Gawain: allow partial vertex specification

If you don’t specify a vertex’s color, it will use the color of the
previous vertex. Similar for all other attributes.

This matches the legacy behavior of glColor, glNormal, etc. *except* in
Gawain the first vertex of each immBegin must be fully specified. There
is no “current” color in the new system.

1 files changed, 22 insertions, 3 deletions

diff --git a/source/blender/gpu/intern/gpu_immediate.c b/source/blender/gpu/intern/gpu_immediate.c
index 628c8d1c30d..5912570f1c4 100644
--- a/source/blender/gpu/intern/gpu_immediate.c
+++ b/source/blender/gpu/intern/gpu_immediate.c
@@ -621,14 +621,33 @@ void immEndVertex()
 	{
 #if TRUST_NO_ONE
 	assert(imm.primitive != GL_NONE); // make sure we're between a Begin/End pair
+	assert(imm.vertex_idx < imm.vertex_ct);
+#endif
 
 	// have all attribs been assigned values?
+	// if not, copy value from previous vertex
 	const unsigned short all_bits = ~(0xFFFFU << imm.vertex_format.attrib_ct);
-	assert(imm.attrib_value_bits == all_bits);
-	
-	assert(imm.vertex_idx < imm.vertex_ct);
+	if (imm.attrib_value_bits != all_bits)
+		{
+#if TRUST_NO_ONE
+		assert(imm.vertex_idx > 0); // first vertex must have all attribs specified
 #endif
 
+		for (unsigned a_idx = 0; a_idx < imm.vertex_format.attrib_ct; ++a_idx)
+			{
+			const uint16_t mask = 1 << a_idx;
+			if ((imm.attrib_value_bits & mask) == 0)
+				{
+				const Attrib* a = imm.vertex_format.attribs + a_idx;
+
+//				printf("copying %s from vertex %u to %u\n", a->name, imm.vertex_idx - 1, imm.vertex_idx);
+
+				GLubyte* data = imm.vertex_data + a->offset;
+				memcpy(data, data - imm.vertex_format.stride, a->sz);
+				}
+			}
+		}
+	
 	imm.vertex_idx++;
 	imm.vertex_data += imm.vertex_format.stride;
 	imm.attrib_value_bits = 0;