arb_texture_multisample: add test to check sample positions v3

v3: Made more readable, report observed sample positions of failure.

3 files changed, 262 insertions, 0 deletions

diff --git a/tests/all.tests b/tests/all.tests
index 8334c7fd..495de593 100644
--- a/tests/all.tests
+++ b/tests/all.tests
@@ -897,6 +897,9 @@ for sample_count in MSAA_SAMPLE_COUNTS:
                 spec['ARB_texture_multisample/texelFetch/%d-%s-%s' % (
                     sample_count, stage, sampler)] = \
                     concurrent_test('texelFetch %s %s %d' % (stage, sampler, sample_count))
+    # sample positions
+    spec['ARB_texture_multisample/sample-position/%d' % (sample_count,)] = \
+        concurrent_test('arb_texture_multisample-sample-position %d' % (sample_count,))
 add_concurrent_test(arb_texture_multisample, 'arb_texture_multisample-texstate')
 add_concurrent_test(arb_texture_multisample, 'arb_texture_multisample-errors')
 add_concurrent_test(arb_texture_multisample, 'arb_texture_multisample-sample-mask')
diff --git a/tests/spec/arb_texture_multisample/CMakeLists.gl.txt b/tests/spec/arb_texture_multisample/CMakeLists.gl.txt
index 1339d62e..642418fe 100644
--- a/tests/spec/arb_texture_multisample/CMakeLists.gl.txt
+++ b/tests/spec/arb_texture_multisample/CMakeLists.gl.txt
@@ -18,5 +18,6 @@ piglit_add_executable (arb_texture_multisample-sample-mask sample-mask.c)
 piglit_add_executable (arb_texture_multisample-sample-mask-value sample-mask-value.c)
 piglit_add_executable (arb_texture_multisample-sample-mask-execution sample-mask-execution.c)
 piglit_add_executable (arb_texture_multisample-negative-max-samples negative-max-samples.c)
+piglit_add_executable (arb_texture_multisample-sample-position sample-position.c)
 
