alpha blending

4 files changed, 153 insertions, 16 deletions

diff --git a/pipeline.cpp b/pipeline.cpp
index 015a5dd..a3ea553 100644
--- a/pipeline.cpp
+++ b/pipeline.cpp
@@ -165,6 +165,38 @@ void Pipeline_Builder::depth(bool test, bool write, Depth_Mode mode) {
 	pip->depth_mode = mode;
 }
 
+void Pipeline_Builder::blend(
+	Blend_Mode mode,
+	Blend_Factor src,
+	Blend_Factor dst
+) {
+	blend(
+		mode,
+		src,
+		dst,
+		mode,
+		src,
+		dst
+	);
+}
+
+void Pipeline_Builder::blend(
+	Blend_Mode mode_col,
+	Blend_Factor src_col,
+	Blend_Factor dst_col,
+	Blend_Mode mode_alpha,
+	Blend_Factor src_alpha,
+	Blend_Factor dst_alpha
+) {
+	pip->blend_enable = true;
+	pip->blend_mode = mode_col;
+	pip->blend_src = src_col;
+	pip->blend_dst = dst_col;
+	pip->blend_mode_alpha = mode_alpha;
+	pip->blend_src_alpha = src_alpha;
+	pip->blend_dst_alpha = dst_alpha;
+}
+
 void Pipeline_Builder::shader(Shader_Id s) {
 	pip->shader = s;
 }
@@ -226,6 +258,13 @@ Pipeline& Pipeline_Builder::build() {
 	h(pip->pipeline_hash, pip->depth_test);
 	h(pip->pipeline_hash, pip->depth_write);
 	h(pip->pipeline_hash, pip->depth_mode);
+	h(pip->pipeline_hash, pip->blend_enable);
+	h(pip->pipeline_hash, pip->blend_mode);
+	h(pip->pipeline_hash, pip->blend_mode_alpha);
+	h(pip->pipeline_hash, pip->blend_src);
+	h(pip->pipeline_hash, pip->blend_dst);
+	h(pip->pipeline_hash, pip->blend_src_alpha);
+	h(pip->pipeline_hash, pip->blend_dst_alpha);
 	{
 		int i, e = pip->descriptor_count;
 		pip->descriptor_resource_hash = fnv1a64(0, 0);
diff --git a/ui.cpp b/ui.cpp
index 8264576..f6caedd 100644
--- a/ui.cpp
+++ b/ui.cpp
@@ -272,6 +272,11 @@ void UI::render(Arena* s, Texture_Id target) {
 	pb.begin();
 	pb.shader(shader);
 	pb.vertex_format(vertex_format);
+	pb.blend(
+		Blend_Mode::add,
+		Blend_Factor::src_alpha,
+		Blend_Factor::inv_src_colour
+	);
 	pb.cbuffer(shader_info.config_binding, config_buf);
 	pb.texture(shader_info.atlas_binding, atlas, sampler);
 	Pipeline& pip = pb.build();
diff --git a/video.cpp b/video.cpp
index 1d71034..586a78e 100644
--- a/video.cpp
+++ b/video.cpp
@@ -277,6 +277,35 @@ static VkFormat get_vk_format(Texture_Format fmt) {
 	return VK_FORMAT_UNDEFINED;
 }
 
