Merge pull request #1321 from asarium/opengl/builtInClipPlane

Use built-in OpenGL clip plane instead of custom variant

Author: The-E

code/def_files/main-f.sdr

@@ -82,10 +82,6 @@ uniform float neardist;
 uniform float middist;
 uniform float fardist;
 #endif
-#ifdef FLAG_CLIP
-uniform int use_clip_plane;
-in float fragClipDistance;
-#endif
 #ifdef FLAG_NORMAL_ALPHA
 uniform vec2 normalAlphaMinMax;
 #endif
@@ -270,9 +266,6 @@ void main()
 	if(fragNotVisible >= 0.9) { discard; }
 #endif
 #ifdef FLAG_SHADOW_MAP
- #ifdef FLAG_CLIP
-	if(use_clip_plane == 1) { if(fragClipDistance <= 0.0) { discard; } }
- #endif
 	// need depth and depth squared for variance shadow maps
 	fragOut0 = vec4(fragPosition.z, fragPosition.z * fragPosition.z * VARIANCE_SHADOW_SCALE_INV, 0.0, 1.0);
 	return;
@@ -444,10 +437,6 @@ void main()
 #ifdef FLAG_NORMAL_ALPHA
 	float normViewOffset = dot(vec3(0.0, 0.0, 1.0), normal);
 	baseColor.a = smoothstep(min(normalAlphaMinMax.x, normalAlphaMinMax.y), max(normalAlphaMinMax.x, normalAlphaMinMax.y), clamp(normalAlphaMinMax.x > normalAlphaMinMax.y ? normViewOffset : 1.0 - normViewOffset, 0.0, 1.0));
-#endif
-#ifdef FLAG_CLIP
-	// for some odd reason if we try to discard the pixel early for plane clipping, it screws up glow maps so let's just do it down here.
-	if(use_clip_plane == 1) { if(fragClipDistance <= 0.0) { discard; } }
 #endif
 	fragOut0 = baseColor;
 #ifdef FLAG_DEFERRED

code/def_files/main-g.sdr

@@ -11,10 +11,6 @@ out vec4 fragTexCoord;
 in float geoNotVisible[];
 out float fragNotVisible;
 #endif
-#ifdef FLAG_CLIP
-in float geoClipDistance[];
-out float fragClipDistance;
-#endif
 void main(void)
 {
 	int instanceID = int(geoInstance[0]);
@@ -31,7 +27,7 @@ void main(void)
 		fragNotVisible = geoNotVisible[0];
 #endif
 #ifdef FLAG_CLIP
-		fragClipDistance = geoClipDistance[0];
+		gl_ClipDistance[0] = gl_in[vert].gl_ClipDistance[0];
 #endif
 		EmitVertex();
 	}

code/def_files/main-v.sdr

@@ -54,13 +54,7 @@ uniform float thruster_scale;
 #endif
 #ifdef FLAG_CLIP
 uniform int use_clip_plane;
-uniform vec3 clip_normal;
-uniform vec3 clip_position;
-#ifdef FLAG_SHADOW_MAP
-out float geoClipDistance;
-#else
-out float fragClipDistance;
-#endif
+uniform vec4 clip_equation;
 #endif
 #ifdef FLAG_TRANSFORM
 #define TEXELS_PER_MATRIX 4
@@ -147,13 +141,11 @@ void main()
 	fragFogDist = clamp((gl_Position.z - fogStart) * 0.75 * fogScale, 0.0, 1.0);
  #endif
  #ifdef FLAG_CLIP
-   float clip_dist = 0.0;
-	if(use_clip_plane == 1) clip_dist = dot(normalize((modelMatrix * orient * vertex).xyz - clip_position), clip_normal);
-  #ifdef FLAG_SHADOW_MAP
-   geoClipDistance = clip_dist;
-  #else
-   fragClipDistance = clip_dist;
-  #endif
+	if(use_clip_plane == 1) {
+		gl_ClipDistance[0] = dot(clip_equation, modelMatrix * orient * vertex);
+	} else {
+		gl_ClipDistance[0] = -1.0f;
+	}
  #endif
  #ifndef FLAG_SHADOW_MAP
 	fragPosition = position;

code/graphics/opengl/gropenglshader.cpp

@@ -184,7 +184,7 @@ static opengl_shader_variant_t GL_shader_variants[] = {
 		"Submodel Transforms" },
 
 	{ SDR_TYPE_MODEL, false, SDR_FLAG_MODEL_CLIP, "FLAG_CLIP", 
-		{ "use_clip_plane", "clip_normal", "clip_position" }, {  },
+		{ "use_clip_plane", "clip_equation" }, {  },
 		"Clip Plane" },
 
 	{ SDR_TYPE_MODEL, false, SDR_FLAG_MODEL_HDR, "FLAG_HDR",

code/graphics/opengl/gropenglstate.cpp

@@ -317,39 +317,19 @@ GLboolean opengl_state::PolygonOffsetFill(GLint state)
 	return save_state;
 }
 
