rtl/gfx: implement fragment shading

1 files changed, 32 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_lerp.sv b/rtl/gfx/gfx_lerp.sv
new file mode 100644
index 0000000..42e4393
--- /dev/null
+++ b/rtl/gfx/gfx_lerp.sv
@@ -0,0 +1,32 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_lerp
+(
+	input  logic clk,
+
+	input  fixed b1,
+	             b2,
+				 q0,
+	             q1_q0,
+	             q2_q0,
+	input  logic stall,
+
+	output fixed q
+);
+
+	/* Interpolación lineal, trivializada.
+	 *
+	 * Esta es la clave: https://fgiesen.wordpress.com/2013/02/06/the-barycentric-conspirac/
+	 */
+
+	gfx_fixed_fma_dot fma
+	(
+		.c(q0),
+		.a0(b1),
+		.b0(q1_q0),
+		.a1(b2),
+		.b1(q2_q0),
+		.*
+	);
+
+endmodule