on glReadPixels(GL_DEPTH_COMPONENT) in case it's not
+ * working.  Instead we test by drawing an image into the depth buffer
+ * while setting the color buffer to white.  Next, we draw quads just
+ * in front and behind where we expect the Z values to be.  The quad
+ * behind should be invisible while the quad in front should be totally
+ * visible.
+ */
+
+#include "piglit-util.h"
+
+int piglit_width = 200, piglit_height = 200;
+int piglit_window_mode = GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH;
+
+
+static void
+draw_z_gradient(GLfloat zLeft, GLfloat zRight)
+{
+	GLfloat verts[4][3];
+
+	verts[0][0] = -1.0;  verts[0][1] = -1.0;  verts[0][2] = zLeft;
+	verts[1][0] =  1.0;  verts[1][1] = -1.0;  verts[1][2] = zRight;
+	verts[2][0] =  1.0;  verts[2][1] =  1.0;  verts[2][2] = zRight;
+	verts[3][0] = -1.0;  verts[3][1] =  1.0;  verts[3][2] = zLeft;
+
+	glEnableClientState(GL_VERTEX_ARRAY);
+	glVertexPointer(3, GL_FLOAT, 0, verts);
+	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+}
+
+
+enum piglit_result
+piglit_display(void)
+{
+	/* a tight epsilon isn't important for this test */
+	const GLfloat epsilon = 4.0 / piglit_width;
+	static const GLfloat white[4] = { 1, 1, 1, 1 };
+	static const GLfloat green[4] = { 0, 1, 0, 1 };
+	static const GLfloat red[4] = { 1, 0, 0, 1 };
+	GLfloat *buf;
+	bool pass = true;
+	int i, j;
+	float zLeft, zRight;
+
+	/* For both glDrawPixels and the polygon rendering below we
+	 * use a range of Z values in [0, 1] where 0=near and 1=far.
+	 * So object Z coords are the same as normalized depth coords.
+	 */
+
+	zLeft = epsilon;
+	zRight = 1.0 - epsilon;
+
+	/* create image of Z values increasing from left to right */
+	buf = (GLfloat *)
+		malloc(piglit_width * piglit_height * sizeof(GLfloat));
+	for (j = 0; j < piglit_height; j++) {
+		for (i = 0; i < piglit_width; i++) {
+			float z = i / (float) (piglit_width - 1);
+			z = zLeft + z * (zRight - zLeft);
+			buf[j * piglit_width + i] = z;
+		}
+	}
+
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+	/* glDrawPixels the Z gradient image */
+	glColor4fv(white);
+	glWindowPos2i(0, 0);
+	glDrawPixels(piglit_width, piglit_height,
+		     GL_DEPTH_COMPONENT, GL_FLOAT, buf);
+
+	free(buf);
+
+	/* draw a red quad behind the Z gradient - it should not be visible */
+	glColor4fv(red);
+	draw_z_gradient(zLeft + epsilon, zRight + epsilon);
+	if (!piglit_probe_rect_rgb(0, 0, piglit_width, piglit_height, white)) {
+		printf("Quad behind test failed\n");
+		pass = false;
+	}
+
+	/* draw green quad in front of the Z gradient - it should be visible */
+	glColor4fv(green);
+	draw_z_gradient(zLeft - epsilon, zRight - epsilon);
+	if (!piglit_probe_rect_rgb(0, 0, piglit_width, piglit_height, green)) {
+		printf("Quad in front test failed\n");
+		pass = false;
+	}
+
+	piglit_present_results();
+
+	return pass ? PIGLIT_PASS : PIGLIT_FAIL;
+}
+
+
+void
+piglit_init(int argc, char **argv)
+{
+	/* Setup projection matrix such that zObj=0 becomes zBuffer=0
+	 * and zObj=1 becomes zBuffer=1 (identity transform).
+	 * So, glOrtho maps zObj=0 to zNDC=-1 and maps zObj=1 to zNDC=1.
+	 * Then, zNDC=-1 maps to zBuffer=0 and zNDC=1 maps to zBuffer=1.
+	 */
+	glMatrixMode(GL_PROJECTION);
+	glLoadIdentity();
+	glOrtho(-1.0, 1.0, -1.0, 1.0, 0.0, -1.0);
+
+	glEnable(GL_DEPTH_TEST);
+}