vulkan中vertex buffer的用法

2019-11-09 17:48:46

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-Vulkan的資源(buffer或者image)都用descriptor表示，vertex buffer也是以descriptor的形式來分配和使用的下面講的是如果使用vertex buffer來向shader傳遞頂點數據1.準備vertex數據 const float vb[3][5] = { /* position texcoord */ { -1.0f, -1.0f, 0.25f, 0.0f, 0.0f }, { 1.0f, -1.0f, 0.25f, 1.0f, 0.0f }, { 0.0f, 1.0f, 1.0f, 0.5f, 1.0f }, };2.調用vkCreateBuffer創建VkBuffer(buf)，然后用vkAllocateMemory來分配device內存(men)3.vkMapMemory將device內存map到cpu端(data)4.memcpy(data, vb, sizeof(vb));5.調用vkBindBufferMemory(device,buf,mem)將device內存和vkbuffer綁定6.創建vi，VkPipelineVertexInputStateCreateInfo vi demo->vertices.vi.vertexAttributeDescriptionCount = 2;

demo->vertices.vi.pVertexAttributeDescriptions = demo->vertices.vi_attrs;//vi_attrs是關鍵

demo->vertices.vi_attrs[0].binding = VERTEX_BUFFER_BIND_ID; demo->vertices.vi_attrs[0].location = 0; demo->vertices.vi_attrs[0].format = VK_FORMAT_R32G32B32_SFLOAT; demo->vertices.vi_attrs[0].offset = 0; demo->vertices.vi_attrs[1].binding = VERTEX_BUFFER_BIND_ID; demo->vertices.vi_attrs[1].location = 1; demo->vertices.vi_attrs[1].format = VK_FORMAT_R32G32_SFLOAT; demo->vertices.vi_attrs[1].offset = sizeof(float) * 3;7.在create pipeline的時候傳入剛創建的vi：pipeline.pVertexInputState = &vi;8.build cmd的時候，bind之前創建的vertex buffer vkCmdBindVertexBuffers(demo->draw_cmd, VERTEX_BUFFER_BIND_ID, 1,&demo->vertices.buf, offsets); vkCmdDraw(demo->draw_cmd, 3, 1, 0, 0); vkCmdEndRenderPass(demo->draw_cmd);9.在shader中使用vertex buffer vs #version 400 #extension GL_ARB_separate_shader_objects : enable #extension GL_ARB_shading_language_420pack : enable layout (location = 0) in vec4 pos; layout (location = 1) in vec2 attr; layout (location = 0) out vec2 texcoord; void main() { texcoord = attr; gl_Position = pos; } fs #version 400 #extension GL_ARB_separate_shader_objects : enable #extension GL_ARB_shading_language_420pack : enable layout (binding = 0) uniform sampler2D tex; layout (location = 0) in vec2 texcoord; layout (location = 0) out vec4 uFragColor; void main() { uFragColor = texture(tex, texcoord); } comment：layout(location = attribute index) in vec3 position;

跟glBindAttribLocation的功能類似，設置position使用哪個屬性:

static const GLfloat verts[3][2] = { { -0.5, -0.5 }, { 0.5, -0.5 }, { 0, 0.5 } };"attribute vec4 pos;/n"//in shaderglBindAttribLocation(PRogram, window->gl.pos, "pos");glVertexAttribPointer(window->gl.pos, 2, GL_FLOAT, GL_FALSE, 0, verts);glEnableVertexAttribArray(window->gl.pos);glDrawArrays()

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