unity渲染带颜色的文字
从api inspector可以看到使用的是vertex array 111
glVertexAttribPointer
void glVertexAttribPointer(
GLuint index, // 要修改的顶点属性的索引，也就是vertex shader里面的attribute location
GLint size, // 顶点分量，是vec/vec2/vec3/vec4
GLenum type, // 数据类型，最常用的是GL_UNSIGNED_BYTE、GL_FLOAT
GLboolean normalized, // 归一化
GLsizei stride, // 一个顶点数据的字节大小
const void * pointer// 如果缓冲对象绑定到GL_ARRAY_BUFFER，则pointer应该是一个偏移量，否则它可以是一个指针。
);
举例
V3F_C4B_T2F _verts[VBO_SIZE];
#define kQuadSize sizeof(_verts[0])
// vertices
glVertexAttribPointer(
GLProgram::VERTEX_ATTRIB_POSITION, // positon attribute location
3, // xyz是有3个float分量
GL_FLOAT, // float类型
GL_FALSE,
kQuadSize, // 一个顶点的数据大小
(GLvoid*) offsetof(V3F_C4B_T2F, vertices)// 位置顶点数据在一个顶点数据中的偏移量
);
// colors
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, 4, GL_UNSIGNED_BYTE, GL_TRUE, kQuadSize, (GLvoid*) offsetof(V3F_C4B_T2F, colors));
// tex coords
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_TEX_COORD, 2, GL_FLOAT, GL_FALSE, kQuadSize, (GLvoid*) offsetof(V3F_C4B_T2F, texCoords));
有了以上基础知识，看下unity的细节
glVertexAttribPointer(0, 3, GL_FLOAT, False, 32, 0)
glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, True, 32, 12)
glVertexAttribPointer(2, 4, GL_FLOAT, False, 32, 16)
反推下结构：
struct UnityVertexData{
Vec3F postion,//float 3
RGBA color;// unsigned char 4
Vec4F uv;// float 4
}
一个顶点的大小为32 = 3*4 + 4*1 + 4*4
推导出这个结构后，我们看下Buffer填充的数据，renderdoc是以字节为单位，16进制进行显示的，大致结构拆分如下，一共4个顶点数据
这里面应该有字节大端小端的问题，展示出来的十六进制数值有点庞大，我尝试换了个颜色绿色：0x00FF00FF，发现了应该是倒着读
对应的unity shader
从renderdoc里面拔出来的，不一定准确
#version 450
#extension GL_ARB_explicit_attrib_location : require
#ifdef GL_ARB_shader_bit_encoding
#extension GL_ARB_shader_bit_encoding : enable
#endif
#define HLSLCC_ENABLE_UNIFORM_BUFFERS 1
#if HLSLCC_ENABLE_UNIFORM_BUFFERS
#define UNITY_UNIFORM
#else
#define UNITY_UNIFORM uniform
#endif
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
uniform vec4 _TextureSampleAdd;
UNITY_LOCATION(0) uniform sampler2D _MainTex;
in vec4 vs_COLOR0;
in vec2 vs_TEXCOORD0;
layout(location = 0) out vec4 SV_Target0;
vec4 u_xlat0;
void main()
{
u_xlat0 = texture(_MainTex, vs_TEXCOORD0.xy);
u_xlat0 = u_xlat0 + _TextureSampleAdd;
u_xlat0 = u_xlat0 * vs_COLOR0;
SV_Target0.xyz = u_xlat0.www * u_xlat0.xyz;
SV_Target0.w = u_xlat0.w;
return;
}
#version 450
#extension GL_ARB_explicit_attrib_location : require
#ifdef GL_ARB_shader_bit_encoding
#extension GL_ARB_shader_bit_encoding : enable
#endif
#define HLSLCC_ENABLE_UNIFORM_BUFFERS 1
#if HLSLCC_ENABLE_UNIFORM_BUFFERS
#define UNITY_UNIFORM
#else
#define UNITY_UNIFORM uniform
#endif
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
uniform vec4 _ScreenParams;
uniform vec4 hlslcc_mtx4x4unity_ObjectToWorld[4];
uniform vec4 hlslcc_mtx4x4glstate_matrix_projection[4];
uniform vec4 hlslcc_mtx4x4unity_MatrixVP[4];
uniform vec4 _Color;
uniform vec4 _ClipRect;
uniform vec4 _MainTex_ST;
uniform float _UIMaskSoftnessX;
uniform float _UIMaskSoftnessY;
in vec4 in_POSITION0;
in vec4 in_COLOR0;
in vec2 in_TEXCOORD0;
out vec4 vs_COLOR0;
out vec2 vs_TEXCOORD0;
out vec4 vs_TEXCOORD1;
out vec4 vs_TEXCOORD2;
vec4 u_xlat0;
vec4 u_xlat1;
void main()
{
u_xlat0 = in_POSITION0.yyyy * hlslcc_mtx4x4unity_ObjectToWorld[1];
u_xlat0 = hlslcc_mtx4x4unity_ObjectToWorld[0] * in_POSITION0.xxxx + u_xlat0;
u_xlat0 = hlslcc_mtx4x4unity_ObjectToWorld[2] * in_POSITION0.zzzz + u_xlat0;
u_xlat0 = u_xlat0 + hlslcc_mtx4x4unity_ObjectToWorld[3];
u_xlat1 = u_xlat0.yyyy * hlslcc_mtx4x4unity_MatrixVP[1];
u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[0] * u_xlat0.xxxx + u_xlat1;
u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[2] * u_xlat0.zzzz + u_xlat1;
u_xlat0 = hlslcc_mtx4x4unity_MatrixVP[3] * u_xlat0.wwww + u_xlat1;
gl_Position = u_xlat0;
vs_COLOR0 = in_COLOR0 * _Color;
vs_TEXCOORD0.xy = in_TEXCOORD0.xy * _MainTex_ST.xy + _MainTex_ST.zw;
vs_TEXCOORD1 = in_POSITION0;
u_xlat0.xy = _ScreenParams.yy * hlslcc_mtx4x4glstate_matrix_projection[1].xy;
u_xlat0.xy = hlslcc_mtx4x4glstate_matrix_projection[0].xy * _ScreenParams.xx + u_xlat0.xy;
u_xlat0.xy = u_xlat0.ww / abs(u_xlat0.xy);
u_xlat0.xy = vec2(_UIMaskSoftnessX, _UIMaskSoftnessY) * vec2(0.25, 0.25) + abs(u_xlat0.xy);
vs_TEXCOORD2.zw = vec2(0.25, 0.25) / u_xlat0.xy;
u_xlat0 = max(_ClipRect, vec4(-2e+10, -2e+10, -2e+10, -2e+10));
u_xlat0 = min(u_xlat0, vec4(2e+10, 2e+10, 2e+10, 2e+10));
u_xlat0.xy = in_POSITION0.xy * vec2(2.0, 2.0) + (-u_xlat0.xy);
vs_TEXCOORD2.xy = (-u_xlat0.zw) + u_xlat0.xy;
return;
}
