Shader

In Astro shaders provide a way to manipulate how textures and sprites are rendered. You may load shaders in a vertex/fragment pair and then tell the renderer to use your shader instead of its default shader with shader=. The default shader just outputs the texture/sprite with the colour mod applied.

load()
data

load

construct load(vertex_file, frag_file, buffer_size)

Parameters

vertex_file -> String Filename of the SPIR-V compiled vertex shader.
frag_file -> String Filename of the SPIR-V compiled fragment shader.
buffer_size -> Num Size of the uniform buffer in your shaders in bytes. Must be a multiple of 4.

Loads a new shader from provided SPIR-V compiled files. How you make these shaders is very strict.

The vertex shader must use this as a header:

layout(set = 0, binding = 0) uniform UniformBufferObject {
    mat4 viewproj;
} ubo;

layout(push_constant) uniform PushBuffer {
    mat4 model;
    vec4 colourMod;
    vec4 textureCoords;
} pushBuffer;

layout(location = 1) out vec2 fragTexCoord;

vec2 vertices[] = {
    vec2(0.0f, 0.0f),
    vec2(1.0f, 0.0f),
    vec2(1.0f, 1.0f),
    vec2(1.0f, 1.0f),
    vec2(0.0f, 1.0f),
    vec2(0.0f, 0.0f),
};

vec2 texCoords[] = {
    vec2(0.0f, 0.0f),
    vec2(1.0f, 0.0f),
    vec2(1.0f, 1.0f),
    vec2(1.0f, 1.0f),
    vec2(0.0f, 1.0f),
    vec2(0.0f, 0.0f),
};

out gl_PerVertex {
    vec4 gl_Position;
};

You may notice that the renderer does not pass vertex coordinates for texture and instead just embeds them in the shader. This means that the fragment shader applies UV changes internally. The fragment shader must have this header:

layout(set = 1, binding = 1) uniform sampler texSampler;
layout(set = 2, binding = 2) uniform texture2D tex;

layout(push_constant) uniform PushBuffer {
    mat4 model;
    vec4 colourMod;
    vec4 textureCoords;
} pushBuffer;

layout(location = 1) in vec2 fragTexCoord;

layout(location = 0) out vec4 outColor;

If buffer_size is not 0, you must also add the following to both files:

layout(set = 3, binding = 3) uniform UserData {
    // your data here...
} userData;

This is how your shaders will access data from your program.

Astro uses Vulkan2D internally, so if you wish to see the default shaders, fragment shader, and vertex shader.

data=

Write Only: data=(data)

Variable Type: Buffer - Buffer containing the uniform buffer’s data.

Sets the uniform buffer’s data. This must be used at least once if the buffer_size size set in load was non-zero. data.size must be at least that specified amount. Each time the shader is used, this data will be provided to the shader until this is updated. You may update shader data as many times as you wish per frame.