I'm trying to create a vertex shader in Scenekit. The shader is successfully added to the geometry of the SCNNode, however it displays purple because I get an error. I added the shaders to the geometry using SCNShaderModifiers and know that they are successfully found and attached.
The exact error messages I recieved is:
2020-08-31 21:26:53.977977-0700 Azure[69834:3664712] [SceneKit] Error: FATAL ERROR : failed compiling shader:
Error Domain=MTLLibraryErrorDomain Code=3 "Compilation failed:
program_source:2901:97: error: function definition is not allowed here
float2 wavedx(float2 position, float2 direction, float speed, float frequency, float timeshift) {
^
program_source:2908:49: error: function definition is not allowed here
float getwaves(float2 position, int iterations) {
^
" UserInfo={NSLocalizedDescription=Compilation failed:
program_source:2901:97: error: function definition is not allowed here
float2 wavedx(float2 position, float2 direction, float speed, float frequency, float timeshift) {
^
program_source:2908:49: error: function definition is not allowed here
float getwaves(float2 position, int iterations) {
^
}
However, when I am not using methods, the shader works perfectly. To test this I used a regular sinusoidal shader. The following example worked:
uniform float Amplitude = 0.1;
_geometry.position.z += sin(u_time + _geometry.position.x);
The code I was trying to get to work was this, which has functions:
float Time = u_time;
float DRAG_MULT = 0.048;
vec2 wavedx(vec2 position, vec2 direction, float speed, float frequency, float timeshift) {
float x = dot(direction, position) * frequency + timeshift * speed;
float wave = exp(sin(x) - 1.0);
float dx = wave * cos(x);
return vec2(wave, -dx);
}
float getwaves(vec2 position, int iterations) {
float iter = 0.0;
float phase = 6.0;
float speed = 2.0;
float weight = 1.0;
float w = 0.0;
float ws = 0.0;
for(int i = 0; i < iterations; i++){
vec2 p = vec2(sin(iter), cos(iter));
vec2 res = wavedx(position, p, speed, phase, Time);
position += normalize(p) * res.y * weight * DRAG_MULT;
w += res.x * weight;
iter += 12.0;
ws += weight;
weight = mix(weight, 0.0, 0.2);
phase *= 1.18;
speed *= 1.07;
}
return w / ws;
}
I have no idea what's going wrong here. These are all standalone GLSL snippets. Thanks!
I added the shaders to the geometry using SCNShaderModifiers and know that they are successfully found and attached.
If you use SCNShaderModifiers, you also have to adhere to their documentation:
Custom global functions. If your shader modifier benefits from factoring common code into functions, place their definitions here. If
you include custom functions in your snippet, you must place the
#pragma body directive between your function definitions and the main body of the snippet.
Related
I'm trying to import many transitions from GL Transitions into my video sequencer by converting GLSL to HLSL.
For example, this simple cross fade:
vec4 transition (vec2 uv) {
return mix(
getFromColor(uv),
getToColor(uv),
progress
);
}
is correctly translated in my HLSL code:
#define D2D_INPUT_COUNT 2
#define D2D_INPUT0_SIMPLE
#define D2D_INPUT1_SIMPLE
#define D2D_REQUIRES_SCENE_POSITION // The pixel shader requires the SCENE_POSITION input.
#include "d2d1effecthelpers.hlsli"
cbuffer constants : register(b0)
{
float progress : packoffset(c0.x);
...
}
float4 crossfade(float4 v1,float4 v2)
{
return lerp(v1, v2, progress);
}
D2D_PS_ENTRY(main)
{
float4 v1 = D2DGetInput(0);
float4 v2 = D2DGetInput(1);
return crossfade(v1,v2);
}
The same doesn't work for Wind effect:
// Custom parameters
uniform float size; // = 0.2
float rand (vec2 co) {
return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
}
vec4 transition (vec2 uv) {
float r = rand(vec2(0, uv.y));
float m = smoothstep(0.0, -size, uv.x*(1.0-size) + size*r - (progress * (1.0 + size)));
return mix(
getFromColor(uv),
getToColor(uv),
m
);
}
This time HLSL is this:
float fract(float x)
{
return x - floor(x);
}
float rand(float2 co)
{
return fract(sin(dot(co.xy, float2(12.9898, 78.233))) * 43758.5453);
}
float4 wind(float4 v1, float4 v2,float2 uv)
{
float r = rand(float2(0, uv.y));
p1 = 0.2f;
progress = 0.5f; // hardcoded variables for testing, they will be taken from the buffer
float m = smoothstep(0.0f, -p1, uv.x*(1.0f-p1) + p1*r - (progress * (1.0f + p1)));
return lerp(v1, v2, m);
}
D2D_PS_ENTRY(main)
{
float4 v1 = D2DGetInput(0);
float4 v2 = D2DGetInput(1);
return wind(v1,v2,D2DGetScenePosition().xy);
}
Have I misunderstood the OpenGL's mix and fract and rand stuff? I only get the second image pixels in my HLSL version without mixing.
