[19/49] wined3d: Rewrite shader_glsl_lrp() to properly take the write mask into account, use the GLSL mix instruction

[H. Verbeet]

Fix the comment to correspond to what the instruction actually does.
This instruction is equivalent to the built in GLSL instruction mix(),
so use that rather than doing it ourselves.

Changelog:
  - Rewrite shader_glsl_lrp() to properly take the write mask into account
  - Use the GLSL mix instruction
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---

 dlls/wined3d/glsl_shader.c |   26 ++++++++++++--------------
 1 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/dlls/wined3d/glsl_shader.c b/dlls/wined3d/glsl_shader.c
index 7f66ba0..c1d8316 100644
--- a/dlls/wined3d/glsl_shader.c
+++ b/dlls/wined3d/glsl_shader.c
@@ -1270,24 +1270,22 @@ void shader_glsl_mnxn(SHADER_OPCODE_ARG* arg) {
 /**
     The LRP instruction performs a component-wise linear interpolation 
     between the second and third operands using the first operand as the
-    blend factor.  Equation:  (dst = src2 * (src1 - src0) + src0)
+    blend factor.  Equation:  (dst = src2 + src0 * (src1 - src2))
+    This is equivalent to mix(src2, src1, src0);
 */
 void shader_glsl_lrp(SHADER_OPCODE_ARG* arg) {
+    char src0_str[100], src1_str[100], src2_str[100];
+    char src0_reg[50], src1_reg[50], src2_reg[50];
+    char src0_mask[6], src1_mask[6], src2_mask[6];
+    DWORD write_mask;
 
-    char tmpLine[256];
-    char dst_str[100], src0_str[100], src1_str[100], src2_str[100];
-    char dst_reg[50], src0_reg[50], src1_reg[50], src2_reg[50];
-    char dst_mask[6], src0_mask[6], src1_mask[6], src2_mask[6];
-   
-    shader_glsl_add_dst_param(arg, arg->dst, 0, dst_reg, dst_mask, dst_str);
-    shader_glsl_add_src_param_old(arg, arg->src[0], arg->src_addr[0], src0_reg, src0_mask, src0_str);
-    shader_glsl_add_src_param_old(arg, arg->src[1], arg->src_addr[1], src1_reg, src1_mask, src1_str);
-    shader_glsl_add_src_param_old(arg, arg->src[2], arg->src_addr[2], src2_reg, src2_mask, src2_str);     
+    write_mask = shader_glsl_append_dst(arg->buffer, arg);
 
-    shader_glsl_add_dst_old(arg->dst, dst_reg, dst_mask, tmpLine);
-    
-    shader_addline(arg->buffer, "%s%s + %s * (%s - %s))%s;\n",
-                   tmpLine, src2_str, src0_str, src1_str, src2_str, dst_mask);
+    shader_glsl_add_src_param(arg, arg->src[0], arg->src_addr[0], write_mask, src0_reg, src0_mask, src0_str);
+    shader_glsl_add_src_param(arg, arg->src[1], arg->src_addr[1], write_mask, src1_reg, src1_mask, src1_str);
+    shader_glsl_add_src_param(arg, arg->src[2], arg->src_addr[2], write_mask, src2_reg, src2_mask, src2_str);
+
+    shader_addline(arg->buffer, "mix(%s, %s, %s));\n", src2_str, src1_str, src0_str);
 }
 
 /** Process the WINED3DSIO_LIT instruction in GLSL: