[Piglit] [PATCH 1/2] ext_framebuffer_multisample_blit_scaled: Simplify the shader code

[Anuj Phogat]

Other than simplifications there are few changes to make the shader
look like the one in Mesa. This will make it easier to port the
future changes to the test shader from driver shader code.

Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
---
 .../blit-scaled.cpp                                | 59 ++++++++++------------
 1 file changed, 28 insertions(+), 31 deletions(-)

diff --git a/tests/spec/ext_framebuffer_multisample_blit_scaled/blit-scaled.cpp b/tests/spec/ext_framebuffer_multisample_blit_scaled/blit-scaled.cpp
index a192655..b1c1f1c 100644
--- a/tests/spec/ext_framebuffer_multisample_blit_scaled/blit-scaled.cpp
+++ b/tests/spec/ext_framebuffer_multisample_blit_scaled/blit-scaled.cpp
@@ -76,51 +76,43 @@ compile_shader(GLenum target)
 		"#version 130\n"
 		"in vec2 piglit_vertex;\n"
 		"in vec2 piglit_texcoord;\n"
-		"out vec2 textureCoord;\n"
+		"out vec2 texCoords;\n"
 		"void main()\n"
 		"{\n"
 		"  gl_Position = vec4(piglit_vertex, 0.0, 1.0);\n"
-		"  textureCoord = piglit_texcoord;\n"
+		"  texCoords = piglit_texcoord;\n"
 		"}\n";
 	/* Bilinear filtering of samples using shader program */
 	static const char *frag_template =
 		"#version 130\n"
 		"#extension GL_ARB_texture_multisample : require\n"
-		"in vec2 textureCoord;\n"
 		"uniform %s texSampler;\n"
-		"uniform float src_width;\n"
-		"uniform float src_height;\n"
+		"uniform float src_width, src_height;\n"
+		"in vec2 texCoords;\n"
 		"out vec4 out_color;\n"
 		"void main()\n"
 		"{\n"
 		"%s"
-		"  float x_f, y_f;\n"
-		"  const float x_scale = 2.0f, x_scale_inv = 0.5f;\n"
-		"  const float y_scale = %ff, y_scale_inv = %ff;\n"
-		"  const float x_offset = 0.25f, y_offset = %ff;\n"
+		"  vec2 interp;\n"
+		"  const vec2 scale = vec2(%ff, %ff);\n"
+		"  const vec2 scale_inv = vec2(%ff, %ff);\n"
+		"  const vec2 s_0_offset = vec2(%ff, %ff);\n"
 		"  vec2 s_0_coord, s_1_coord, s_2_coord, s_3_coord;\n"
 		"  vec4 s_0_color, s_1_color, s_2_color, s_3_color;\n"
 		"  vec4 x_0_color, x_1_color;\n"
+		"  vec2 tex_coord = texCoords - s_0_offset;\n"
 		"\n"
-		"  vec2 tex_coord = vec2(textureCoord.x - x_offset,\n"
-		"                        textureCoord.y - y_offset);\n"
-		"  tex_coord = vec2(x_scale * tex_coord.x, y_scale * tex_coord.y);\n"
-		"\n"
-		"  clamp(tex_coord.x, 0.0f, x_scale * src_width - 1.0f);\n"
-		"  clamp(tex_coord.y, 0.0f, y_scale * src_height - 1.0f);\n"
-		"\n"
-		"  x_f = fract(tex_coord.x);\n"
-		"  y_f = fract(tex_coord.y);\n"
-		"\n"
-		"  tex_coord.x = int(tex_coord.x) * x_scale_inv;\n"
-		"  tex_coord.y = int(tex_coord.y) * y_scale_inv;\n"
-		"\n"
+		"  tex_coord *= scale;\n"
+		"  tex_coord.x = clamp(tex_coord.x, 0.0f, scale.x * src_width - 1.0f);\n"
+		"  tex_coord.y = clamp(tex_coord.y, 0.0f, scale.y * src_height - 1.0f);\n"
+		"  interp = fract(tex_coord);\n"
+		"  tex_coord = ivec2(tex_coord) * scale_inv;\n"
 		"\n"
 		"  /* Compute the sample coordinates used for filtering. */\n"
 		"  s_0_coord = tex_coord;\n"
-		"  s_1_coord = tex_coord + vec2(x_scale_inv, 0.0f);\n"
-		"  s_2_coord = tex_coord + vec2(0.0f, y_scale_inv);\n"
-		"  s_3_coord = tex_coord + vec2(x_scale_inv, y_scale_inv);\n"
+		"  s_1_coord = tex_coord + vec2(scale_inv.x, 0.0f);\n"
+		"  s_2_coord = tex_coord + vec2(0.0f, scale_inv.y);\n"
+		"  s_3_coord = tex_coord + vec2(scale_inv.x, scale_inv.y);\n"
 		"\n"
 		"  /* Fetch sample color values. */\n"
 		"%s"
@@ -131,14 +123,17 @@ compile_shader(GLenum target)
 		"#undef TEXEL_FETCH\n"
 		"\n"
 		"  /* Do bilinear filtering on sample colors. */\n"
-		"  x_0_color =  mix(s_0_color, s_1_color, x_f);\n"
-		"  x_1_color =  mix(s_2_color, s_3_color, x_f);\n"
-		"  out_color = mix(x_0_color, x_1_color, y_f);\n"
+		"  x_0_color = mix(s_0_color, s_1_color, interp.x);\n"
+		"  x_1_color = mix(s_2_color, s_3_color, interp.x);\n"
+		"  out_color = mix(x_0_color, x_1_color, interp.y);\n"
 		"}\n";
 
 	char* frag, *texel_fetch_macro;
 	const char*sample_number, *sample_map = "";
-	const float y_scale = samples * 0.5;
+	float x_scale, y_scale;
+
+	x_scale = 2;
+	y_scale = samples / x_scale;
 
 	/* Below switch is used to setup the shader expression, which computes
 	 * sample index and map it to to a sample number on Intel hardware.
@@ -205,8 +200,10 @@ compile_shader(GLenum target)
 	}
 
 	(void)!asprintf(&frag, frag_template, target_string, sample_map,
-		 y_scale, 1.0f / y_scale,
-		 1.0f / samples, texel_fetch_macro);
+		 x_scale, y_scale,
+		 1.0f / x_scale, 1.0f / y_scale,
+		 0.5f / x_scale, 0.5f / y_scale,
+		 texel_fetch_macro);
 
 	/* Compile program */
 	prog = piglit_build_simple_program(vert, frag);
-- 
2.5.5