EDIT: I 've hardcoded size to 0.992 and multiplied progress by 4 in the HLSL. Now it seems to work, do I miss some bounds-related issues? Is the smoothstep function working as expected?
I found it.
It would need in main entry the usage of D2DGetInputCoordinate instead of D2DGetScenePosition
After doing that, the transitions run fine.
I have double 'radius' = 2.0E-45, when i set it to ~2.0E-46 calculation collapse resulting in white screen. So seems like issue is overflow. I wrote the same algorithm but using nubma cuda and f64 (double precision) 'radius'. And everything works fine. I am using f32 texture buffer for 'depth_array' (there is no float64 dtype for this), but numba implementation works fine with f32, and opengl implementation also works fine until 'radius' bigger than ~2.0E-46. Why numba implementation works, while opengl not? I want to stick with opengl. Is there any possibility to fix it?
I only put in parts that use the 'radius'. All other variables are double type. (code is messy and just a scratch)
#version 150
#extension GL_ARB_gpu_shader_fp64 : enable
double radius = 2.0E-45;
...
dvec2 pixel = dvec2(gl_FragCoord.xy) + dvec2(-0.5+(double(x)+0.5)/double(AA),-0.5+(double(y)+0.5)/double(AA));
dvec2 c = pixel/dvec2(width, height) * dvec2(radius, radius) + dvec2(-radius/2, -radius/2);
color.rgb += sample(c);
...
vec3 sample(dvec2 dn)
{
vec3 color = vec3(0.0,0.0,0.0);
dvec2 d0 = dn;
double zn_size = 0.0;
int i = 0;
while (i < depth)
{
int x = i % depth;
dvec2 value = dvec2(texelFetch(depth_array, x).rg);
dn = complex_mul(dn, value + dn);
dn = dn + d0;
i++;
x = i % depth;
value = dvec2(texelFetch(depth_array, x).rg);
dvec2 zn = value * 0.5 + dn;
zn_size = dot(zn, zn);
if (zn_size > r)
{
double fraciter = (zn_size-r)/(r2-r);
double iter = double(i) - fraciter;
double m = sqrt(iter)*mul*2.0;
color = sin(vec3(.1, .15, .2)*float(m)*0.5)*.5+0.5;
break;
}
}
return color;
}
In GLSL, the literal value 2.0E-45 has the type float. That means the value will be squashed into the valid range of a float before it gets assigned to a value.
If you want a literal to be a double, then it needs to use the proper suffix: 2.0E-45lf.
I have the a webgl blur shader:
precision mediump float;
precision mediump int;
uniform sampler2D u_image;
uniform float blur;
uniform int u_horizontalpass; // 0 or 1 to indicate vertical or horizontal pass
uniform float sigma; // The sigma value for the gaussian function: higher value means more blur
// A good value for 9x9 is around 3 to 5
// A good value for 7x7 is around 2.5 to 4
// A good value for 5x5 is around 2 to 3.5
// ... play around with this based on what you need :)
varying vec4 v_texCoord;
const vec2 texOffset = vec2(1.0, 1.0);
// uniform vec2 texOffset;
const float PI = 3.14159265;
void main() {
vec2 p = v_texCoord.st;
float numBlurPixelsPerSide = blur / 2.0;
// Incremental Gaussian Coefficent Calculation (See GPU Gems 3 pp. 877 - 889)
vec3 incrementalGaussian;
incrementalGaussian.x = 1.0 / (sqrt(2.0 * PI) * sigma);
incrementalGaussian.y = exp(-0.5 / (sigma * sigma));
incrementalGaussian.z = incrementalGaussian.y * incrementalGaussian.y;
vec4 avgValue = vec4(0.0, 0.0, 0.0, 0.0);
float coefficientSum = 0.0;
// Take the central sample first...