-GLboolean opengl_state::ClipPlane(GLint num, GLint state)
-{
-	Assert( (num >= 0) || (num < (int)(sizeof(clipplane_Status) / sizeof(GLboolean))) );
-
-	GLboolean save_state = clipplane_Status[num];
-
-	if ( !((state == -1) || (state == clipplane_Status[num])) ) {
-		if (state) {
-			Assert( state == GL_TRUE );
-			clipplane_Status[num] = GL_TRUE;
-		} else {
-			clipplane_Status[num] = GL_FALSE;
-		}
-	}
-
-	return save_state;
-}
-
-GLboolean opengl_state::ClipDistance(GLint num, GLint state)
+GLboolean opengl_state::ClipDistance(GLint num, bool state)
 {
 	Assert( (num >= 0) && (num < (int)(sizeof(clipdistance_Status) / sizeof(GLboolean))) );
 
 	GLboolean save_state = clipdistance_Status[num];
 
-	if ( !((state == -1) || (state == clipdistance_Status[num])) ) {
+	if (state != clipdistance_Status[num]) {
 		if (state) {
-			Assert( state == GL_TRUE );
-			//glEnable(GL_CLIP_DISTANCE0+num);
-			clipdistance_Status[num] = GL_TRUE;
+			glEnable(GL_CLIP_DISTANCE0+num);
 		} else {
-			//glDisable(GL_CLIP_DISTANCE0+num);
-			clipdistance_Status[num] = GL_FALSE;
+			glDisable(GL_CLIP_DISTANCE0+num);
 		}
+		clipdistance_Status[num] = state;
 	}
 
 	return save_state;

code/graphics/opengl/gropenglstate.h

@@ -152,7 +152,7 @@ class opengl_state
 		GLboolean polygonoffsetfill_Status;
 		GLboolean normalize_Status;
 		GLboolean clipplane_Status[6];
-		GLboolean clipdistance_Status[6];
+		bool clipdistance_Status[6];
 		GLboolean depthmask_Status;
         GLboolean colormask_Status;
 
@@ -202,8 +202,7 @@ class opengl_state
         GLboolean StencilTest(GLint state = -1);
 		GLboolean CullFace(GLint state = -1);
 		GLboolean PolygonOffsetFill(GLint state = -1);
-		GLboolean ClipPlane(GLint num, GLint state = -1);
-		GLboolean ClipDistance(GLint num, GLint state = -1);
+		GLboolean ClipDistance(GLint num, bool state = false);
 		GLboolean DepthMask(GLint state = -1);
         GLboolean ColorMask(GLint state = -1);
 

code/graphics/opengl/gropengltnl.cpp

@@ -793,26 +793,12 @@ void gr_opengl_start_clip_plane()
 
 void gr_opengl_set_clip_plane(vec3d *clip_normal, vec3d *clip_point)
 {
-	if ( Current_shader != NULL && Current_shader->shader == SDR_TYPE_MODEL) {
-		return;
-	}
-
 	if ( clip_normal == NULL || clip_point == NULL ) {
-		GL_state.ClipPlane(0, GL_FALSE);
+		GL_state.ClipDistance(0, false);
 	} else {
-		GLdouble clip_equation[4];
-
-		clip_equation[0] = (GLdouble)clip_normal->xyz.x;
-		clip_equation[1] = (GLdouble)clip_normal->xyz.y;
-		clip_equation[2] = (GLdouble)clip_normal->xyz.z;
-
-		clip_equation[3] = (GLdouble)(clip_normal->xyz.x * clip_point->xyz.x)
-			+ (GLdouble)(clip_normal->xyz.y * clip_point->xyz.y)
-			+ (GLdouble)(clip_normal->xyz.z * clip_point->xyz.z);
-		clip_equation[3] *= -1.0;
+		Assertion(Current_shader != NULL && Current_shader->shader == SDR_TYPE_MODEL, "Clip planes are only supported by the model shader!");
 
-
-		GL_state.ClipPlane(0, GL_TRUE);
+		GL_state.ClipDistance(0, true);
 	}
 }
 
@@ -902,7 +888,7 @@ void opengl_tnl_set_material(material* material_info, bool set_base_map)
 
 	material::clip_plane &clip_params = material_info->get_clip_plane();
 
-	if ( clip_params.enabled ) {
+	if ( material_info->is_clipped() ) {
 		gr_opengl_set_clip_plane(&clip_params.normal, &clip_params.position);
 	} else {
 		gr_opengl_set_clip_plane(NULL, NULL);
@@ -951,14 +937,18 @@ void opengl_tnl_set_model_material(model_material *material_info)
 	}
 
 	if ( Current_shader->flags & SDR_FLAG_MODEL_CLIP ) {
-		bool clip = material_info->is_clipped();
-
-		if ( clip ) {
+		if (material_info->is_clipped()) {
 			material::clip_plane &clip_info = material_info->get_clip_plane();
 
 			Current_shader->program->Uniforms.setUniformi("use_clip_plane", 1);
-			Current_shader->program->Uniforms.setUniform3f("clip_normal", clip_info.normal);
-			Current_shader->program->Uniforms.setUniform3f("clip_position", clip_info.position);
+
+			vec4 clip_equation;
+			clip_equation.xyzw.x = clip_info.normal.xyz.x;
+			clip_equation.xyzw.y = clip_info.normal.xyz.y;
+			clip_equation.xyzw.z = clip_info.normal.xyz.z;
+			clip_equation.xyzw.w = -vm_vec_dot(&clip_info.normal, &clip_info.position);
+
+			Current_shader->program->Uniforms.setUniform4f("clip_equation", clip_equation);
 		} else {
 			Current_shader->program->Uniforms.setUniformi("use_clip_plane", 0);
 		}