+static VkBlendFactor get_vk_blend_factor(Blend_Factor mode) {
+	switch (mode) {
+		case Blend_Factor::zero:           return VK_BLEND_FACTOR_ZERO;
+		case Blend_Factor::one:            return VK_BLEND_FACTOR_ONE;
+		case Blend_Factor::src_colour:     return VK_BLEND_FACTOR_SRC_COLOR;
+		case Blend_Factor::inv_src_colour: return VK_BLEND_FACTOR_ONE_MINUS_SRC_COLOR;
+		case Blend_Factor::dst_colour:     return VK_BLEND_FACTOR_DST_COLOR;
+		case Blend_Factor::inv_dst_colour: return VK_BLEND_FACTOR_ONE_MINUS_DST_COLOR;
+		case Blend_Factor::src_alpha:      return VK_BLEND_FACTOR_SRC_ALPHA;
+		case Blend_Factor::inv_src_alpha:  return VK_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA;
+		case Blend_Factor::dst_alpha:      return VK_BLEND_FACTOR_DST_ALPHA;
+		case Blend_Factor::inv_dst_alpha:  return VK_BLEND_FACTOR_ONE_MINUS_DST_ALPHA;
+	}
+	assert(0);
+	return VK_BLEND_FACTOR_ONE;
+}
+
+static VkBlendOp get_vk_blend_op(Blend_Mode mode) {
+	switch (mode) {
+		case Blend_Mode::add:              return VK_BLEND_OP_ADD;
+		case Blend_Mode::subtract:         return VK_BLEND_OP_SUBTRACT;
+		case Blend_Mode::reverse_subtract: return VK_BLEND_OP_SUBTRACT;
+		case Blend_Mode::min:              return VK_BLEND_OP_MIN;
+		case Blend_Mode::max:              return VK_BLEND_OP_MAX;
+	}
+	assert(0);
+	return VK_BLEND_OP_ADD;
+}
+
 static VkImageUsageFlags get_texture_usage(int flags) {
 	VkImageUsageFlags f = 0;
 	if (flags & Texture_Flags::sampleable)
@@ -734,6 +763,7 @@ struct Pipeline_Vk {
 		Arena& scope,
 		Device_Vk* dev,
 		VkGraphicsPipelineCreateInfo& info,
+		const Render_Pass& rp,
 		const Pipeline& desc
 	);
 	void init_layout(
@@ -2621,6 +2651,7 @@ void Pipeline_Vk::init_blending(
 	Arena& scope,
 	Device_Vk* dev,
 	VkGraphicsPipelineCreateInfo& info,
+	const Render_Pass& rp,
 	const Pipeline& desc
 ) {
 	VkPipelineColorBlendStateCreateInfo& bi = 
@@ -2628,26 +2659,45 @@ void Pipeline_Vk::init_blending(
 			&scope,
 			sizeof bi
 		);
-	VkPipelineColorBlendAttachmentState& abs =
-		*(VkPipelineColorBlendAttachmentState*)arena_alloc(
-			&scope,
-			sizeof abs
-		);
+	VkPipelineColorBlendAttachmentState* abs;
 	(void)dev;
 	(void)desc;
 	zero(&bi, sizeof bi);
-	zero(&abs, sizeof abs);
-	abs.colorWriteMask = 
-		VK_COLOR_COMPONENT_R_BIT |
-		VK_COLOR_COMPONENT_G_BIT |
-		VK_COLOR_COMPONENT_B_BIT |
-		VK_COLOR_COMPONENT_A_BIT;
-	abs.blendEnable = VK_FALSE;
+	if (rp.colour_count) {
+		int i, c = rp.colour_count;
+		abs =
+		(VkPipelineColorBlendAttachmentState*)arena_alloc(
+			&scope,
+			sizeof abs * c
+		);
+		zero(abs, sizeof *abs);
+		for (i = 0; i < c; i++) {
+			auto& ab = abs[i];
+			ab.colorWriteMask =
+				VK_COLOR_COMPONENT_R_BIT |
+				VK_COLOR_COMPONENT_G_BIT |
+				VK_COLOR_COMPONENT_B_BIT |
+				VK_COLOR_COMPONENT_A_BIT;
+			ab.blendEnable = desc.blend_enable;
+			if (desc.blend_enable) {
+				ab.srcColorBlendFactor =
+					get_vk_blend_factor(desc.blend_src);
+				ab.dstColorBlendFactor =
+					get_vk_blend_factor(desc.blend_dst);
+				ab.srcAlphaBlendFactor =
+					get_vk_blend_factor(desc.blend_src_alpha);
+				ab.dstAlphaBlendFactor =
+					get_vk_blend_factor(desc.blend_dst_alpha);
+				ab.colorBlendOp = get_vk_blend_op(desc.blend_mode);
+				ab.alphaBlendOp = get_vk_blend_op(desc.blend_mode_alpha);
+			}
+		}
+	}
 	bi.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
 	bi.flags = 0;
 	bi.logicOpEnable = VK_FALSE;
-	bi.attachmentCount = 1;
-	bi.pAttachments = &abs;
+	bi.attachmentCount = rp.colour_count;
+	bi.pAttachments = abs;
 	info.pColorBlendState = &bi;
 }
 