avgValue += texture2D(u_image, p) * incrementalGaussian.x;
coefficientSum += incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
// Go through the remaining 8 vertical samples (4 on each side of the center)
for (float i = 1.0; i <= numBlurPixelsPerSide; i += 1.0) {
avgValue += texture2D(u_image, p - i * texOffset) * incrementalGaussian.x;
avgValue += texture2D(u_image, p + i * texOffset) * incrementalGaussian.x;
coefficientSum += 2.0 * incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
}
gl_FragColor = avgValue / coefficientSum;
}
When I build, I get the following error message:
webgl-renderer.js?2eb3:137 Uncaught could not compile shader:ERROR:
0:38: 'i' : Loop index cannot be compared with non-constant expression
I have also tried to use just the uniform float blur to compare i to. Is there any way to fix this?
The problem is further detailed here: https://www.khronos.org/webgl/public-mailing-list/archives/1012/msg00063.php
The solution that I've found looking around is to only use a constant expression when comparing a loop var. This doesn't fit with what I need to do which is vary how many times I'm looping based on the blur radius.
Any thoughts on this?
This happens because on some hardware, GLSL loops are un-rolled into native GPU instructions. This means there needs to be a hard upper limit to the number of passes through the for loop, that governs how many copies of the loop's inner code will be generated. If you replace numBlurPixelsPerSide with a const float or even a #define directive, and the shader compiler can then determine the number of passes at compile time, and generate the code accordingly. But with a uniform there, the upper limit is not known at compile time.
There's an interesting wrinkle in this rule: You're allowed to break or call an early return out of a for loop, even though the max iterations must be discernible at compile time. For example, consider this tiny Mandelbrot shader. This is hardly the prettiest fractal on GLSL Sandbox, but I chose it for its small size:
precision mediump float;
uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;
varying vec2 surfacePosition;
const float max_its = 100.;
float mandelbrot(vec2 z){
vec2 c = z;
for(float i=0.;i<max_its;i++){ // for loop is here.
if(dot(z,z)>4.) return i; // conditional early return here.
z = vec2(z.x*z.x-z.y*z.y,2.*z.x*z.y)+c;
}
return max_its;
}
void main( void ) {
vec2 p = surfacePosition;
gl_FragColor = vec4(mandelbrot(p)/max_its);
}
In this example, max_its is a const so the compiler knows the upper limit and can un-roll this loop if it needs to. Inside the loop, a return statement offers a way to leave the loop early for pixels that are outside of the Mandelbrot set.
You still don't want to set the max iterations too high, as this can produce a lot of GPU instructions and possibly hurt performance.
Try something like this:
const float MAX_ITERATIONS = 100.0;
// Go through the remaining 8 vertical samples (4 on each side of the center)
for (float i = 1.0; i <= MAX_ITERATIONS; i += 1.0) {
if (i >= numBlurPixelsPerSide){break;}
avgValue += texture2D(u_image, p - i * texOffset) * incrementalGaussian.x;
avgValue += texture2D(u_image, p + i * texOffset) * incrementalGaussian.x;
coefficientSum += 2.0 * incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
}
Sometimes you can use my very simple solving of issue.
My fragment of the shader source code:
const int cloudPointsWidth = %s;
for ( int i = 0; i < cloudPointsWidth; i++ ) {
//TO DO something
}
You can see '%' : syntax error above. But I am replace %s to a number in my javascript code before use my shader. For example:
vertexCode = vertexCode.replace( '%s', 10 );
vertexCode is my shader source code.
Everytime if I want to change cloudPointsWidth, I am destroying my old shader and creating new shader with new cloudPointsWidth .
Hope sometimes my solving can to help you.
