Test that interpolateAtSample returns different results

Adds a new test for interpolateAtSample which captures the results
from the function with each different sample value and ensures that
they are all different. This can be done either with a constant or
non-constant value depending on whether a command line argument is
given.

The other tests for interpolateAtSample always use 0 as the sample ID
so it's not very thorough. Using non-const sampler IDs isn't
implemented in the i965 driver of Mesa but the other tests pass anyway
on a release build because it is hardcoded to use sample 0.

Reviewed-by: Dave Airlie <airlied@redhat.com>

3 files changed, 262 insertions, 0 deletions

diff --git a/tests/all.py b/tests/all.py
index 9af40a1ac..1437194f4 100644
--- a/tests/all.py
+++ b/tests/all.py
@@ -2063,6 +2063,8 @@ with profile.group_manager(
     g(['arb_gpu_shader5-interpolateAtCentroid-noperspective'])
     g(['arb_gpu_shader5-interpolateAtSample'])
     g(['arb_gpu_shader5-interpolateAtSample-nonconst'])
+    g(['arb_gpu_shader5-interpolateAtSample-different'])
+    g(['arb_gpu_shader5-interpolateAtSample-different', 'uniform'])
     g(['arb_gpu_shader5-interpolateAtOffset'])
     g(['arb_gpu_shader5-interpolateAtOffset-nonconst'])
 
