The ‘first’ parameter should not affect the value of gl_BaseVertex put
it should be added to gl_VertexID. This patch adds an extra rectangle
to the drawn area to test a non-zero ‘first’ parameter. This is worth
testing because Mesa is currently getting this wrong.
---
tests/spec/arb_shader_draw_parameters/basevertex.c | 52 ++++++++++++++++++----
1 file changed, 44 insertions(+), 8 deletions(-)
diff --git a/tests/spec/arb_shader_draw_parameters/basevertex.c
b/tests/spec/arb_shader_draw_parameters/basevertex.c
index 2279e0f..333d4e2 100644
--- a/tests/spec/arb_shader_draw_parameters/basevertex.c
+++ b/tests/spec/arb_shader_draw_parameters/basevertex.c
@@ -24,10 +24,26 @@
/**
* \file basevertex.c
*
- * Test that gl_BaseVertexARB has the correct values. Draw left side
- * of window with a non-base-vertex draw call to verify
- * gl_BaseVertexARB is 0 in that case, then draw other half with base
- * vertex 4 and verifies that that works.
+ * Test that gl_BaseVertexARB has the correct values.
+ *
+ * The framebuffer is filled with three quads like this:
+ *
+ * #########
+ * # # #
+ * # # B #
+ * # A #####
+ * # # C #
+ * # # #
+ * #########
+ *
+ * Quad A is rendered using a non-base-vertex draw call to verify that
+ * gl_BaseVertexARB is zero in that case.
+ *
+ * Quad B is rendered with baseVertex as 4.
+ *
+ * Quad C is rendered using a non-indexed draw call with a non-zero
+ * ‘first’ parameter. This shouldn’t affect gl_BaseVertex but it
+ * should affect gl_VertexID.
*/
#include "piglit-util-gl.h"
@@ -104,19 +120,27 @@ piglit_display()
{
bool pass;
- static const float vertex_array[16] = {
+ static const float vertex_array[24] = {
+ /* Left half of the screen */
-1, -1,
0, -1,
0, 1,
-1, 1,
- 0, -1,
- 1, -1,
+ /* Top-right quarter of the screen */
+ 0, 0,
+ 1, 0,
1, 1,
0, 1,
+
+ /* Bottom-right quarter of the screen */
+ 0, -1,
+ 1, -1,
+ 0, 0,
+ 1, 0,
};
- static const int reference_array[32] = {
+ static const int reference_array[48] = {
0, 0, 0, 0,
0, 0, 1, 0,
0, 0, 2, 0,
@@ -125,6 +149,10 @@ piglit_display()
4, 7, 1, 0,
4, 7, 2, 0,
4, 7, 3, 0,
+ 0, 0, 8, 0,
+ 0, 0, 9, 0,
+ 0, 0, 10, 0,
+ 0, 0, 11, 0,
};
const int indices[6] = {
@@ -167,6 +195,14 @@ piglit_display()
4, /* basevertex */
7 /* baseinstance */);
+ /* Test using glDrawArrays with a non-zero ‘first’ parameter.
+ * This value should be included in gl_VertexID but not in
+ * gl_BaseVertex.
+ */
+ glDrawArrays(GL_TRIANGLE_STRIP,
+ 8, /* first */
+ 4 /* count */);
+
pass = piglit_probe_rect_rgba(0, 0, piglit_width, piglit_height,
green);