 # vim: ft=cmake:
diff --git a/tests/spec/arb_texture_multisample/sample-position.c b/tests/spec/arb_texture_multisample/sample-position.c
new file mode 100644
index 00000000..48e82c78
--- /dev/null
+++ b/tests/spec/arb_texture_multisample/sample-position.c
@@ -0,0 +1,258 @@
+/*
+ * Copyright © The Piglit Project 2013
+ *
+ * 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.
+ *
+ * Authors: Christoph Bumiller
+ */
+#include "piglit-util-gl-common.h"
+
+/* File: sample-position.c
+ *
+ * Tests whether the sample positions reported by the driver via
+ * glGetMultisamplefv correspond to the actually positions used when rendering.
+ *
+ * This test draws creates a 1x1 multisample texture and renders a triangle
+ * covering all of the render target starting at a specific x/y offset from
+ * the left/bottom to test the x/y coordinate.
+ * After each such draw, the value of all the samples is recorded into a buffer
+ * via transform feedback, and the offset is increased slightly.
+ * In the end, the buffer is mapped to check if the correct samples were
+ * covered.
+ */
+
+PIGLIT_GL_TEST_CONFIG_BEGIN
+
+    config.supports_gl_compat_version = 30;
+    config.window_visual = PIGLIT_GL_VISUAL_RGB;
+
+PIGLIT_GL_TEST_CONFIG_END
+
+#define NUM_STEPS   32
+#define MAX_SAMPLES 32
+
+const float inc = 2.0f / (float)NUM_STEPS;
+
+static GLuint buf;
+static GLuint tex;
+static GLuint fbo;
+static GLuint prog_rd, prog_wr;
+
+static int samples = 0;
+
+static void
+draw_ms_triangle(int step, int axis)
+{
+	float p = -1.0f + inc * step;
+	float x = axis ? -1.0f : p;
+	float y = axis ? p : -1.0f;
+
+	float tri[3][2] = { { x, y }, { x + 4.0f, y }, { x, y + 4.0f } };
+
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	glUseProgram(prog_wr);
+
+	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, tri);
+	glEnableVertexAttribArray(0);
+
+	glDrawArrays(GL_TRIANGLES, 0, 3);
+
+	glDisableVertexAttribArray(0);
+}
+
+static void
+read_samples(int step, int axis)
+{
+	int index = step + axis * NUM_STEPS;
+
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glUseProgram(prog_rd);
+
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, tex);
+
+	glBindBufferRange(GL_TRANSFORM_FEEDBACK_BUFFER, 0, buf,
+			  MAX_SAMPLES * sizeof(float) * index,
+			  MAX_SAMPLES * sizeof(float));
+
+	glBeginTransformFeedback(GL_POINTS);
+	glDrawArrays(GL_POINTS, 0, 1);
+	glEndTransformFeedback();
+}
+
+enum piglit_result
+piglit_display(void)
+{
+	int pos_determined[MAX_SAMPLES][2];
+	float pos_expected[MAX_SAMPLES][2];
+	float pos_observed[MAX_SAMPLES][2];
+	float *res;
+	int i, s;
+	enum piglit_result result = PIGLIT_PASS;
+
+	memset(pos_determined, 0, sizeof(pos_determined));
+
+	for (s = 0; s < MAX_SAMPLES; ++s)
+		pos_observed[s][0] = pos_observed[s][1] = -16384.0f;
+
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	for (i = 0; i < samples; ++i)
+		glGetMultisamplefv(GL_SAMPLE_POSITION, i, &pos_expected[i][0]);
+
+	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+
+	for (i = 0; i < NUM_STEPS; ++i) {
+		draw_ms_triangle(i, 0);
+		read_samples(i, 0);
+	}
+	for (i = 0; i < NUM_STEPS; ++i) {
+		draw_ms_triangle(i, 1);
+		read_samples(i, 1);
+	}
+
+	/* Determine sample positions from observed coverage:
+	 */
+	res = glMapBuffer(GL_TRANSFORM_FEEDBACK_BUFFER, GL_READ_ONLY);
+
+	for (i = 0; i < NUM_STEPS; ++i) {
+		/* x/y offset of previous step == position of samples that
+		 * are not covered anymore in this step:
+		 */
+		float p = (float)(i - 1) / (float)NUM_STEPS;
+
+		int base_x = MAX_SAMPLES * i;
+		int base_y = MAX_SAMPLES * (i + NUM_STEPS);
+
+		for (s = 0; s < samples; ++s) {
+			if (!pos_determined[s][0] && res[base_x + s] != 1.0f) {
+				pos_determined[s][0] = 1;
+				pos_observed[s][0] = p;
+			}
+			if (!pos_determined[s][1] && res[base_y + s] != 1.0f) {
+				pos_determined[s][1] = 1;
+				pos_observed[s][1] = p;
+			}
+		}
+	}
+	glUnmapBuffer(GL_TRANSFORM_FEEDBACK_BUFFER);
+
+	/* Compare observed sample positions with reported ones:
+	 */
+	for (s = 0; s < samples; ++s) {
+		if (pos_observed[s][0] != pos_expected[s][0]) {
+			result = PIGLIT_FAIL;
+			fprintf(stderr, "sample %i position incorrect (x axis): "
+				"observed %f, expected %f\n", s,
+				pos_observed[s][0], pos_expected[s][0]);
+		}
+		if (pos_observed[s][1] != pos_expected[s][1]) {
+			result = PIGLIT_FAIL;
+			fprintf(stderr, "sample %i position incorrect (y axis): "
+				"observed %f, expected %f\n", s,
+				pos_observed[s][1], pos_expected[s][1]);
+		}
+	}
+
+	return result;
+}
+
+static const char *vsSourceWr = "#version 130 \n"
+	"attribute vec2 pos;\n"
+	"void main() { \n"
+	"   gl_Position = vec4(pos.x, pos.y, 0.0, 1.0); \n"
+	"} \n";
+
+static const char *vsSourceRd = "#version 130 \n"
+	"#extension GL_ARB_texture_multisample : require\n"
+	"uniform sampler2DMS tex; \n"
+	"out float sample[32]; \n" /* 32 == MAX_SAMPLES */
+	"void main() { \n"
+	"   int i; \n"
+	"   for (i = 0; i < 32; ++i) \n"
+	"      sample[i] = texelFetch(tex, ivec2(0, 0), i).g; \n"
+	"   gl_Position = vec4(0.0); \n"
+	"} \n";
+
+static const char *fsSource = "#version 130 \n"
+	"void main() { \n"
+	"   gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0); \n"
+	"} \n";
+
+void
+piglit_init(int argc, char **argv)
+{
+	static const char *varyings[] = { "sample" };
+	GLuint vs, fs;
+	GLuint max_samples;
+
+	piglit_require_extension("GL_ARB_texture_multisample");
+	piglit_require_extension("GL_EXT_transform_feedback");
+
+	if (argc < 2) {
+		fprintf(stderr, "%s <sample_count>\n", argv[0]);
+		piglit_report_result(PIGLIT_FAIL);
+	}
+	samples = strtoul(argv[1], NULL, 0);
+
+	glGetIntegerv(GL_MAX_SAMPLES, (GLint *)&max_samples);
+	if (samples > max_samples)
+		piglit_report_result(PIGLIT_SKIP);
+
+	fs = piglit_compile_shader_text(GL_FRAGMENT_SHADER, fsSource);
+	vs = piglit_compile_shader_text(GL_VERTEX_SHADER, vsSourceRd);
+	prog_rd = piglit_link_simple_program(vs, fs);
+	vs = piglit_compile_shader_text(GL_VERTEX_SHADER, vsSourceWr);
+	prog_wr = piglit_link_simple_program(vs, fs);
+
+	glTransformFeedbackVaryings(prog_rd,
+				    1, varyings, GL_INTERLEAVED_ATTRIBS);
+	glLinkProgram(prog_rd);
+	glGenBuffers(1, &buf);
+	glBindBuffer(GL_TRANSFORM_FEEDBACK_BUFFER, buf);
+	glBufferData(GL_TRANSFORM_FEEDBACK_BUFFER,
+		     MAX_SAMPLES * sizeof(float) * NUM_STEPS * 2, NULL,
+		     GL_STREAM_DRAW);
+
+	glGenTextures(1, &tex);
+	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, tex);
+	glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples,
+				GL_RGBA8,
+				1, 1, GL_TRUE);
+	glGenFramebuffers(1, &fbo);
+	glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
+			       GL_TEXTURE_2D_MULTISAMPLE, tex, 0);
+
+	glUseProgram(prog_rd);
+	glUniform1i(glGetUniformLocation(prog_rd, "tex"), 0);
+
+	assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) ==
+	       GL_FRAMEBUFFER_COMPLETE);
+
+	glViewport(0, 0, 1, 1);
+
+	glEnable(GL_MULTISAMPLE);
+
+	if (!piglit_check_gl_error(GL_NO_ERROR))
+		piglit_report_result(PIGLIT_FAIL);
+}