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merge of blend_test and lerabot_blend_test, addition of 1 case, and...

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T_chan 2022-01-31 10:04:50 +00:00 committed by Luke Benstead
parent 9506237c47
commit ab627b5ef5
4 changed files with 40 additions and 143 deletions
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1
CMakeLists.txt
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@ -124,7 +124,6 @@ gen_sample(depth_funcs samples/depth_funcs/main.c)
gen_sample(depth_funcs_alpha_testing samples/depth_funcs_alpha_testing/main.c samples/depth_funcs_alpha_testing/gl_png.c)
gen_sample(depth_funcs_ortho samples/depth_funcs_ortho/main.c)
gen_sample(lerabot01 samples/lerabot01/main.c)
gen_sample(lerabot_blend_test samples/lerabot_blend_test/main.c)
gen_sample(lights samples/lights/main.c)
gen_sample(mipmap samples/mipmap/main.c)
gen_sample(multitexture_arrays samples/multitexture_arrays/main.c samples/multitexture_arrays/pvr-texture.c)

52
samples/blend_test/main.c
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@ -1,7 +1,8 @@
/*
* This sample is to demonstrate a bug where rendering an unblended
* polygon, before a series of blended ones would result in no blended
* output and incorrect depth testing
* This sample demonstrates blending, and the importance of drawing order,
* depth testing and z-value.
* This is a merge of lerabot_blend_test and blend_test, with 1 added case,
* and with adapted/corrected explanation
*/
#ifdef __DREAMCAST__
@ -82,13 +83,13 @@ void DrawGLScene()
const float NONE [] = {0, 0, 0, 0};
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
// LEFT UPPER SECTION
glLoadIdentity(); // Reset The View
glTranslatef(-4.0, 0, -10);
// LEFT SECTION
// This should draw 2 quad, a red first, then and overlapping blue one.
// This section draw both quad at the same Z value
glTranslatef(-4.0, 2.0, -10);
// This draws 2 quads, a red first, then an overlapping blue one.
// Both quads are drawn at the SAME z-value
// With depth test GL_LEQUAL, this means blending for the overlapping part
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
DrawQuad(RED);
@ -96,11 +97,24 @@ void DrawGLScene()
DrawQuad(BLUE);
glDisable(GL_BLEND);
// RIGHT UPPER SECTION
glTranslatef(4.0, 0, 0);
// This draws 2 quads, a red first, then an overlapping blue one.
// The blue quad has a LOWER z-value, so it is behind the red quad.
// With depth test GL_LEQUAL, the blue part is not considered for the overlapping part, so no blending
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
DrawQuad(RED);
glTranslatef(1.0, 0, -0.01);
DrawQuad(BLUE);
glDisable(GL_BLEND);
// RIGHT SECTION
// This should draw 2 quad, a red first, then and overlapping blue one.
// This section uses a HIGHER Z VALUE(0.01f), so the blue quad should be in FRONT of the red quad.
// LEFT DOWN SECTION
glLoadIdentity(); // Reset The View
glTranslatef(-4.0, -1.0, -10);
// This draws 2 quads, a red first, then an overlapping blue one.
// The blue quad has a HIGHER z-value, so it is in front the red quad.
// With depth test GL_LEQUAL, this means blending for the overlapping part
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
DrawQuad(RED);
@ -108,6 +122,20 @@ void DrawGLScene()
DrawQuad(BLUE);
glDisable(GL_BLEND);
// RIGHT DOWN SECTION
glTranslatef(4.0, 0.0, -0.01);
// This is basically the same as the RIGHT UPPER SECTION, except that the blue quad
// is drawn first.
// With depth test GL_LEQUAL, this means blending for the overlapping part
// <- the order of drawing is important for blending !
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glTranslatef(1.0, 0.0, -0.01);
DrawQuad(BLUE);
glTranslatef(-1.0, 0.0, 0.01);
DrawQuad(RED);
glDisable(GL_BLEND);
glKosSwapBuffers();
}

130
samples/lerabot_blend_test/main.c
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@ -1,130 +0,0 @@
/*
* This sample is to demonstrate a bug where rendering an unblended
* polygon, before a series of blended ones would result in no blended
* output and incorrect depth testing
*/
#ifdef __DREAMCAST__
#include <kos.h>
#endif
#include "GL/gl.h"
#include "GL/glu.h"
#include "GL/glkos.h"
/* A general OpenGL initialization function. Sets all of the initial parameters. */
void InitGL(int Width, int Height) // We call this right after our OpenGL window is created.
{
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // This Will Clear The Background Color To Black
glClearDepth(1.0); // Enables Clearing Of The Depth Buffer
glDepthFunc(GL_LEQUAL); // The Type Of Depth Test To Do
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glEnable(GL_TEXTURE_2D);
glShadeModel(GL_SMOOTH); // Enables Smooth Color Shading
glDisable(GL_BLEND);
glMatrixMode(GL_PROJECTION);
glLoadIdentity(); // Reset The Projection Matrix
gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f); // Calculate The Aspect Ratio Of The Window
glMatrixMode(GL_MODELVIEW);
}
/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
void ReSizeGLScene(int Width, int Height)
{
if (Height == 0) // Prevent A Divide By Zero If The Window Is Too Small
Height = 1;
glViewport(0, 0, Width, Height); // Reset The Current Viewport And Perspective Transformation
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
glMatrixMode(GL_MODELVIEW);
}
int check_start() {
#ifdef __DREAMCAST__
maple_device_t *cont;
cont_state_t *state;
cont = maple_enum_type(0, MAPLE_FUNC_CONTROLLER);
if(cont) {
state = (cont_state_t *)maple_dev_status(cont);
if(state)
return state->buttons & CONT_START;
}
#endif
return 0;
}
void DrawQuad(const float* colour) {
glBegin(GL_QUADS);
glColor4fv(colour);
glVertex3f(-1.0,-1.0, 0.0);
glVertex3f( 1.0,-1.0, 0.0);
glVertex3f( 1.0, 1.0, 0.0);
glVertex3f(-1.0, 1.0, 0.0);
glEnd();
}
/* The main drawing function. */
void DrawGLScene()
{
const float RED [] = {1.0, 0, 0, 0.5};
const float BLUE [] = {0.0, 0, 1, 0.5};
const float NONE [] = {0, 0, 0, 0};
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity(); // Reset The View
glTranslatef(-4.0, 0, -10);
// LEFT SECTION
// This should draw 2 quad, a red first, then and overlapping blue one.
// This section draw both quad at the same Z value
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
DrawQuad(RED);
glTranslatef(1.0, 0, 0);
DrawQuad(BLUE);
glDisable(GL_BLEND);
glTranslatef(4.0, 0, 0);
// RIGHT SECTION
// This should draw 2 quad, a red first, then and overlapping blue one.
// This section uses a LOWER Z VALUE(-0.01f), so the blue quad should be in FRONT of the red quad.
// lerabot's note : changing the z value to positive gives the desired output.
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
DrawQuad(RED);
glTranslatef(1.0, 0, -0.01);
DrawQuad(BLUE);
glDisable(GL_BLEND);
glKosSwapBuffers();
}
int main(int argc, char **argv)
{
glKosInit();
InitGL(640, 480);
ReSizeGLScene(640, 480);
while(1) {
if(check_start())
break;
DrawGLScene();
}
return 0;
}

0
samples/lerabot_blend_test/romdisk/PLACEHOLDER
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