You can just do a for loop with large constant number and use a break.
for(int i = 0; i < 1000000; ++i)
{
// your code here
if(i >= n){
break;
}
}
I've had similar problem with image downsampling shader. The code is basically the same:
for (int dx = -2 * SCALE_FACTOR; dx < 2 * SCALE_FACTOR; dx += 2) {
for (int dy = -2 * SCALE_FACTOR; dy < 2 * SCALE_FACTOR; dy += 2) {
/* accumulate fragment's color */
}
}
What I've ended up doing is using preprocessor and creating separate shader programs for every SCALE_FACTOR used (luckily, only 4 was needed). To achieve that, a small helper function was implemented to add #define ... statements to shader code:
function insertDefines (shaderCode, defines) {
var defineString = '';
for (var define in defines) {
if (defines.hasOwnProperty(define)) {
defineString +=
'#define ' + define + ' ' + defines[define] + '\n';
}
}
var versionIdx = shaderCode.indexOf('#version');
if (versionIdx == -1) {
return defineString + shaderCode;
}
var nextLineIdx = shaderCode.indexOf('\n', versionIdx) + 1;
return shaderCode.slice(0, nextLineIdx) +
defineString +
shaderCode.slice(nextLineIdx);
}
The implementation is a bit tricky because if the code already has #version preprocessor statement in it, all other statements have to follow it.
Then I've added a check for SCALE_FACROR being defined:
#ifndef SCALE_FACTOR
# error SCALE_FACTOR is undefined
#endif
And in my javascript code I've done something like this:
var SCALE_FACTORS = [4, 8, 16, 32],
shaderCode, // the code of my shader
shaderPrograms = SCALE_FACTORS.map(function (factor) {
var codeWithDefines = insertDefines(shaderCode, { SCALE_FACTOR: factor });
/* compile shaders, link program, return */
});
I use opengl es3 on android and solve this problem by using extension above the beginning of program like this:
#extension GL_EXT_gpu_shader5 : require
I don't know whether it work on webGL, but you can try it.
Hope it can help.
You can also use template litterals to set the length of the loop
onBeforeCompile(shader) {
const array = [1,2,3,4,5];
shader.uniforms.myArray = { value: array };
let token = "#include <begin_vertex>";
const insert = `
uniform float myArray[${array.length}];
for ( int i = 0; i < ${array.length}; i++ ) {
float test = myArray[ i ];
}
`;
shader.vertexShader = shader.vertexShader.replace(token, token + insert);
}
I have the a webgl blur shader:
precision mediump float;
precision mediump int;
uniform sampler2D u_image;
uniform float blur;
uniform int u_horizontalpass; // 0 or 1 to indicate vertical or horizontal pass
uniform float sigma; // The sigma value for the gaussian function: higher value means more blur
// A good value for 9x9 is around 3 to 5
// A good value for 7x7 is around 2.5 to 4
// A good value for 5x5 is around 2 to 3.5
// ... play around with this based on what you need :)
varying vec4 v_texCoord;
const vec2 texOffset = vec2(1.0, 1.0);
// uniform vec2 texOffset;
const float PI = 3.14159265;
void main() {
vec2 p = v_texCoord.st;
float numBlurPixelsPerSide = blur / 2.0;
// Incremental Gaussian Coefficent Calculation (See GPU Gems 3 pp. 877 - 889)
vec3 incrementalGaussian;
incrementalGaussian.x = 1.0 / (sqrt(2.0 * PI) * sigma);
incrementalGaussian.y = exp(-0.5 / (sigma * sigma));
incrementalGaussian.z = incrementalGaussian.y * incrementalGaussian.y;
vec4 avgValue = vec4(0.0, 0.0, 0.0, 0.0);
float coefficientSum = 0.0;
// Take the central sample first...
avgValue += texture2D(u_image, p) * incrementalGaussian.x;
coefficientSum += incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
// Go through the remaining 8 vertical samples (4 on each side of the center)
for (float i = 1.0; i <= numBlurPixelsPerSide; i += 1.0) {
avgValue += texture2D(u_image, p - i * texOffset) * incrementalGaussian.x;
avgValue += texture2D(u_image, p + i * texOffset) * incrementalGaussian.x;
coefficientSum += 2.0 * incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
}
gl_FragColor = avgValue / coefficientSum;
}
When I build, I get the following error message:
webgl-renderer.js?2eb3:137 Uncaught could not compile shader:ERROR:
0:38: 'i' : Loop index cannot be compared with non-constant expression
I have also tried to use just the uniform float blur to compare i to. Is there any way to fix this?