@@ -2764,7 +2814,7 @@ void Pipeline_Vk::init(Device_Vk* dev, const Pso_Key& key) {
 	init_rasterisation(scope, dev, info, desc);
 	init_msaa(scope, dev, info, desc);
 	init_depthstencil(scope, dev, info, desc);
-	init_blending(scope, dev, info, desc);
+	init_blending(scope, dev, info, key.rpo.rpo, desc);
 	info.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
 	info.flags = 0;
 	info.renderPass = dev->get_rpo(key.rpo).rpo;
diff --git a/video.hpp b/video.hpp
index 9a5dbe3..9b64543 100644
--- a/video.hpp
+++ b/video.hpp
@@ -83,13 +83,40 @@ enum class Depth_Mode {
 	never
 };
 
+enum class Blend_Factor {
+	zero,
+	one,
+	src_colour,
+	inv_src_colour,
+	dst_colour,
+	inv_dst_colour,
+	src_alpha,
+	inv_src_alpha,
+	dst_alpha,
+	inv_dst_alpha
+};
+
+enum class Blend_Mode {
+	add,
+	subtract,
+	reverse_subtract,
+	min,
+	max
+};
+
+
 struct Pipeline {
 	uint64_t pipeline_hash;
 	uint64_t descriptor_resource_hash;
 	int viewport[4];
 	int scissor[4];
 	bool depth_test, depth_write;
+	bool blend_enable;
 	Depth_Mode depth_mode;
+	Blend_Factor blend_src, blend_dst;
+	Blend_Mode blend_mode;
+	Blend_Factor blend_src_alpha, blend_dst_alpha;
+	Blend_Mode blend_mode_alpha;
 	Vertex_Format_Id vertex_format;
 	Shader_Id shader;
 	Descriptor descriptors[pipeline_max_descriptors];
@@ -109,7 +136,14 @@ struct Pipeline {
 			scissor[3] == other.scissor[3] &&
 			depth_test == other.depth_test &&
 			depth_write == other.depth_write &&
-			depth_mode == other.depth_mode;
+			depth_mode == other.depth_mode &&
+			blend_enable == other.blend_enable &&
+			blend_src == other.blend_src &&
+			blend_dst == other.blend_dst &&
+			blend_src_alpha == other.blend_src_alpha &&
+			blend_dst_alpha == other.blend_dst_alpha &&
+			blend_mode == other.blend_mode &&
+			blend_mode_alpha == other.blend_mode_alpha;
 	}
 
 	bool desc_layout_eq(const Pipeline& other) const {
@@ -257,6 +291,15 @@ struct Pipeline_Builder {
 	void viewport(float x, float y, float w, float h);
 	void scissor(float x, float y, float w, float h);
 	void depth(bool test, bool write, Depth_Mode mode);
+	void blend(Blend_Mode mode, Blend_Factor src, Blend_Factor dst);
+	void blend(
+		Blend_Mode mode_col,
+		Blend_Factor src_col,
+		Blend_Factor dst_col,
+		Blend_Mode mode_alpha,
+		Blend_Factor src_alpha,
+		Blend_Factor dst_alpha
+	);
 	void shader(Shader_Id s);
 	void vertex_format(Vertex_Format_Id vf);
 	void texture(int binding, Texture_Id t, Sampler_Id s);