Mirror influence of environment texture in Blender viewport

This patch implements Mirror influence for environment textures. Approach matches the one from BI.
{F281871}
See the video https://youtu.be/BskgCv6dcIE
Example: {F281876}
Alexander (Blend4Web Team)

Reviewers: campbellbarton, merwin, brecht

Reviewed By: brecht

Subscribers: TwisterGE, blueprintrandom, youle, Evgeny_Rodygin, AlexKowel, yurikovelenov

Differential Revision: https://developer.blender.org/D1786

3 files changed, 33 insertions, 3 deletions

diff --git a/source/blender/gpu/GPU_material.h b/source/blender/gpu/GPU_material.h
index f150b7215e1..81b08e2b128 100644
--- a/source/blender/gpu/GPU_material.h
+++ b/source/blender/gpu/GPU_material.h
@@ -192,7 +192,8 @@ typedef enum GPUDynamicType {
 	GPU_DYNAMIC_MAT_HARD             = 5  | GPU_DYNAMIC_GROUP_MAT,
 	GPU_DYNAMIC_MAT_EMIT             = 6  | GPU_DYNAMIC_GROUP_MAT,
 	GPU_DYNAMIC_MAT_AMB              = 7  | GPU_DYNAMIC_GROUP_MAT,
-	GPU_DYNAMIC_MAT_ALPHA            = 8  | GPU_DYNAMIC_GROUP_MAT
+	GPU_DYNAMIC_MAT_ALPHA            = 8  | GPU_DYNAMIC_GROUP_MAT,
+	GPU_DYNAMIC_MAT_MIR              = 9  | GPU_DYNAMIC_GROUP_MAT
 } GPUDynamicType;
 
 GPUNodeLink *GPU_attribute(CustomDataType type, const char *name);
@@ -249,7 +250,7 @@ typedef struct GPUShadeInput {
 
 	GPUNodeLink *rgb, *specrgb, *vn, *view, *vcol, *ref;
 	GPUNodeLink *alpha, *refl, *spec, *emit, *har, *amb;
-	GPUNodeLink *spectra;
+	GPUNodeLink *spectra, *mir, *refcol;
 } GPUShadeInput;
 
 typedef struct GPUShadeResult {
diff --git a/source/blender/gpu/intern/gpu_material.c b/source/blender/gpu/intern/gpu_material.c
index bf9fb4cb718..fefc18d017e 100644
--- a/source/blender/gpu/intern/gpu_material.c
+++ b/source/blender/gpu/intern/gpu_material.c
@@ -1270,7 +1270,7 @@ static void do_material_tex(GPUShadeInput *shi)
 			}
 
 			/* mapping */
-			if (mtex->mapto & (MAP_COL + MAP_COLSPEC)) {
+			if (mtex->mapto & (MAP_COL | MAP_COLSPEC | MAP_COLMIR)) {
 				/* stencil maps on the texture control slider, not texture intensity value */
 				if ((rgbnor & TEX_RGB) == 0) {
 					GPU_link(mat, "set_rgb", GPU_uniform(&mtex->r), &tcol);
@@ -1311,6 +1311,20 @@ static void do_material_tex(GPUShadeInput *shi)
 
 					texture_rgb_blend(mat, tcol, shi->specrgb, tin, colspecfac, mtex->blendtype, &shi->specrgb);
 				}
+
+				if(mtex->mapto & MAP_COLMIR) {
+					GPUNodeLink *colmirfac;
+
+					if (mtex->mirrfac == 1.0f) colmirfac = stencil;
+					else GPU_link(mat, "math_multiply", GPU_uniform(&mtex->mirrfac), stencil, &colmirfac);
+
+					/* exception for envmap only */
+					if (tex->type == TEX_ENVMAP && mtex->blendtype == MTEX_BLEND) {
+						GPU_link(mat, "mtex_mirror", tcol, shi->refcol, tin, colmirfac, &shi->refcol);
+					}
+					else
+						texture_rgb_blend(mat, tcol, shi->mir, tin, colmirfac, mtex->blendtype, &shi->mir);
+				}
 			}
 
 			if (!(mat->scene->gm.flag & GAME_GLSL_NO_EXTRA_TEX) && (mtex->mapto & MAP_NORM)) {
@@ -1603,6 +1617,8 @@ void GPU_shadeinput_set(GPUMaterial *mat, Material *ma, GPUShadeInput *shi)
 
 	GPU_link(mat, "set_rgb", GPU_dynamic_uniform(&ma->r, GPU_DYNAMIC_MAT_DIFFRGB, NULL), &shi->rgb);
 	GPU_link(mat, "set_rgb", GPU_dynamic_uniform(&ma->specr, GPU_DYNAMIC_MAT_SPECRGB, NULL), &shi->specrgb);
+	GPU_link(mat, "set_rgb", GPU_dynamic_uniform(&ma->mirr, GPU_DYNAMIC_MAT_MIR, NULL), &shi->mir);
+	GPU_link(mat, "set_rgba_zero", &shi->refcol);
 	GPU_link(mat, "shade_norm", GPU_builtin(GPU_VIEW_NORMAL), &shi->vn);
 
 	if (mat->alpha)
@@ -1723,6 +1739,9 @@ void GPU_shaderesult_set(GPUShadeInput *shi, GPUShadeResult *shr)
 		if (ma->mode & MA_RAMP_COL) ramp_diffuse_result(shi, &shr->combined);
 		if (ma->mode & MA_RAMP_SPEC) ramp_spec_result(shi, &shr->spec);
 
+		if (GPU_link_changed(shi->refcol))
+			GPU_link(mat, "shade_add_mirror", shi->mir, shi->refcol, shr->combined, &shr->combined);
+
 		if (GPU_link_changed(shi->spec) || ma->spec != 0.0f)
 			GPU_link(mat, "shade_add", shr->combined, shr->spec, &shr->combined);
 	}
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index 05853c3e2d3..0471ff3c293 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -923,6 +923,11 @@ void shade_norm(vec3 normal, out vec3 outnormal)
 	outnormal = -normalize(normal);
 }
 
+void mtex_mirror(vec3 tcol, vec4 refcol, float tin, float colmirfac, out vec4 outrefcol)
+{
+    outrefcol = mix(refcol, vec4(1.0, tcol), tin*colmirfac);
+}
+
 void mtex_rgb_blend(vec3 outcol, vec3 texcol, float fact, float facg, out vec3 incol)
 {
 	float facm;
@@ -2058,6 +2063,11 @@ void shade_add_spec(float t, vec3 lampcol, vec3 speccol, out vec3 outcol)
 	outcol = t*lampcol*speccol;
 }
 
+void shade_add_mirror(vec3 mir, vec4 refcol, vec3 combined, out vec3 result)
+{
+    result = mir*refcol.gba + (vec3(1.0) - mir*refcol.rrr)*combined;
+}
+
 void alpha_spec_correction(vec3 spec, float spectra, float alpha, out float outalpha)
 {
 	if (spectra > 0.0) {