ReignEngine: Implement alpha mapping

shaders/reign.f.glsl

@@ -31,6 +31,7 @@ struct dir_light {
 
 uniform sampler2D tex;
 uniform sampler2D specular_texture;
+uniform sampler2D alpha_texture;
 uniform sampler2D light_texture;
 uniform sampler2D shadow_texture;
 uniform float alpha_mod;
@@ -52,6 +53,7 @@ uniform int fog_type;
 uniform float fog_near;
 uniform float fog_far;
 uniform vec3 fog_color;
+uniform bool use_alpha_map;
 
 in vec2 tex_coord;
 in vec2 light_tex_coord;
@@ -135,5 +137,11 @@ void main() {
 		frag_rgb *= shadow_factor;
 	}
 
-	frag_color = vec4(frag_rgb, texel.a * alpha_mod);
+	// Alpha mapping
+	float alpha = texel.a * alpha_mod;
+	if (use_alpha_map) {
+		alpha *= texture(alpha_texture, tex_coord).r;
+	}
+
+	frag_color = vec4(frag_rgb, alpha);
 }

src/3d/3d_internal.h

@@ -55,6 +55,7 @@ struct mesh {
 struct material {
 	GLuint color_map;
 	GLuint specular_map;
+	GLuint alpha_map;
 	GLuint light_map;
 	GLuint normal_map;
 	float specular_strength;
@@ -149,6 +150,8 @@ struct RE_renderer {
 	GLint ls_light_dir;
 	GLint ls_light_color;
 	GLint ls_sun_color;
+	GLint use_alpha_map;
+	GLint alpha_texture;
 
 	GLuint billboard_vao;
 	GLuint billboard_attr_buffer;
@@ -358,6 +361,7 @@ struct pol {
 enum pol_texture_type {
 	COLOR_MAP = 1,
 	SPECULAR_MAP = 4,
+	ALPHA_MAP = 6,
 	LIGHT_MAP = 7,
 	NORMAL_MAP = 8,
 	MAX_TEXTURE_TYPE

src/3d/model.c

@@ -99,6 +99,8 @@ static bool init_material(struct material *material, const struct pol_material *
 
 	if (m->textures[SPECULAR_MAP])
 		material->specular_map = load_texture(aar, path, m->textures[SPECULAR_MAP]);
+	if (m->textures[ALPHA_MAP])
+		material->alpha_map = load_texture(aar, path, m->textures[ALPHA_MAP]);
 	if (m->textures[LIGHT_MAP])
 		material->light_map = load_texture(aar, path, m->textures[LIGHT_MAP]);
 	if (m->textures[NORMAL_MAP])
@@ -129,6 +131,8 @@ static void destroy_material(struct material *material)
 		glDeleteTextures(1, &material->color_map);
 	if (material->specular_map)
 		glDeleteTextures(1, &material->specular_map);
+	if (material->alpha_map)
+		glDeleteTextures(1, &material->alpha_map);
 	if (material->light_map)
 		glDeleteTextures(1, &material->light_map);
 	if (material->normal_map)

src/3d/renderer.c

@@ -32,6 +32,7 @@
 enum {
 	COLOR_TEXTURE_UNIT,
 	SPECULAR_TEXTURE_UNIT,
+	ALPHA_TEXTURE_UNIT,
 	LIGHT_TEXTURE_UNIT,
 	NORMAL_TEXTURE_UNIT,
 	SHADOW_TEXTURE_UNIT,
@@ -199,6 +200,8 @@ struct RE_renderer *RE_renderer_new(struct texture *texture)
 	r->ls_light_dir = glGetUniformLocation(r->program, "ls_light_dir");
 	r->ls_light_color = glGetUniformLocation(r->program, "ls_light_color");
 	r->ls_sun_color = glGetUniformLocation(r->program, "ls_sun_color");
+	r->use_alpha_map = glGetUniformLocation(r->program, "use_alpha_map");
+	r->alpha_texture = glGetUniformLocation(r->program, "alpha_texture");
 
 	glGenRenderbuffers(1, &r->depth_buffer);
 	glBindRenderbuffer(GL_RENDERBUFFER, r->depth_buffer);
@@ -339,6 +342,15 @@ static void render_model(struct RE_instance *inst, struct RE_renderer *r)
 			glUniform1i(r->use_normal_map, GL_FALSE);
 		}
 
+		if (material->alpha_map) {
+			glUniform1i(r->use_alpha_map, GL_TRUE);
+			glActiveTexture(GL_TEXTURE0 + ALPHA_TEXTURE_UNIT);
+			glBindTexture(GL_TEXTURE_2D, material->alpha_map);
+			glUniform1i(r->alpha_texture, ALPHA_TEXTURE_UNIT);
+		} else {
+			glUniform1i(r->use_alpha_map, GL_FALSE);
+		}
+
 		glBindVertexArray(mesh->vao);
 		glDrawArrays(GL_TRIANGLES, 0, mesh->nr_vertices);
 		glBindVertexArray(0);
@@ -407,6 +419,7 @@ static void render_billboard(struct RE_instance *inst, struct RE_renderer *r, ma
 	glUniform1i(r->diffuse_type, DIFFUSE_NORMAL);
 	glUniform1i(r->use_normal_map, GL_FALSE);
 	glUniform1i(r->use_shadow_map, GL_FALSE);
+	glUniform1i(r->use_alpha_map, GL_FALSE);
 
 	glActiveTexture(GL_TEXTURE0);
 	glBindTexture(GL_TEXTURE_2D, bt->texture);
@@ -516,6 +529,7 @@ static void render_particle_effect(struct RE_instance *inst, struct RE_renderer
 	glUniform1f(r->rim_exponent, 0.0);
 	glUniform1i(r->use_normal_map, GL_FALSE);
 	glUniform1i(r->use_shadow_map, GL_FALSE);
+	glUniform1i(r->use_alpha_map, GL_FALSE);
 
 	glDepthMask(GL_FALSE);
 
@@ -543,7 +557,7 @@ static void render_particle_effect(struct RE_instance *inst, struct RE_renderer
 			break;
 		}
 	}
-	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ZERO, GL_ONE);
 	glDepthMask(GL_TRUE);
 }
 
@@ -758,7 +772,7 @@ void RE_render(struct sact_sprite *sp)
 	}
 
 	glEnable(GL_BLEND);
-	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ZERO, GL_ONE);
 
 	setup_lights(plugin);
 
@@ -791,6 +805,7 @@ void RE_render(struct sact_sprite *sp)
 	glUseProgram(0);
 	glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 0);
 	gfx_reset_framebuffer(GL_DRAW_FRAMEBUFFER, fbo);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 }
 
 struct height_detector {