The problem is further detailed here: https://www.khronos.org/webgl/public-mailing-list/archives/1012/msg00063.php
The solution that I've found looking around is to only use a constant expression when comparing a loop var. This doesn't fit with what I need to do which is vary how many times I'm looping based on the blur radius.
Any thoughts on this?
This happens because on some hardware, GLSL loops are un-rolled into native GPU instructions. This means there needs to be a hard upper limit to the number of passes through the for loop, that governs how many copies of the loop's inner code will be generated. If you replace numBlurPixelsPerSide with a const float or even a #define directive, and the shader compiler can then determine the number of passes at compile time, and generate the code accordingly. But with a uniform there, the upper limit is not known at compile time.
There's an interesting wrinkle in this rule: You're allowed to break or call an early return out of a for loop, even though the max iterations must be discernible at compile time. For example, consider this tiny Mandelbrot shader. This is hardly the prettiest fractal on GLSL Sandbox, but I chose it for its small size:
precision mediump float;
uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;
varying vec2 surfacePosition;
const float max_its = 100.;
float mandelbrot(vec2 z){
vec2 c = z;
for(float i=0.;i<max_its;i++){ // for loop is here.
if(dot(z,z)>4.) return i; // conditional early return here.
z = vec2(z.x*z.x-z.y*z.y,2.*z.x*z.y)+c;
}
return max_its;
}
void main( void ) {
vec2 p = surfacePosition;
gl_FragColor = vec4(mandelbrot(p)/max_its);
}
In this example, max_its is a const so the compiler knows the upper limit and can un-roll this loop if it needs to. Inside the loop, a return statement offers a way to leave the loop early for pixels that are outside of the Mandelbrot set.
You still don't want to set the max iterations too high, as this can produce a lot of GPU instructions and possibly hurt performance.
Try something like this:
const float MAX_ITERATIONS = 100.0;
// Go through the remaining 8 vertical samples (4 on each side of the center)
for (float i = 1.0; i <= MAX_ITERATIONS; i += 1.0) {
if (i >= numBlurPixelsPerSide){break;}
avgValue += texture2D(u_image, p - i * texOffset) * incrementalGaussian.x;
avgValue += texture2D(u_image, p + i * texOffset) * incrementalGaussian.x;
coefficientSum += 2.0 * incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
}
Sometimes you can use my very simple solving of issue.
My fragment of the shader source code:
const int cloudPointsWidth = %s;
for ( int i = 0; i < cloudPointsWidth; i++ ) {
//TO DO something
}
You can see '%' : syntax error above. But I am replace %s to a number in my javascript code before use my shader. For example:
vertexCode = vertexCode.replace( '%s', 10 );
vertexCode is my shader source code.
Everytime if I want to change cloudPointsWidth, I am destroying my old shader and creating new shader with new cloudPointsWidth .
Hope sometimes my solving can to help you.
You can just do a for loop with large constant number and use a break.
for(int i = 0; i < 1000000; ++i)
{
// your code here
if(i >= n){
break;
}
}
I've had similar problem with image downsampling shader. The code is basically the same:
for (int dx = -2 * SCALE_FACTOR; dx < 2 * SCALE_FACTOR; dx += 2) {
for (int dy = -2 * SCALE_FACTOR; dy < 2 * SCALE_FACTOR; dy += 2) {
/* accumulate fragment's color */
}
}
What I've ended up doing is using preprocessor and creating separate shader programs for every SCALE_FACTOR used (luckily, only 4 was needed). To achieve that, a small helper function was implemented to add #define ... statements to shader code:
function insertDefines (shaderCode, defines) {
var defineString = '';
for (var define in defines) {
if (defines.hasOwnProperty(define)) {
defineString +=
'#define ' + define + ' ' + defines[define] + '\n';
}
}
var versionIdx = shaderCode.indexOf('#version');
if (versionIdx == -1) {
return defineString + shaderCode;
}
var nextLineIdx = shaderCode.indexOf('\n', versionIdx) + 1;
return shaderCode.slice(0, nextLineIdx) +
defineString +
shaderCode.slice(nextLineIdx);
}
The implementation is a bit tricky because if the code already has #version preprocessor statement in it, all other statements have to follow it.
