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# Check that triangles delivered to the geometry shader using
# GL_TRIANGLE_STRIP_ADJACENCY have the correct orientation.
#
# This test works by rendering 4 triangles with adjacency in a strip
# and using gl_FrontFacing to check that they all have the same
# orientation.
#
# The layout of the vertices in space is chosen to match the drawing
# in section 10.1.13 (Triangles with Adjacency) of the GL 4.4 spec,
# namely:
#
# 6 10
# |\ |\
# | \| \
# 2--3--7--11
# \ |\ |\ |\
# \| \| \| \
# 1--5--9--12
# \ |\ |
# \| \|
# 4 8
#
# Note that the only triangles drawn by this test are triangles 1-3-5,
# 5-3-7, 5-7-9, and 9-7-11. The other triangles shown in the diagram
# are "adjacent triangles".
#
# Note also that triangles 1-3-5, 5-3-7, 5-7-9, and 9-7-11 are all
# clockwise, so we expect gl_FrontFacing to be false.
[require]
GL >= 2.0
GLSL >= 1.50
[vertex shader]
in vec4 vertex;
out vec4 vertex_to_gs;
void main()
{
vertex_to_gs = vertex;
}
[geometry shader]
layout(triangles_adjacency) in;
layout(triangle_strip, max_vertices = 3) out;
in vec4 vertex_to_gs[6];
void main()
{
for (int i = 0; i < 3; i++) {
gl_Position = vertex_to_gs[2*i];
EmitVertex();
}
}
[fragment shader]
void main()
{
if (!gl_FrontFacing)
gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);
else
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
[vertex data]
vertex/float/2
-0.5 -0.25 #1
-1.0 0.25 #2
-0.5 0.25 #3
0.0 -0.75 #4
0.0 -0.25 #5
-0.5 0.75 #6
0.0 0.25 #7
0.5 -0.75 #8
0.5 -0.25 #9
0.0 0.75 #10
0.5 0.25 #11
1.0 -0.25 #12
[test]
clear color 0.0 0.0 0.0 0.0
clear
draw arrays GL_TRIANGLE_STRIP_ADJACENCY 0 12
# Probe inside each triangle
relative probe rgba (0.33, 0.46) (0.0, 1.0, 0.0, 1.0)
relative probe rgba (0.42, 0.54) (0.0, 1.0, 0.0, 1.0)
relative probe rgba (0.58, 0.46) (0.0, 1.0, 0.0, 1.0)
relative probe rgba (0.67, 0.54) (0.0, 1.0, 0.0, 1.0)
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