Explicitly use std140 layout for uniform blocks

The exact memory layout of an array of uints in a uniform block is
implementation-defined, unless a layout is explictly specified.
So the UniformBufferStorageTestCase would previously fail on an
implementation that uses std140 by default.

Use std140 explicitly -- which implies changing the stride of the
array to 16 bytes -- since std140 is the only layout supported for
uniform blocks in core OpenGL.

Modules: OpenGL
Affects:
GL45-CTS.sparse_buffer_tests.BufferStorageTest

VK-GL-CTS issue: 179

Change-Id: Ib5a996aa55a4c589625c575a1b4a3d252ca8e30c

diff --git a/external/openglcts/modules/gl/gl4cSparseBufferTests.cpp b/external/openglcts/modules/gl/gl4cSparseBufferTests.cpp
index 7ae6abb..efe906b 100644 (file)
--- a/external/openglcts/modules/gl/gl4cSparseBufferTests.cpp
+++ b/external/openglcts/modules/gl/gl4cSparseBufferTests.cpp
@@ -6347,7 +6347,7 @@ bool UniformBufferStorageTestCase::execute(glw::GLuint sparse_bo_storage_flags)
                GLU_EXPECT_NO_ERROR(m_gl.getError(), "glMapBuffer() call failed.");
 
                for (unsigned int n_vertex = 0; n_vertex < m_n_ubo_uints && result_local;
-                        ++n_vertex, ubo_data_offset = static_cast<unsigned int>(ubo_data_offset + sizeof(unsigned int)))
+                        ++n_vertex, ubo_data_offset = static_cast<unsigned int>(ubo_data_offset + 4 * sizeof(unsigned int)))
                {
                        const bool is_ub_data_physically_backed = (ubo_data_offset >= ubo_commit_start_offset &&
                                                                                                           ubo_data_offset < (ubo_commit_start_offset + ubo_commit_size)) ?
@@ -6421,7 +6421,9 @@ bool UniformBufferStorageTestCase::initTestCaseGlobal()
        /* Determine the number of uints we can access at once from a single VS invocation */
        DE_ASSERT(gl_max_uniform_block_size_value >= 1);
 
-       m_n_ubo_uints = static_cast<unsigned int>(gl_max_uniform_block_size_value / sizeof(unsigned int));
+       /* Account for the fact that in std140 layout, array elements will be rounded up
+        * to the size of a vec4, i.e. 16 bytes. */
+       m_n_ubo_uints = static_cast<unsigned int>(gl_max_uniform_block_size_value / (4 * sizeof(unsigned int)));
 
        /* Prepare the test program */
        std::stringstream vs_body_define_sstream;
@@ -6432,7 +6434,7 @@ bool UniformBufferStorageTestCase::initTestCaseGlobal()
                                                                   "\n";
 
        const char* vs_body_main = "\n"
-                                                          "uniform data\n"
+                                                          "layout(std140) uniform data\n"
                                                           "{\n"
                                                           "    uint data_input[N_UBO_UINTS];"
                                                           "};\n"
@@ -6511,10 +6513,10 @@ bool UniformBufferStorageTestCase::initTestCaseGlobal()
        m_ubo_data                         = new (std::nothrow) unsigned char[m_sparse_bo_data_size];
        ubo_data_traveller_ptr = (unsigned int*)m_ubo_data;
 
-       for (unsigned int n_vertex = 0; n_vertex < m_sparse_bo_data_size / sizeof(unsigned int); ++n_vertex)
+       for (unsigned int n_vertex = 0; n_vertex < m_sparse_bo_data_size / (4 * sizeof(unsigned int)); ++n_vertex)
        {
                *ubo_data_traveller_ptr = n_vertex;
-               ubo_data_traveller_ptr++;
+               ubo_data_traveller_ptr += 4;
        }
 
        m_gl.genBuffers(1, &m_helper_bo);