alpha blending

1 files changed, 65 insertions, 15 deletions

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;