Trying to draw particle

[k-off]

I'm trying to draw something similar to the vanilla sweeping attack particle, except where that's a 128x16 texture with 8 frames, I have a 96x16 with only 2 frames. I'm looking through the vanilla code and trying to decipher how they've drawn the vertices, but I'm confused on a couple things:

 

        int i = (int)(((float)this.life + partialTicks) * 3.0F / (float)this.lifeTime);

        if (i <= 7)
        {
            this.textureManager.bindTexture(SWEEP_TEXTURE);
            float f = (float)(i % 4) / 4.0F;
            float f1 = f + 0.24975F;
            float f2 = (float)(i / 2) / 2.0F;
            float f3 = f2 + 0.4995F;
            float f4 = 1.0F * this.size;
            float f5 = (float)(this.prevPosX + (this.posX - this.prevPosX) * (double)partialTicks - interpPosX);
            float f6 = (float)(this.prevPosY + (this.posY - this.prevPosY) * (double)partialTicks - interpPosY);
            float f7 = (float)(this.prevPosZ + (this.posZ - this.prevPosZ) * (double)partialTicks - interpPosZ);
            GlStateManager.color(1.0F, 1.0F, 1.0F, 1.0F);
            GlStateManager.disableLighting();
            RenderHelper.disableStandardItemLighting();
            buffer.begin(7, VERTEX_FORMAT);
            buffer.pos((double)(f5 - rotationX * f4 - rotationXY * f4), (double)(f6 - rotationZ * f4 * 0.5F), (double)(f7 - rotationYZ * f4 - rotationXZ * f4)).tex((double)f1, (double)f3).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
            buffer.pos((double)(f5 - rotationX * f4 + rotationXY * f4), (double)(f6 + rotationZ * f4 * 0.5F), (double)(f7 - rotationYZ * f4 + rotationXZ * f4)).tex((double)f1, (double)f2).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
            buffer.pos((double)(f5 + rotationX * f4 + rotationXY * f4), (double)(f6 + rotationZ * f4 * 0.5F), (double)(f7 + rotationYZ * f4 + rotationXZ * f4)).tex((double)f, (double)f2).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
            buffer.pos((double)(f5 + rotationX * f4 - rotationXY * f4), (double)(f6 - rotationZ * f4 * 0.5F), (double)(f7 + rotationYZ * f4 - rotationXZ * f4)).tex((double)f, (double)f3).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
            Tessellator.getInstance().draw();
            GlStateManager.enableLighting();
        }

 

1. What is the purpose of adding what seems like arbitrary values f1 and f2 if they're already in the correct positions relative to the texture? Unless it's not 0->0.25 but instead 0.25->0?

 

2. The image is 128 pixels wide with 4 frames across the columns, meaning each frame is 32 pixels wide and 16 pixels tall. How does this know to draw a quad with the correct size for a frame? Everything appears to be in terms of the texture ratios.

Edited May 29, 2020 by k-off

[k-off]

So now the particle's various ticking methods are being called, but the particle is not being rendered. I can also confirm that the texture's frame is correctly calculated as well.

 

        mc.getTextureManager().bindTexture(SLASH_TEXTURE);

        float f = (float)(currentAnimationFrame / 2.0);

        float f1 = f + 0.4995F;
        float f2 = 0.0F;
        float f3 = f2;
        float f4 = 1.0F;
        float f5 = (float)(this.prevPosX + (this.posX - this.prevPosX) * (double)partialTicks - interpPosX);
        float f6 = (float)(this.prevPosY + (this.posY - this.prevPosY) * (double)partialTicks - interpPosY);
        float f7 = (float)(this.prevPosZ + (this.posZ - this.prevPosZ) * (double)partialTicks - interpPosZ);
        GlStateManager.pushMatrix();
        GlStateManager.enableBlend();
        GlStateManager.blendFunc(GlStateManager.SourceFactor.SRC_ALPHA, GlStateManager.DestFactor.ONE_MINUS_SRC_ALPHA);
        GlStateManager.alphaFunc(516, 0.003921569F);
        GlStateManager.color(1.0F, 1.0F, 1.0F, 1.0F);

        bufferIn.begin(7, VERTEX_FORMAT);
        bufferIn.pos((double)(f5 - rotationX * f4 - rotationXY * f4), (double)(f6 - rotationZ * f4 * 0.5F), (double)(f7 - rotationYZ * f4 - rotationXZ * f4)).tex((double)f1, (double)f3).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
        bufferIn.pos((double)(f5 - rotationX * f4 + rotationXY * f4), (double)(f6 + rotationZ * f4 * 0.5F), (double)(f7 - rotationYZ * f4 + rotationXZ * f4)).tex((double)f1, (double)f2).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
        bufferIn.pos((double)(f5 + rotationX * f4 + rotationXY * f4), (double)(f6 + rotationZ * f4 * 0.5F), (double)(f7 + rotationYZ * f4 + rotationXZ * f4)).tex((double)f, (double)f2).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
        bufferIn.pos((double)(f5 + rotationX * f4 - rotationXY * f4), (double)(f6 - rotationZ * f4 * 0.5F), (double)(f7 + rotationYZ * f4 - rotationXZ * f4)).tex((double)f, (double)f3).color(this.particleRed, this.particleGreen, this.particleBlue, 1.0F).lightmap(0, 240).normal(0.0F, 1.0F, 0.0F).endVertex();
        Tessellator.getInstance().draw();
        GlStateManager.popMatrix();

 

It's supposed to spawn at the player's position. 

[TheGreyGhost]

Howdy

Looks like old rendering code!!  I suggest updating to 1.15.2, it's much better.

https://gist.github.com/williewillus/30d7e3f775fe93c503bddf054ef3f93e

 

The example custom particle generation in here might be useful

https://github.com/TheGreyGhost/MinecraftByExample/tree/master/src/main/java/minecraftbyexample/mbe50_particle

 

Some suggestions

1) Refactor that code to have meaningful names - it's almost impossible to understand otherwise.

2) f, f1, f2, f3 are the u,v, coordinates corresponding to the opposite corners of the quad being rendered.

Quote

2. The image is 128 pixels wide with 4 frames across the columns, meaning each frame is 32 pixels wide and 16 pixels tall. How does this know to draw a quad with the correct size for a frame? Everything appears to be in terms of the texture ratios.

The quad is always drawn the same size regardless of the texture size.  If you make the texture bigger, the detail in the quad gets better (the texels are drawn smaller) but the quad does not get larger.

Quote

It's supposed to spawn at the player's position. 

There are lots of possible reasons, eg the texture is wrong, you're drawing to the wrong buffer, you're drawing in completely the wrong place, your render code is not being called.

Some general tips I've found useful:

1. Take baby steps.  Start with drawing a simple quad.
2. Move to near [0,0,0] in the world.  Sometimes you will see your quad being rendered close to the origin

-TGG