diff --git a/tests/spec/arb_gpu_shader5/CMakeLists.gl.txt b/tests/spec/arb_gpu_shader5/CMakeLists.gl.txt
index b25c0d4a1..f6b845b7b 100644
--- a/tests/spec/arb_gpu_shader5/CMakeLists.gl.txt
+++ b/tests/spec/arb_gpu_shader5/CMakeLists.gl.txt
@@ -17,5 +17,6 @@ piglit_add_executable (arb_gpu_shader5-interpolateAtCentroid-centroid interpolat
 piglit_add_executable (arb_gpu_shader5-interpolateAtCentroid-noperspective interpolateAtCentroid-noperspective.c)
 piglit_add_executable (arb_gpu_shader5-interpolateAtSample interpolateAtSample.c)
 piglit_add_executable (arb_gpu_shader5-interpolateAtSample-nonconst interpolateAtSample-nonconst.c)
+piglit_add_executable (arb_gpu_shader5-interpolateAtSample-different interpolateAtSample-different.c)
 piglit_add_executable (arb_gpu_shader5-interpolateAtOffset interpolateAtOffset.c)
 piglit_add_executable (arb_gpu_shader5-interpolateAtOffset-nonconst interpolateAtOffset-nonconst.c)
diff --git a/tests/spec/arb_gpu_shader5/interpolateAtSample-different.c b/tests/spec/arb_gpu_shader5/interpolateAtSample-different.c
new file mode 100644
index 000000000..7552d21de
--- /dev/null
+++ b/tests/spec/arb_gpu_shader5/interpolateAtSample-different.c
@@ -0,0 +1,259 @@
+/*
+ * Copyright (c) 2015 Intel Corporation
+ *
+ * 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.
+ */
+
+/**
+ * @file interpolateAtSample-different.c
+ *
+ * Test ARB_gpu_shader5 interpolateAtSample builtin.
+ *
+ * A 1x1 multisample floating-point framebuffer is created with four
+ * samples. A fragment is then rendered into the FBO four times, once
+ * with interpolation at each different sample location. The
+ * interpolation values are written into the framebuffer and read
+ * back. They are then checked to ensure they are all different and
+ * that they all lie within the fragment.
+ *
+ * interpolateAtSample can be called with const or non-const argument.
+ * If ‘uniform’ is specified on the command line it will use a
+ * non-const argument (via a uniform).
+ */
+
+#include "piglit-util-gl.h"
+
+PIGLIT_GL_TEST_CONFIG_BEGIN
+
+	config.supports_gl_core_version = 32;
+
+	config.window_visual = PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_RGB;
+
+PIGLIT_GL_TEST_CONFIG_END
+
+#define N_SAMPLES 4
+
+static const char
+vertex_shader[] =
+	"#version 150\n"
+	"in vec2 piglit_vertex;\n"
+	"in vec2 piglit_texcoord;\n"
+	"out vec2 texcoord;\n"
+	"\n"
+	"void\n"
+	"main()\n"
+	"{\n"
+	"        gl_Position = vec4(piglit_vertex, 0.0, 1.0);\n"
+	"        texcoord = piglit_texcoord;\n"
+	"}\n";
+
+static const char
+fragment_shader_version[] =
+	"#version 150\n"
+	"#extension GL_ARB_gpu_shader5 : require\n";
+
+static const char
+fragment_shader[] =
+	/* Version header and define for sample_id is added outside of
+	 * this string so that it can decide at runtime whether to use
+	 * a uniform or a constant.
+	 */
+	"in vec2 texcoord;\n"
+	"\n"
+	"void\n"
+	"main()\n"
+	"{\n"
+	"        gl_FragColor.rg = interpolateAtSample(texcoord, sample_id);\n"
+	"        gl_FragColor.ba = vec2(0.0, 1.0);\n"
+	"}\n";
+
+enum piglit_result
+piglit_display(void)
+{
+	/* not used */
+	return PIGLIT_FAIL;
+}
+
+static void
+create_framebuffer(int sample_count,
+		   GLuint *fbo,
+		   GLuint *rb)
+{
+	GLenum status;
+
+	glGenFramebuffers(1, fbo);
+	glBindFramebuffer(GL_FRAMEBUFFER, *fbo);
+	glGenRenderbuffers(1, rb);
+	glBindRenderbuffer(GL_RENDERBUFFER, *rb);
+	if (sample_count > 1)
+		glRenderbufferStorageMultisample(GL_RENDERBUFFER,
+						 sample_count, /* samples */
+						 GL_RG32F,
+						 1, 1 /* width/height */);
+	else
+		glRenderbufferStorage(GL_RENDERBUFFER,
+				      GL_RG32F,
+				      1, 1 /* width/height */);
+	glFramebufferRenderbuffer(GL_FRAMEBUFFER,
+				  GL_COLOR_ATTACHMENT0,
+				  GL_RENDERBUFFER,
+				  *rb);
+
+	status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+	if (status != GL_FRAMEBUFFER_COMPLETE) {
+		fprintf(stderr, "Multisample FBO incomplete\n");
+		piglit_report_result(PIGLIT_SKIP);
+	}
+}
+
+GLuint
+create_program(int sample_id)
+{
+	char shader_source[sizeof fragment_shader +
+			   sizeof fragment_shader_version +
+			   512];
+
+	strcpy(shader_source, fragment_shader_version);
+
+	if (sample_id == -1) {
+		strcat(shader_source, "uniform int sample_id;\n");
+	} else {
+		sprintf(shader_source + sizeof fragment_shader_version - 1,
+			"#define sample_id %i\n",
+			sample_id);
+	}
+
+	strcat(shader_source, fragment_shader);
+
+	return piglit_build_simple_program(vertex_shader, shader_source);
+}
+
+void
+piglit_init(int argc, char**argv)
+{
+	GLuint ms_fbo, ms_rb;
+	GLuint ss_fbo, ss_rb;
+	GLuint programs[N_SAMPLES];
+	bool use_uniform = false;
+	GLuint shader_id_location = -1;
+	GLfloat results[N_SAMPLES][2];
+	bool pass = true;
+	int i, j;
+
+	for (i = 1; i < argc; i++) {
+		if (!strcmp(argv[i], "uniform")) {
+			use_uniform = true;
+		} else {
+			fprintf(stderr, "unknown argument \"%s\"\n", argv[i]);
+			piglit_report_result(PIGLIT_FAIL);
+		}
+	}
+
+	piglit_require_extension("GL_ARB_gpu_shader5");
+	piglit_require_GLSL_version(150);
+
+	if (use_uniform) {
+		programs[0] = create_program(-1);
+		glUseProgram(programs[0]);
+		shader_id_location = glGetUniformLocation(programs[0],
+							  "sample_id");
+	} else {
+		for (i = 0; i < N_SAMPLES; i++)
+			programs[i] = create_program(i);
+	}
+
+	create_framebuffer(N_SAMPLES,
+			   &ms_fbo, &ms_rb);
+	create_framebuffer(1, /* sample_count */
+			   &ss_fbo, &ss_rb);
+
+	glViewport(0, 0, 1, 1);
+
+	for (i = 0; i < N_SAMPLES; i++) {
+		if (use_uniform)
+			glUniform1i(shader_id_location, i);
+		else
+			glUseProgram(programs[i]);
+
+		glBindFramebuffer(GL_FRAMEBUFFER, ms_fbo);
+		glClear(GL_COLOR_BUFFER_BIT);
+		piglit_draw_rect_tex(-1, -1, 2, 2,
+				     0, 0, 1, 1);
+
+		glBindFramebuffer(GL_READ_FRAMEBUFFER, ms_fbo);
+		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, ss_fbo);
+
+		glClear(GL_COLOR_BUFFER_BIT);
+		glBlitFramebuffer(0, 0, /* srcX/Y0 */
+				  1, 1, /* srcX/Y1 */
+				  0, 0, /* dstX/Y0 */
+				  1, 1, /* dstX/Y1 */
+				  GL_COLOR_BUFFER_BIT,
+				  GL_NEAREST);
+
+		glBindFramebuffer(GL_FRAMEBUFFER, ss_fbo);
+
+		glReadPixels(0, 0, /* x/y */
+			     1, 1, /* width/height */
+			     GL_RG, GL_FLOAT,
+			     results[i]);
+	}
+
+	for (i = 0; i < N_SAMPLES; i++) {
+		printf("value at sample %i = %f %f\n",
+		       i,
+		       results[i][0],
+		       results[i][1]);
+	}
+
+	/* Check that the samples are within [0, 1] */
+	for (i = 0; i < N_SAMPLES; i++) {
+		if (results[i][0] < 0.0f || results[i][0] > 1.0f ||
+		    results[i][1] < 0.0f || results[i][1] > 1.0f) {
+			fprintf(stderr,
+				"results for sample %i are out of range\n",
+				i);
+			pass = false;
+		}
+	}
+
+	/* Check that all of the samples are different */
+	for (i = 1; i < N_SAMPLES; i++) {
+		for (j = 0; j < i; j++) {
+			if (results[i][0] == results[j][0] &&
+			    results[i][1] == results[j][1]) {
+				fprintf(stderr,
+					"samples %i and %i have the same "
+					"value\n",
+					i, j);
+				pass = false;
+				break;
+			}
+		}
+	}
+
+	glDeleteFramebuffers(1, &ms_fbo);
+	glDeleteRenderbuffers(1, &ms_rb);
+	glDeleteFramebuffers(1, &ss_fbo);
+	glDeleteRenderbuffers(1, &ss_rb);
+
+	piglit_report_result(pass ? PIGLIT_PASS : PIGLIT_FAIL);
+}
+