sdl2_frt/src/render/metal/SDL_shaders_metal.metal

#include <metal_texture>
#include <metal_matrix>

using namespace metal;

struct SolidVertexOutput
{
    float4 position [[position]];
    float pointSize [[point_size]];
};

vertex SolidVertexOutput SDL_Solid_vertex(const device float2 *position [[buffer(0)]],
                                          constant float4x4 &projection [[buffer(2)]],
                                          constant float4x4 &transform [[buffer(3)]],
                                          uint vid [[vertex_id]])
{
    SolidVertexOutput v;
    v.position = (projection * transform) * float4(position[vid], 0.0f, 1.0f);
    v.pointSize = 0.5f;
    return v;
}

fragment float4 SDL_Solid_fragment(constant float4 &col [[buffer(0)]])
{
    return col;
}

struct CopyVertexOutput
{
    float4 position [[position]];
    float2 texcoord;
};

vertex CopyVertexOutput SDL_Copy_vertex(const device float2 *position [[buffer(0)]],
                                        const device float2 *texcoords [[buffer(1)]],
                                        constant float4x4 &projection [[buffer(2)]],
                                        constant float4x4 &transform [[buffer(3)]],
                                        uint vid [[vertex_id]])
{
    CopyVertexOutput v;
    v.position = (projection * transform) * float4(position[vid], 0.0f, 1.0f);
    v.texcoord = texcoords[vid];
    return v;
}

fragment float4 SDL_Copy_fragment(CopyVertexOutput vert [[stage_in]],
                                  constant float4 &col [[buffer(0)]],
                                  texture2d<float> tex [[texture(0)]],
                                  sampler s [[sampler(0)]])
{
    return tex.sample(s, vert.texcoord) * col;
}