Then I've added a check for SCALE_FACROR being defined:
#ifndef SCALE_FACTOR
# error SCALE_FACTOR is undefined
#endif
And in my javascript code I've done something like this:
var SCALE_FACTORS = [4, 8, 16, 32],
shaderCode, // the code of my shader
shaderPrograms = SCALE_FACTORS.map(function (factor) {
var codeWithDefines = insertDefines(shaderCode, { SCALE_FACTOR: factor });
/* compile shaders, link program, return */
});
I use opengl es3 on android and solve this problem by using extension above the beginning of program like this:
#extension GL_EXT_gpu_shader5 : require
I don't know whether it work on webGL, but you can try it.
Hope it can help.
You can also use template litterals to set the length of the loop
onBeforeCompile(shader) {
const array = [1,2,3,4,5];
shader.uniforms.myArray = { value: array };
let token = "#include <begin_vertex>";
const insert = `
uniform float myArray[${array.length}];
for ( int i = 0; i < ${array.length}; i++ ) {
float test = myArray[ i ];
}
`;
shader.vertexShader = shader.vertexShader.replace(token, token + insert);
}
I'm absolutely stumped as well as my instructors/lab-assistants.
For some reason, the following HLSL code is returning this in the output window:
error X8000 : D3D11 Internal Compiler error : Invalid Bytecode: Invalid operand type for operand #1 of opcode #86 (counts are 1-based).
Here's the function in the HLSL causing the issue:
// Projects a sphere diameter large in screen space to calculate desired tesselation factor
float SphereToScreenSpaceTessellation(float3 p0, float3 p1, float diameter)
{
float3 centerPoint = (p0 + p1) * 0.5f;
float4 point0 = mul( float4(centerPoint,1.0f) , gTileWorldView);
float4 point1 = point0;
point1.x += diameter;
float4 point0ClipSpace = mul(point0, gTileProj);
float4 point1ClipSpace = mul(point1, gTileProj);
point0ClipSpace /= point0ClipSpace.w;
point1ClipSpace /= point1ClipSpace.w;
point0ClipSpace.xy *= gScreenSize;
point1ClipSpace.xy *= gScreenSize;
float projSizeOfEdge = distance(point0ClipSpace, point1ClipSpace);
float result = projSizeOfEdge / gTessellatedTriWidth;
return clamp(result, 0, 64);
}
I've narrowed it down to the point where it may be the "mul" intrinsic. We've taken everything out of the code and tried to return out a temporary variable like this, and it works fine:
float SphereToScreenSpaceTessellation(float3 p0, float3 p1, float diameter)
{
float temp = 0;
float3 centerPoint = (p0 + p1) * 0.5f;
float4 point0 = mul( float4(centerPoint,1.0f) , gTileWorldView);
float4 point1 = point0;
point1.x += diameter;
float4 point0ClipSpace = mul(point0, gTileProj);
float4 point1ClipSpace = mul(point1, gTileProj);
point0ClipSpace /= point0ClipSpace.w;
point1ClipSpace /= point1ClipSpace.w;
point0ClipSpace.xy *= gScreenSize;
point1ClipSpace.xy *= gScreenSize;
float projSizeOfEdge = distance(point0ClipSpace, point1ClipSpace);
float result = projSizeOfEdge / gTessellatedTriWidth;
return temp;
//return clamp(result, 0, 64);
}
If anyone is wondering:
gTileWorldView, gTileProj are float4x4's in a .hlsli file
gScreenSize is a float2 in a .hlsli file.
gTessellatedTriWidth is a float in a .hlsli file.
The following function is as states in a 2011 NVidia shader at : http://dx11-xpr.googlecode.com/svn/trunk/XPR/Media/Effects/TerrainTessellation.fx
I tried to copy and paste their solution replacing their variables with the one above, and the same error listed happens.
I'm absolutely stumped and I need assistance in order to do this assignment, please help.
Check out this line:
point0ClipSpace.xy *= gScreenSize;
Is gScreenSize a float2? I do not believe you can scalar multiply a vec by any vec type.